PCEngine-FX.com

Hello Everyone,

I will have the differences between the PCE/Turbo/Duo-R listed in the next few weeks; one of each is in for repair right now. If people would like to chime in with tips, corrections, or additions, please do so and I will update the guide. A section on adjusting the posts will be towards the end as soon as I have gathered all the information.  For each successful repair you will need:

1 HOP-M3 Laser
1 Duo (Turbo Duo, PCE Duo, Duo-R, Duo-RX)
1 Torx T-10 bit/screwdriver with a security center (Japanese Systems)
  OR
1 5/16" Gamebit (USA Turbo Duo)
1 Small bottle of White Lithium or Clear Silicone Grease
5 #40 x 1/2" Phillips head pan screws to replace the T-10's (optional)

PC Engine Duo (Black):

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4790&image)
pce-duoswap001.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap001.jpg)}

There are two generations of the PCE Duo, this being the first gen with the "Large Capacitor" as chop5 has pointed out.  First, flip the duo over and pull out each of the five Torx T-10 screws. A T-10 Security Torx Bit with recessed center point can be purchased at Sears or a Hardware store. A regular flat t-10 can be used but it's harder to navigate around the center security bit and you risk rounding out the screw.
sears.com/t10-security-tee-insert-bit-tools (https://www.sears.com/eazypower-13242-t10-security-tee-insert-bit-tools/p-SPM7728672403)
power-tool-accessories/drill-bits/2629392 (https://www.acehardware.com/departments/tools/power-tool-accessories/drill-bits/2629392)
product_image/27SBT10.jpg (https://web.archive.org/web/20150315101514im_/http://www.metrofixings.co.uk/images/product_image/27SBT10.jpg)
_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4792&image)
pce-duoswap002.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap002.jpg)}

Once you remove them, put them in a small cup or shot-glass to make sure you have easy access to them I recommend replacing them with a comparable Phillips head (take one of the screws to your local Ace or True Value Hardware Store and get five #40 x 1/2" pan screws) so you don't have to deal with the headache again.

Now that the system is open, carefully lift the cover directly off of the board and bottom casing. Take your time so you don't harm any of the internals.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926.0&attach=4794&image)
pce-duoswap003.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap003.jpg)}

NOTE: The unit pictured has had a complete cap replacement with green hi-temp NTK capacitors, so if yours are small and silver, don't panic, this is the normal OEM setup. Now, Zooming In on the Laser area...

The motor for the laser (silver cylinder, top of photo 4) is a typical 9V motor that can be found at a hobby store and can be tested for continuity with a 9v battery due to the PCE Duo's 9V voltage. It's hard to get the dang thing back in, de-soldering the wire is the easy part, just watch those gears. The very tiny screws are aluminum, and non-magnetic so make sure you have a steady hand if you have to replace the motor. I've only seen one go bad, ever so I would bet this is not the issue. Make sure to add some extra White Lithium Grease at this point to ensure your gears stay properly lubricated.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926.0&attach=4796&image)
pce-duoswap004.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap004.jpg)}

Carefully, and not forcing it, lift the laser cover off from the bottom right-hand corner of the cover, it should click right off, and pull away to the left; always make sure not to disturb the laser or the wires.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4798&image)
pce-duoswap005.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap005.jpg)}

Now that we have the laser cover off, we can see what the laser really looks like and what it is connected to. The laser slides across two metal posts that hold it on its track, and it connects to the motor and two gears via the top track which is part of the laser assembly. The HOP-M3 is connected to the motherboard by two ribbon cables; the white connector on the top, and the red connector on the bottom.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4800&image)
pce-duoswap006.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap006.jpg)}

Presumably your laser has been returned to the origin position, next to the spindle, like in the next photo. DO NOT UNDER ANY CIRCUMSTANCES, FORCE THE LASER at this point, for risk of harming the fragile plastic gears. Next, very gently; unplug the two connectors (the white first, then the red) applying equal pressure on both sides of the connectors, so you don't harm them or pull a wire off or out of the plug(s).

At this point we must Zoom in again to the right-hand side of the laser assembly, specifically the two black plastic 90 degree screws that hold the tracks in place (note: the tracks are not held in on the left side, so be careful when removing them so you don't pull wire or move too quickly).   

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926.0&attach=4802&image)
pce-duoswap007.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap007.jpg)}

At this point the black screws need to "opened" so the laser can be lifted up and slid off the tracks. Using a Phillips head screwdriver, turn each of the screws 90 degrees CCW.

Now, carefully; lift the tracks from the right side at a very gradual angle (almost vertical at first) to first unseat the track from the gears, and then lift the tracks up and to the left to  slide off the old laser. Remember that on the left side the tracks are in a seat, and not connected to anything.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4804&image)
pce-duoswap008.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap008.jpg)}

The New HOP-M3 arrived from Electronix.com, in a sealed blue plastic bag. The price was around $22 plus shipping. The customer service reps were very friendly, and they give volume discounts with the more you buy. Here is a direct link to the laser, don't let the stock photo fool you. If you don't get the correct one they will make your order right.

archive.org/cd-dvd-cd-pickups-c-435_440_450_456 (https://web.archive.org/web/20110127162756if_/http://www.electronix.com/cd-dvd-cd-pickups-c-435_440_450_456.html)
electronix.com/cd-pickup-hopm3-p-14472.html - No longer in business/stock, try eBay!
Model: HOP-M3, Cost: $18.95
(https://web.archive.org/web/20110718230957im_/http://www.electronix.com/images/cdstock.jpg)

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4806&image)
pce-duoswap009.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap009.jpg)}

Make sure to use plenty of white lithium grease on the tracks after the re-installation of the new laser, and make sure to lay it down vertically initially as to not harm the gears again. Lube the gears with plenty of grease, and also the arm for the motor, which may be close to dry as well.

Once the new laser is back in place secure the tracks by putting them flat, and turning the black plastic lock-screws 90 degrees clockwise. Now that the HOP-M3 is physically installed, clip back in the two wire connectors; red first, white second, applying even pressure on both side while taking care to not to force it, or harm the laser. You should feel a "click" upon successful re-installation of the clips. Make sure they're on there tight.

At this point, your Duo should look like Image #6. Re-install the dust cover for the CD; without it it is very common to get a "Set Disc Error". Angle it downward towards the left top corner, and install that corner first, then apply even pressure while clicking down on the bottom right side. The dust cover should set nicely back into place.

Your Laser is now physically installed.

_{(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=4808&image)
pce-duoswap0010.jpg (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/pce-duoswap0010.jpg)}

Provided your Duo does not need a Pot adjustment, You can close it back up. Remember to replace the security bits with the Phillips head screws.

Adjusting the Pots:

Advanced Users/Modders only! (unless you really want to risk it...)

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

Tips: The main issue is breaking a pot, or putting it so out of whack the CD player won't read discs at all. Be very gentle, and go SLOWLY when rotating the screwdriver, trying for just a few degrees (out of 360) at a time. This is 20 year-old technology and electrolytic fluid may have weakened the traces. VR102 is the place to start. Please reference BMW's photo below before proceeding.

What You will need:
1 Multimeter with Resistance (Ohms)
1 #0 Philips-head Screwdriver
1 Ocilloscope (optional)

Regarding the Trim Pots For the Turbo Duo/PCE Duo and taken from this post:

pcengine-fx.com/forums/index.php?topic=3586.0 (https://www.pcengine-fx.com/forums/index.php?topic=3586.0)

Quote from: Charlie on 06/29/2009, 06:00 PMThese measurement points may help.

VR101 = E/F balance, pin 13 of U101
VR102 = Focus Offset, pin 18 of U101
VR103 = Track Gain (Track error level), pin 45 of U102
VR104 = Focus Gain, pin 48 of U102
VR105 = VCO, pin 30 of U102

Charlie

Also, the Duo-R and DuoRX DO NOT have a vr104 pot.

Quote from: dudule on 11/21/2009, 06:21 AMmy DuoRX:

vr101:AB=12.33 AC=10.65 BC=19.55
vr102:AB=7.89 AC=8.11 BC=11.28
vr103:AB=7.25 AC=7.14 BC=18.46
vr105:AB=0.38 AC=0.00 BC=0.38

Thanks to BlueBMW for this troubleshooting/repair link and adjustment photo that is very helpful!!!:

http://www.repairfaq.org/sam/cdfaq.htm (http://www.repairfaq.org/sam/cdfaq.htm)

(https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=5739&image) (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/Duo%20Laser%20Swap%20Guide/tduopots.jpg)

Also BlueBMW's guide to adjusting the pots by ear, which is brilliant!

Quote from: BlueBMW on 11/20/2010, 10:27 PMAddendum:  Adjusting the pots by ear!

Adjusting your duo's pot can be a daunting task for anyone.  With the high cost of replacement hardware, none of use want to permanently damage our precious Duos!  Here I will try and explain in idiots terms, the adjustment of the Duo pots.

Preliminary setup:

I do my adjustments live.  Meaning I have the system on and hopefully spinning / reading the disc while I do adjustments.  To facilitate this, I remove the magnet from the CD lid (turn the retainer ring until it releases the magnet)  And then I place a piece of tape or whatever over the lid closed switch.  At this point I place an audio CD on the spindle and place the magnet on top of it to hold it in place.

Adjustment:

I use a small philips screwdriver to turn the pots.  If you look closely at them, they have 4 little notches that a screwdriver fits into perfectly.

Once you have a CD in place and everything is ready to go, turn on the system.  If you don't want to connect your Duo to a tv, you can use headphones instead.  Press the run button on the controller.  If the CD starts spinning.... Great!  If not, we'll start with two of the pots:

VR102 and VR104

VR102 has a small range of adjustment in which the CD will start to spin.  If you turn it and the cd starts to spin, then you know you have found one end of the adjustment.  Keep turning it until the CD stops again.  Once you know approximately where those two points are, you can find a sweet spot in the middle.

VR104 seems to be similar to VR102 in that there is a certain range in which the CD will spin.  Again try and find the sweet spot in the middle of the two points of spin/no spin.

By this point, hopefully you have the CD spinning, and maybe even attempting to read!  So lets move on to the next pot/s.....

VR101 and VR103

VR101 is kind of a by ear pot.  There seems to be a small range that works for proper cd playback.  Typically it seems to be in the 0 to 45 degree range with 0 degrees being horizontal.  You should hear some scratchy funny noises when VR101 isn't adjusted properly.  Try and find a quiet spot for it.  If you go too far it will get very noisy.  Hopefully you can find a spot where the CD audio will start to play.

VR103 is, from what I can tell, an error correction adjustment.  Hopefully you have got a CD spinning reliably at this point.  You might hear a whiney faint scratchy noise at this point.... adjust VR103 clockwise until the noise goes away.  If you go too far, the noise will come back only it will be a lower tone and not sound good. :P  Try and find the sweet spot where the laser operates quietly.

VR105

Lastly, VR105....  This is an adjustment for the spindle speed correction.  I'm not 100% on the best way to describe adjusting this one.  Basically if the spindle speed starts to run away (go REALLY fast) then you've gone too far.  Hopefully by this point, your CD will play music.  Try and play later tracks on the CD and if they struggle to play, try adjusting VR105 until you can play all the tracks reliably.

Hopefully this helps, any suggestions are appreciated!

legendary thread! thanks bleu
CAW!

Nice work! Please sticky this thread!

Excellent guide bluebird!   :dance:

So what is the risk by adjusting the pots? And some oscilloscope or ohmmeter tips?

Again this is epic!

Quote from: Opethian on 11/20/2010, 08:28 PMlegendary thread! thanks bleu
CAW!

Quote from: Duo_R on 11/20/2010, 09:46 PMNice work! Please sticky this thread!

Quote from: BlueBMW on 11/20/2010, 10:27 PMExcellent guide bluebird!   :dance:

Thanks Guys, I really appreciate the tips and pointers and I couldn't have done it without the help! It would be awesome if this became a sticky topic. CAW :D

Quote from: Duo_R on 11/21/2010, 12:48 AMSo what is the risk by adjusting the pots? And some oscilloscope or ohmmeter tips?

I just updated the guide with the tools for the adjustments. Just be incredibly careful and make sure the positive/negative tips are clean so you get an accurate reading. I added a few "tips" at the beginning of the thread too, and when I get some oscilloscope readings I will post visual shots.

Quote from: Duo_R on 11/21/2010, 12:48 AMAgain this is epic!

Thank You again, Duo_R!

Just wanted to display a pinout of the pots to make sure we are measuring them the same:

(?action=dlattach&topic=8926&attach=5819&image)

Now I did some readings on my two Duos. My U.S. Duo back in the day had problems and I sent over to Retrogames to have the laser fixed. The guy also said he "calibrated" my laser to better ready CDR's. Compared to all the other Duo systems I have, this one reads anything I throw at it. Compared to my Duo-R and PCE Duo, the CDR capability is superior. Here are the results of reading the pots. NOTE - I tested the laser pot, and both readouts were the same.

(?action=dlattach&topic=8926&attach=5821&image)

So looking at my stats, the only real difference from my PCE Duo and US Duo (that was repaired by Retrogames) is VR105. Everything else is pretty close, and the laser pots read the same. Is VR105 the secret to improving CDR calibrate ? Based on this information it doesn't make it seam that way.  :-k

And yes, I am getting a reading of 300 (no decimal) on VR105 for AC and BC measurements.

QuoteLastly, VR105....  This is an adjustment for the spindle speed correction.  I'm not 100% on the best way to describe adjusting this one.  Basically if the spindle speed starts to run away (go REALLY fast) then you've gone too far.  Hopefully by this point, your CD will play music.  Try and play later tracks on the CD and if they struggle to play, try adjusting VR105 until you can play all the tracks reliably.

Caution - I am not saying to calibrate your Duo to 300 for VR105, only trying to figure out what the Retrogames guy did to read CDR's so damn well. :wink:

Update: OK did another read on VR105:

VR105:
AB: 0
AC:  .300
BC: .300

I am going to blame it on the cheepie ohmeter, looks like it wasn't displaying the decimal there. Not sure about the AB measurement but this is what I am getting now. Ok going to throw away the cheepie ohmeter now. :lol:

Ill ohm out my pots today and see what mine are at.

VR105 is a 3k (ie: 3000) ohms rheostat, not a potentiometer; it sets the servo VCO.  The spindle speed takes off because you have gone out-of-lock.

Looks like you are measuring the full value, but with the decimal point wrong.  It seems strange that you would get this value, I would expect something smaller...unless the value you are measuring ACTUALLY IS 300 ohms.

Charlie

It took one long night, but I was successfully able to replace the laser on my duo!  :dance:
It was a long tedious process, but I took the upmost extreme caution to remove those two connectors. It is kind of funny, at first I thought I had to remove the entire white square that was attached to green board of the laser. I later found out that the connector was only part of the white square, as the rest of it is attached to the laser.  :lol:

Once I got that issue straightened out, I saw that I had very little room to work with to grab hold of the white connector as it were so close to those fragile wires. The only tool I had to grab hold of that connector were flat pliers. What I did was that I took one of those small precision screwdrivers, and I started nudging the sides of the white connector forward, alternating on each side, until I had enough room to grip with the pliers. Then I started using the pliers to wiggle the connector back and forth, which took a lot longer than I expected it to. Those suckers are plugged in real tight, but I didn't get too aggresive. After I got the white connector off, the red one was next.

Unfortunately, the red connector was too far low for me to nudge the sides with the screwdriver.  So what I did was remove the laser from the system, with the red connector still attached, and then I flipped the laser over so that I could see the bottom of the red connector. I then took a sewing needle and started pushing the red connector forward from the bottom through each of the ~six gaps. I did not even have to use pliers to remove this one!

The only hiccup I had, was that one of the two bars that hold the laser in place became unglued. But the system seems to work fine as the bar seems  securely fastened with the screw in place.

Before I start partying like it's 1999, I will test out the system extensively after thanksgiving. But when I did a test run of about 15 minutes, everything seemed great.

This is the first tekkie repair i've ever done, so it's a real confidence booster. But I won't be soldering anything anytime soon. One small step for Chan, one giant step for my Turbo Duo. :)

Thanks to everyone on here that contributed to this awesome laser guide. And also for those who had the patience to answer all of my questions in the shoutbox. You guys are awesome. 

Quote from: Charlie on 11/25/2010, 10:20 AMVR105 is a 3k (ie: 3000) ohms rheostat, not a potentiometer; it sets the servo VCO.  The spindle speed takes off because you have gone out-of-lock.

Looks like you are measuring the full value, but with the decimal point wrong.  It seems strange that you would get this value, I would expect something smaller...unless the value you are measuring ACTUALLY IS 300 ohms.

Charlie

Thank You very much Charlie, this trim pot has been a point of question for me for the last few months, specifically what its exact function was... Your expertise and input is invaluable!

Quote from: Duo_R on 11/25/2010, 04:30 AMUpdate: ok did another read on VR105:

VR105:
AB: 0
AC:  .300
BC: .300

I am going to blame it on the cheepie ohmeter, looks like it wasn't displaying the decimal there. Not sure about the AB measurement but this is what I am getting now. Ok going to throw away the cheepie ohmeter now. lol

Thanks you for the updates, Duo_R and BMW, I appreciate the follow-up!

Quote from: chany60126 on 11/25/2010, 11:50 AMIt took one long night, but I was successfully able to replace the laser on my duo!  :dance:

chany, I'm glad it went well! Congratulations!

I'm glad the connectors didn't give you any heck, sometimes they can be fragile, I overstated this a bit to stress the fragility of the wires. good call on the needle.

Already a satisfied customer :mrgreen: Enjoy Your Duo!

Excellent thread. I made some crude pictures about taking off the connectors from the laser if they are any help to anyone:

(https://img.photobucket.com/albums/v238/jetbue7/duolasercordpic2.jpg) (https://img.photobucket.com/albums/v238/jetbue7/crudedrawingoflaser.jpg)

Another invaluable resource to the NEC community! Great job  =D>

question, where can i get the grease?
can i get it off electronix so i can save on shipping?

Any electronic store, Radio Shack, or major-chain store that has an electronics section.

Quote from: bartre on 02/01/2011, 07:47 PMcan i get it off electronix so i can save on shipping?

I've only bought lasers from them.

I've been at the pot adjustment for a while, but just can't get the disc to load properly. after adjusting each one i can get the disc to spin, appear to try to read, spin faster then the led goes out and "please set disc" if vr102 and vr104 effect getting the disc to physically spin, then i assume my issues are more with vr101, 103, and 105. but after an hour and a half of adjustments, still no progress. most of the time the acces light goes out and starts back up, like its resetting and trying to read over and over...

incrediblehark, I have a Duo right now that exibits the same issue :-k  Is this the unit you're doing the capacitor swap on?

yeah it is, i finished all of the caps (except for the two I mentioned to you through pm) and even got a second replacement hop-m3 that i made sure not to fiddle with this time. I can tweak the pots to get the cdrom spinning and pretty quiet, except for a few squeals when its attempting to read the disc, but no go. any time i feel like im making progress the access light goes out like the power gets cut off or something.

Quote from: incrediblehark on 03/04/2011, 09:29 PMyeah it is, i finished all of the caps (except for the two I mentioned to you through pm) and even got a second replacement hop-m3 that i made sure not to fiddle with this time. I can tweak the pots to get the cdrom spinning and pretty quiet, except for a few squeals when its attempting to read the disc, but no go. any time i feel like im making progress the access light goes out like the power gets cut off or something.

I'll be investigating this issue some more.  I'll get back to you once I figure out what's wrong with my unit.

when i was adjusting mine i had the same issues.
all the pots had to be close to get any CDR to read/load
i used an original/stamped cd and was able to get it to load with the pots near center.
i than slowly adjusted with a CDR till i had solid reads

I agree...this sounds like the normal "can't quite get the pots set right" problem.  This has happened to every CD drive I have repaired.  You need to move the pots in small increments (then wait a second or two) until you get the desired results, then keep going until it dies, then go back to the middle sweet spot.  

Of course, if you have a VOM, it's quite a bit easier.  I'm sure the voltages are on some thread here somewhere.

Charlie

I have had two units in the past that exhibited random sounds skips and or stopping. Turned out there was something up with the rails that the lens moved on. I switched the two rails around and it started working just fine. So I assume the lens was hanging up somehow on them.

i have seen the same thing and cleaning the rails and gears, than regreasing solved

hi every one can some one help me i have been working on a japan pc engine duo for 3 months with the vr pots to try and get it to load discs
and  :cry: still nothing the new laser i have tryed on a other mates unit and works so i know the laser is ok tested
if someone would help me that would be cool.
i would even be willing to send it to someone.
i am in the uk but willing to pay to fix this unit.

Have you replaced all the capacitors on this unit?  I have had several Duos that would not read cds despite pot adjustments.  After a cap swap, thy read cds just fine.

if its a -R or -RX, try resoldering the pots, as these are not surface mount and coupled with a poor quality board verry likely have damaged solder joints, or runs on them

I just bought a new HOP-M3 laser.  No problem getting it installed.  All my problem games with audio cut out or loading issues are completely fixed.  Every game I threw at it that had issues with my old laser is gone!  :dance:  However, I now have a fairly audible high pitched "WEEEEEEEEEEEEEEEEEEEEEEEE" sound.  So I'm guessing I need to adjust the pots?  I really don't want to mess with them since I am not having any read issues.  Is there a certain pot that might silence the sound.  I would like to know which pot to go for first.  Any info would be greatly appreciated.

Use a fine tip sharpie and make line across the case and adjustment knob, then you can set right back to all your sweet spots.

So you're talking about the pot on the lens itself.  What about the others mentioned like VR101-105 on the board?

dont adjust the pot on the new laser, as you could kill the laser.
its the ones on the system you want to adjust

Thanks for the reply Steve.  For the high pitched weeeee sound which pots to do recommend?

if i recall right it was one on the left, closest to the drive

Did the adjustment live and did about a 1/8 turn.  Took care of the sound right away.  Everything is reading fine.  Thanks again.

Has anyone here ever seen a duo lens vibrate and buzz? I recently had this issue on a Pcengine duo. The lens would work well for about 15-20 minutes and then just start vibrating uncontrollably right to left. Even made buzzing noises when the system was just turned on without even using the CD drive. I have fixed the problem with a new lens but man that old one freaked me out.

it had a broken wire on the focus or tracking coils keith

Thanks for the reply steve. However the same thing happened with my new lens after about 30 minutes as well so I kept at it and found the problem. It was one of the surface mount capacitors on the under side of the motherboard. Weird huh. I've never had one of those go bad on me before.

that is odd keith as those rarely fail
how did you find it?

strangely enough there was some black looking goo on the top of it so I figured I'd change it out. Also, there was a whole mess of red looking crud almost like rust underneathe it that I brushed off. Maybe that was the cuplrit and not the actual capacitor.

was it a tant or ceramic?
a tant cap is my guess, as thats how they fail.
rarely does a tant or ceramic cap fail (without abuse)
ceramics tend to short suddenly
tant tend to slowly short, often recovering when power removed (causing lots of heat)

thx very much for all info. and guide here, this thread is Gold!
cheer
darren

thx very much for all info. and guide here, this thread is Gold!
cheer
darren

Thanks for this guide! I'm trying a calibration but I'm a bit lost in the middle of the process... Here's the story/ My recaped duo had some difficulties reading original CDs, loading time were getting longer and longer...well my lens was dying.So i bought a new HOP-M3 and installed it crossing my fingers that it would work straight away. Well, it didn't, CD spins faster and faster then stop with the infamous "please set disc". I red the tutorial and as Cd was spinning , i by passed VR104 and VR102 adjustment. So then i aimed VR 101 with no result... all i got is this vinyl scratch alike sound or no sound at all but disc spinning faster and faster until i get the please set disc. When turning CR 101, i'm able to modulate time before the psd of death , laser seems to read with those scratchy noises but no luck...
Maybe i'm doing something wrong but i don't have a clue so here are my questions:
can we adjust the pot "live" meaning can we turn the pot(change the value)  while the disc is spinning or do we have to try a value, try to load disc, stop, change value, try to load, etc...?
Do i have to check for VR 103 now or should my CD (original audio) start to play only by adjusting VR 101?
As i got an oscilloscope at home, is there a tutorial on how adjust pots using oscilloscope?

Thanks again for this thread,

  Mike

cd spinning faster means buffer empty.
start sequence is (start position)(focus hunt)(mirror detect)(focus good)(spin)(TOC read)(buffer)
your losing it at buffer or TOC
the new laser may be defective (i have seen this)
your new laser may be too bright (i have seen this too)turn pot on lens CCW 1/8 to 1/4 turn and try again
yes adjust live.
I havent seen a tutorial using a scope, but i should do one based on pioneer instructions, as i have them handy.

http://www.repairfaq.org/sam/cdfaq.htm

Thanks for your help! I'll check pot value on both old and new lens and adjust the new one a bit lower as you suggest to see if it helps. Can you confirm it should start reading only by messing with VR 101 ? I don't have to touch VR 103 for now?

Mike

Update: got my music CD start playing but after a few seconds,  sound get crunchy and it stops :(  Any hints?

hi mike
 the pots adjusting is really time consuming.....I have apent 100+ hours , to feel the actual situation, steve is really helpful. I have fixed one of my duo-r perfectly, Im still working on my s-video moded duo-r, I have gone through stages like you, from nothing , start read  a bit, then end up spin all cd's, make sure it read the last track of cd, or your console wont read game correctly,I think vr 102,vr 105 are the pots you need to focus at
hope this help,
cheers
darren ( die hard pce fans for 25 years)

Yeah,it is a really long lasting work! I'm gonna try an other "hardcore" session and if it doesn't work, i'll try to do it with my oscilloscope if i happen to find necessary point points on the motherboard. I really want to play my forgotten world again  :lol:

Mike

there are many version of forgotton world, but we want to play on our pce!! :dance:

Still no success for now  :-k I ordered an other HOP-M3 module just in case... Steve, if you happen to find points on duo pcb where i could plug my oscilloscope to see what's going on, that would be great!

Cheers,
   Mike

Quote from: blueraven on 11/20/2010, 08:12 PMAdjusting the Pots:

Advanced Users/Modders only! (unless you really want to risk it...)

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

Tips: The main issue is breaking a pot, or putting it so out of whack the CD player won't read discs at all. Be very gentle, and go SLOWLY when rotating the screwdriver, trying for just a few degrees (out of 360) at a time. This is 20 year-old technology and electrolytic fluid my have weakened the traces. VR102 is the place to start. Please reference BMW's photo below before proceeding.
...
Hopefully this helps, any suggestions are appreciated!

Thanks mate for the guide with a little patience i got mine working after a full recap and laser change thanks again.

i may have some sig names wrong, but scope cal DUO-RX
duo p7
pin
1 4.5V square
2 5V square
3 FE VR103
4 TE VR101  (set to min)
5 RF 30mV
6 trk
7 focus

Hmm, not sure if I'm doing something wrong, but on my Pots, I measured all A-B connections with my multimeter and get the right readings, however nothing else matches (A-C B-C) what am I doing wrong?

here is the best info on scope points (I, may revise/add to)
duo p7
pin
1 4.5V square
2 5V square
3 FE VR103
4 TE VR101  (set to min)
5
6
7


DUO P5 (confirmed correct)

1
2 RF
3 TE
4
5 ASY
6 GND

Hey guys, I want to finally get my Turbo Duo working right.  As of now, the duo will play CD games about 30% of the time depending on the game.  Many times it just spins and spins and doesnt load the game.  Does this mean I should definitely replace the laser? Or if I open up the duo could it be just an adjustment issue or something?  

If I do need to replace it, where can I get a replacement laser?  

Thanks

for starters, clean the tracks and gears
regrease and retest

I thought I would add my two cents on this. After recapping this latest Duo I acquired, I was getting cd audio cut outs, laser whine, etc. Looking over the gears, they did have the tiniest bits of plastic crud built up, which was causing the gears to jam while I was testing. I stripped the gears of all grease, and cleaned the gear teeth with a tooth brush, then re-lubed everything. After all of this I had the nasty whine still, and also, random audio cut outs. I noticed the whine got worse, as did the audio cut outs, the further down the disc the laser had to read. The makes sense, as the laser has to bob and adjust focus more the further down it reads due to disc warping and spin rate adjustments, etc, and not being calibrated right will cause it to lose focus during its eye bobbing up and down.

Unfortunately I don't have a normal pressed music cd that can go the full 80 mins, but I did have a Star Wars Return of the Jedi 2 disc soundtrack set, which happens to have both disc clock in at over 70 mins at least, which I was able to use for helping with adjustments.

Adjustment to any of the pots on the TurboDuo's gave no positive results what so ever. In the end it amounted to me needing to simply adjust the pot on the laser itself. I would play a track or two, if whine persisted, shut down, adjust the pot a tad, turn the unit back on, and test again on the same tracks. No whine, good, no skipping, even better. Move on to the next couple of tracks, rinse and repeat. Eventually I got the whine gone completely from this cd set, and all games mainly except one. It was still present during Image Fight II, especially during the last stage music track, which I would get whine and music cut outs. Due to this, it still needed some slight adjustment still.

Once the laser whine was eliminated from this, it seems everything was about as perfect as can be. No more audio cut outs during the stages music play back (by now it should be no surprise why I beat Image Fight II, I was using it to calibrate the laser, causing me to play the game over and over and over again).  As is, everything seems good to go. I dont play cd-rs on old hardware, so I cant comment on how well they would play back, but so far every cd game I own has been going strong since final adjustments.

Some recommendations I would suggest off hand that I know could be helpful in thorough laser adjustment is the following:
Image Fight II (you can pause the game during gameplay and the music will continue to play, and loop, so it helps to let it sit and loop a track for a good 20-30 mins so you know it can play it without skipping/cutting out)
any pressed music cd that meets or passes the 72 min mark
random games that you can get to play to near the end of the disc music wise (Winds of Thunder/Lords of Thunder is a good candidate for this with its audio tracks being accessible from the option screen and its 19th track being near the end of the disc)

After all of that, its good to just do general gameplay testing. You might run into a oddball game that wasn't pressed as perfect as it could have been, so it might cause a skip or something, making you pop the system back open for a last calibration. The more titles you try out after general calibration, the better off you will be.


Anyway, like I said, just my two cents based on the recent experience. This was not a issue I had run into before with other systems on laser swaps, so, meh, more work and all, but whatever, life goes on.


EDIT: To add to this post, I'd also like to add that after adjusting the lasers pot and eliminating whine, if you are still getting skips past like the 72 min mark on a cd, then I would definitely try slight adjustments to pot VR101. That would be the last thing I would go to adjust focus though, not the first, personally. It also helps to speed things up on your final adjustments if you fast forward through the last 10 mins of the music cd you are using for testing a few times (you may want to alternate between FF'ing through the last 10 mins and also the first 10 mins to make sure its fine tuned on both ends of the spectrum). If still not focusing right, the laser will skip during the fast forward and you will get noise out of the speaker confirming this. You can also set the time counter to total time remaining to help spot the skips easier also just in case. Once you have eliminated these final skips and any laser whine you should be 100 percent set I would think.

Hey guys,

this is my first post in this forum, but I thought it might help anyone attempting to get their Duo/Dou R/Dou RX reading audio soundtracks properly.

Recently I replaced the Hop3 laser lens modules in two Pc Engine Duo Rs and a Pc Engine Duo RX. After replacing the lasers I found that games loaded perfectly but that the cd audio sound tracks would either not play at all, or would start playing and cut out abruptly after a random time period (usually between 5 and 30 seconds).

I assumed this was to do with the 5 resistor pots on the Duo R/RX motherboard, so I followed this guide. I tried measuring the resistance values specified but found my units were very different to the values listed - so different in fact that even by turning the pots to their extreme positions would not bring the resistance value anywhere near the listed values.

So, I tried using the "By Ear" approach. The weird thing is that when I tune the pots on all three Pc Engine Duo machines to the quietest settings, nothing will load any more! :)

Luckily I had marked the original positions of the pots with a sharpie pen.

After spending 3 nights playing constantly with the pots etc I was on the verge of giving up when I noticed the resistor pot on the hop 3 laser module itself. I thought, "why not?" I had tried everything else.

The pot had a drop of resin holding it in its original position, so it took a firm grip with a philips screwdrive to move the pot. I moved it about 5 degrees clockwise  - all of a sudden everything was working perfectly - including all audio soundtracks and even CD-Rs.

I replicated this adjustment to the two other Pc Engine Duos - same result!

At firsst I thought the caps on the motherboards were getting sad and so the adjustment on the laser was compensating for the reduced current being provided by the caps, however on close inspection of all 3 motherboards I can safely say there is NO leaking of ANY caps at all, and since they now run absolutely perfectly I can only assume that the replacement lasers are adjusted in a such a way that the Pc Engine does not like.

I just thought I would share this experience with everyone in case anyone else is experiencing the same problems tuning the Pc Engine Duo.

Hope this helps.

sadly the lasers are now made by several knock-off manufacturers.
they all set them differently, and mostly wrong.
yours were set too low, but ive gotten them set so high they wouldnt read CDR at all

This repair guide rocks! It took me a few days to finally feel comfortable enough to start messing around with the pots on my Duo-r and it totally worked .. No more losing audio at random times .. And it even reads the few cheap quality cdr's I have even better then before .. All it seemed to really come down to is once you find your audio cut out points clockwise and counter clockwise you place a piece of tape on both sides of were it cuts out your audio and center your pot right in the middle of that .. You can always fine tune it after that until you feel satisfied with your adjustment results .. Just be sure to make a tiny little mark on your pots and the board before starting your adjustments, so that you know exactly where they were positioned originally just to be on the safe side .. Thanks a million you guys for contributing all this useful information!

Just wanted to say that I used this guide yesterday and got great results as well.  The only thing is, while adjusting VR101-105 perfected some games, others still had problems until adjusting the pot on the side of the laser, as others have mentioned.  More info here:

https://www.pcengine-fx.com/forums/index.php?topic=14064.msg281184#msg281184

My Duo R recently stopped reading all CD media types.

I have taken measurements at the pots and tried adjusting them to settings specified in this thread but I cannot get even close to the values specified here.

as an example:

VR101:
GOAL:   AB=12.33 AC=10.65 BC=19.55
ACTUAL:AB=12.0 AC=10.2 BC=10.5

As you can see the BC value is only half of the value we are expecting.
I can adjust the pot to get somewhere around 20 for BC but then the values for AB and AC are all out of whack.
I worked on it for hours and could not dial in the right settings.

I have ordered a new laser unit because it can't hurt to have a new laser but I don't think that will solve my problem.

The power supply is the original A/C power supply that came with the system.

Could bad caps be the cause of this? I don't see any obvious issue with the caps.

If it is believed to be the caps... how do I test them and where do I find replacements?

Thanks!

caps are unlikely
yours has a different value pot most likely
your best start point is set how it was working
look for issues with binding first, before trying to adjust pots

Quote from: thesteve on 08/08/2013, 02:19 AMcaps are unlikely
yours has a different value pot most likely
your best start point is set how it was working
look for issues with binding first, before trying to adjust pots

Thanks for the reply.

If I position the unit all the way to the right before power on the unit works it's way inward with no visible impedance after applying power.

I was able to adjust the pots to the pot where the disc spun the entire time between "press run!" and "set disc" but it never actually accepted a disc.

I will try a new laser unit when it arrives.

hey all! 
i bought a Duo-R off a popular ebay seller but am also running into the "CHECK DISC" or whatever error, i bought a power supply from retro game cave so it's not that...seller says i need to tighten a resistor and linked to this guide nifty.com/moremaco/slv.htm (https://web.archive.org/web/20161108214910if_/http://homepage3.nifty.com/moremaco/slv.htm), even sent me a minus screwdriver which was really cool.  a search brought me to this helpful guide as well.

problem is, VR102 looks...damaged ?  i don't see how said screwdriver will catch, i'm grabbing a # 0 phillips head tomorrow but i'm hoping this pic illustrates the problem:

Quote(https://i.imgur.com/k0x2bnX.jpg)

what can i do here?  it showed up like this and i'm not certain if i have enough on the side to maybe catch with a pair of needle nose pliers and adjust that way, or should i try to remove it & replace with something else (assuming that's even an option)? or is it supposed to look like that?  appreciate any help i can get here. 

it's tricky too cause that guide says i cant unplug the short cable on the right side, but there's a short one on the left too that connects to the region switch installed on the hucard slot, i don't think i can remove that either so we're kinda having work around it.

thats how the pots look
look for other reasons first

Also, are you running burns or originals.  These systems have a really hard time reading burned discs.

Quote from: thesteve on 08/11/2013, 12:34 AMthats how the pots look
look for other reasons first

yeah?  it just looks a bit off...okay, guess that's how its supposed to be?
or were you referring to another post?

QuoteAlso, are you running burns or originals.  These systems have a really hard time reading burned discs.

trying original discs, just "PLEASE SET DISC" error previously mentioned in this thread, so far

Ok, my problem has been solved.

In my experience DUO-R do not have a hard time reading CD-R. I was having trouble with CD-R and originals.

I say in my experience because between me and my brother we have 3 of these units.

I purchased a known working DUO-R from ebay (from japan) last week and it arrived today. Coincidentally so did my replacement laser unit (also from ebay).

I had borrowed my brother's DUO-R and over the weekend and tested all my discs on it. No errors or issues playing an disc.

I tested my new DUO-R from ebay and found the results to be the same. Perfect.

I did not want to open his unit because it is working properly and it has a region mod switch and I didn't want to disturb anything.

I opened the new DUO-R and measured the pots. The results are as follows:

VR101
AB:10
AC:9
BC:15

VR102
AB:8
AC:10
BC:12

VR103
AB:6
AC:14
BC:15

VR104
AB:7
AC:10
BC:15

VR105
AB:.5
AC:0
BC:.5

I replaced the laser on broken unit and tuned the pots as close as I could get them. The replacement of the laser unit was unbelievably easy. I couldn't believe it literally took 30 seconds.

The results for the pots were as follows:

VR101
AB:9
AC:10
BC:14

VR102
AB:8
AC:8
BC:12

VR103
AB:4.5
AC:14
BC:14

VR104
AB:15
AC:7
BC:10

VR105
AB:.5
AC:0
BC:.5

The result.... I now have 2 perfectly working DUO-R systems. The inside of the unit from ebay is extremely clean and the hu card slot seems to work perfectly as well.

I guess I will sell one now.

I paid $335 with shipping.

A reasonable offer would not be refused. If anyone is looking for a system.

Thanks for the suggestions, and I hope this info is helpful.

fact is the duo and duo-r have the same drive and with the same laser will read equally well on CDR and originals
that said i have seen more marginal parts on the duo vs the duo-r (likely because its older)

Quote from: thesteve on 08/13/2013, 02:34 AMfact is the duo and duo-r have the same drive and with the same laser will read equally well on CDR and originals
that said i have seen more marginal parts on the duo vs the duo-r (likely because its older)

I can only speak of what I know. I only know about the DUO-R.

I didn't make any comment about the DUO or any other variant.

Quote from: IrishNinja on 08/10/2013, 12:32 AMwhat can i do here?  it showed up like this and i'm not certain if i have enough on the side to maybe catch with a pair of needle nose pliers and adjust that way, or should i try to remove it & replace with something else (assuming that's even an option)? or is it supposed to look like that?  appreciate any help i can get here. 

It looks very damaged.

Take the measurements (if you can) with an ohm meter. Compare them to the measurements I posted.

If they are similar you may want to try a new laser unit.

Adjustment is very fine and needle nose pliers might not do the job. You need to turn just a fraction at a time.

Ok, my CD laser appears to be stuck, all the way on the outside of the track on my OG PCE Duo. The CD won't spin and I tried moving it back manually, and it seems quite stuck. Am I going to have to open her up in order to get everything working I assume?

Also, in some games, especially burns, the audio would randomly cut out, though this did also happen on some of my old retail games that had scratches. I assume I need pot adjustment.

Finally, someone mentioned I need to lubricate the gears on my Duo, I saw something in the OP about lubricating the rails, but nothing about the gears themselves (unless I missed something) What isthe procedure for that?

The og duo can get stuck like that any time its having read issues
You will need to open it and spin the motor gear 2

Quote from: thesteve on 02/17/2014, 09:23 PMThe og duo can get stuck like that any time its having read issues
You will need to open it and spin the motor gear 2

Yeah, opened her up, didn't realize just how much force was going to be needed to spin the gear, the rails seem lubed up and clean already, which is nice, now to mess with the pots. Which pot is it for audio cutting out on a bad read?

Vr104 is focus, Vr103 is focus comp
Vr101 and Vr102 are tracking
Vr105 is spindle comp
Crackle is either focus or tracking
Spindle comp will cause early or late track issues 2

Quote from: thesteve on 02/19/2014, 11:47 PMVr104 is focus, Vr103 is focus comp
Vr101 and Vr102 are tracking
Vr105 is spindle comp
Crackle is either focus or tracking
Spindle comp will cause early or late track issues 2

Any tips for getting the spindle pot working again? I had everything just about perfect then my hand slipped while dealing with vr 105, now I can't get it to read discs anymore, I've been using small increments, as I did with the other pots, but nothing, I'm hearing a clicking, which I assume is the gears, and a high pitched whining at times as well. I wasn't hearing the whine before I screwed up on 105.

Slipped?
Did you hit something with a screwdriver?

If not center the pot and try again 2

Quote from: thesteve on 02/20/2014, 02:06 AMSlipped?
Did you hit something with a screwdriver?

If not center the pot and try again 2

TUrned a little bit farther than I expected. Not TOO far, but clearly enough.

The pots spin all the way around without breaking
Just spin it back
 2

Quote from: thesteve on 02/20/2014, 10:06 AMThe pots spin all the way around without breaking
Just spin it back
 2

That's what I did, it's just refusing to work now, was at it for hours last night.

Appreciate the help though.

Welp, got it working again, it's still giving me hell on a few of the burns I have, but at least my physical games are working. I may open her up again once I am done with a couple of my regular games and see if I can get it working a bit better with burns. The fix, messing a little with VR 102, which I hadn't touched at all for the whole experiment. No idea why that worked, but it at least got me back to being able to read an audio CD, and was then able to follow BlueBMW's tips and even got my scuffed up YS III working, the music in the mines is no longer cutting out on that one at least.

Ok, ready to do what will hopefully be the last adjustments I will need for the pots. Mainly to see if this thing will read CD-Rs well (The discs I burned worked great on Irish Ninja's DUO-R once we got it working. But either won't load, or audio cuts out on mine.) I found an older-ish multimeter to test the resistances, but it is manual. The question I have is that there are several settings for resistance on the thing. It starts at 200ohm, and then goes to 2000, 20k, 200k, and finally 2000k. What should I have it set to to measure the pots? Also, since I'm measuring resistance, it shouldn't matter which color goes on which point correct?

Yeah, this is fairly noobish, but I haven't done much electronics work since around my first year in college and I am rusty as all hell.

Quote from: bishopcruz on 03/17/2014, 05:21 PMThe discs I burned worked great on Irish Ninja's DUO-R once we got it working.

well, that's not true at all, is it?  why, i went to boot up my 3-in-1 and Grand Master Meio killed me good.  :P

Hey everybody,

First poster here, loving the contents of the forum so far. Hope i can contribute to the forums as much as i can.

I recently received my first PC Engine Duo the other day from eBay but it had audio issues and a full recap has seemed to fix the issue  :dance: , but now i got a bit of a problem now with the CD drive. I didn't have any original HuCards or Super CD games on hand so i decided to give a backup a try and the system wasn't reading it well and would boot the game 1/10 times. Afterwards i went to try to make adjustments in small increments with the pots on the motherboard but in the end, i stupidly turned all the pots a good bit and lost track. I normally would busted out my multimeter and used the charts to listed in the first few posts to get back to somewhat normal readings again but i dont know what the 2nd post means by "AB" "AC" "BC". Does anybody what this means?. I have done Gamecube pot adjustments and it was just a simple ohm reading. My multimeter is giving problems so i have to wait intill my next paycheck to get a new one (BK Precision) and also get a new HOP-M3 just in case, but i figured i would ask the necessary questions beforehand so i when i get the multimeter and the new laser, i can know before hand and it bring it back to life and get it running like new again. Can i still revive this PC Engine DUO or is it screwed? :(.

Thank you everybody for their time and patience.

you cant kill anything by turning the main board pots
the pot on the laser can damage the laser

Thank you thesteve,

I managed to get the CD drive working again using a retail disc of Eden of the East. I got CD drive working again by replacing the laser and using the values noted in the link on the 2nd post. I used the last few posts in that thread. I used the DUO-RX readings then used the VR104 value on another post. May need more turning to play CD-R's working but i got audio issues again :(. Got to fix that first.

Hey guys, first post here.

I want play the Castlevania fan translation, so I ripped my original disc and then I applied the patch.

Burned in 10x (minimum possible speed) and tested on my original Duo.
No problems with gameplay, just the audio tracks that play a bit and then stops. Sometimes the Richter  sprite appears garbaged.
The original disc plays without problems, the translated version plays without problems on emulator.

So that means I need to replace cd lens?
Calibrate pots?
Use other cd brand (tried two)?
Change caps?

I would appreciate if someone could help me.

PS: Sorry for my bad english.

Hi,

I've just completed the laser replacement and everything went very smoothly (or so I thought).  However no matter what I do the CD will not spin and eventually I get a Set Disc error.  I did a basic continuity test on the wires and they all seem good at least I think.  On a hunch I put my old laser back in and it also will not start spinning the disc. 

Since both the old and new laser don't seem to be detecting the disc I guess I must have broken something when I removed the laser.  I can't see what I could have damaged as it was very simple and I followed the guide.  Any ideas?

Please take some pictures. I can't think of anything that could have gotten messed up other than some wires getting pulled.

Just to make sure I have this right. Your old lens worked before trying to install a new one but now neither will work?

Yes that's correct.  The old lens not working is what's really stumping me.

Pictures.  Note that the board to the left is a RGB mod and has nothing to do with the laser (everything including the RGB mod was working before I tried to install the new laser).

(https://web.archive.org/web/20190510014000im_/http://www.atariprotos.com/temp/duo3.jpg)
(https://web.archive.org/web/20190510014000im_/http://www.atariprotos.com/temp/duo1.jpg)
(https://web.archive.org/web/20190510013959im_/http://www.atariprotos.com/temp/duo2.jpg)
(https://web.archive.org/web/20190510013959im_/http://www.atariprotos.com/temp/duo4.jpg)

Did you ever at one point try to adjust the pot on the lens itself? If so you should check the contacts for said pot since sometimes turning them can sometimes crack the solder joints.

The points at the start of this thread are great at getting you moving. It would best to start with the best music CD you have to test the new laser.

The cap work on this looks factory quality so that cant be it. Where did you get this "new" laser? I have had my share of "new" old broken, reworked,china CRAP!

I did go through the guide here first, but nothing helped.  I really REALLY don't want to adjust the pots as I hear you can screw crap up that way and they worked with the old laser anyway.  I did play with the pot that supposed to control the CD spindle, but I put it back to where it was after that didn't do anything and the CD wasn't spinning before anyway so I don't think that could have done anything.  I never touched the pots before that.

I got the laser off ebay from the seller a lot of people get theirs from (he's from the USA, that's all I remember).  However if it was a bad laser or pot setting I can't see why the old one wouldn't work, that's the mystery.  To me that points to bad or broken wiring, but I did a continuity test on the wires and they all seem ok as far as I can tell.

I tried a music CD but it still won't spin.  What wires control the CD spinning?

wont spin is an early fail
no cd in
door switch pressed
hit run
the laser sled must bump the center switch, then bob
laser must light
check and report

Yes it does all that.  I assume by 'center switch' you mean the cd spindle?

there is a switch by the spindle the laser sled must hit before looking for the disc

Ok I think I see it.  The sled does bump that switch, but it doesn't look like it pushes it in very far.  I moved the sled over so it totally pushed the switch in, but still no spin.    How much does it normally push that switch in?

EDIT: Looks like that switch just makes the laser go back to the left. I held it in and the laser went all the way the other direction.  So that would make sense if it only bumped the switch lightly and bounced back a bit.

I did a continuity check on the two wires going to that switch.  They seem alright.

next 1 will be harder to see
disc in run
centers, laser bobs 1 time and locks on

It's hard to see, but from what I can tell the laser bobs two or three times before giving up and saying Set Disc.  I don't think it's locking on after one bob.

thats what i suspected
it means its not flagging the mirror pin (cant see its reflection)
possible causes laser/wiring/CXA1081

Ok that's what I suspected as well.  Someone told me that if the laser doesn't detect the disc it won't spin.

Quotepossible causes laser/wiring/CXA1081

I think we can eliminate the laser because even if the new laser was bad, the old laser which worked before is no longer working.  I can't believe I could have damaged it taking it out of the system.

Which wire controls the flagging of the mirror pin?  I thought I tested all the wires in the two ribbon cables and they all tested fine for continuity.  The only one that I'm not sure about is the larger yellow wire that appears to go from the motherboard into a taped up area of the wire bundle.  I don't know where it ends so I couldn't test it for continuity.

Where is the CXA1081?  Is is easily replaceable or is it soldered in?

mirror pin is from the CXA1081
under the board by the connectors
mirror is acheived by the laser sensors responding back to the CXA1081
mirror is sent to the other CXA/CXD chips to switch the system to closed loop
scope pin 2 of connector 5 (P2 of P5) to see the output of the laser/amp

Unfortunately I don't have a scope, just a really crappy volt meter.

I think I've done about as much as I can on my own.   I'm going to send this off to a friend who thinks he can fix it.  I'll report back when I get some news.  I appreciate everyone's help and I'll pass along this info to my friend.

I have a Duo at the moment that is causing problems. This fault existed before capacitors were changed. The fault is still there after all the capacitors have been changed. Will turn on no problems. Will load and play the Hu Card games fine. But removing the card and turning on all I get is a white screen. The interface is just not loading for the CD ROM part. I presume this is chip controlled? Does it mean the chip is dead? Thanks for your help.

its either a dead chip or open connection to a chip
the 22uf caps near the slot are power filters for other sections of the system, check for 5V on them

Do you have the cd system card in?

My bad. Missed the part about it being a Duo.
Still, have you tried with a cd system card?

Thanks for the fast replies! I have checked all the 22uf caps 5 volt on every one. Typically my system card has vanished not in the box! Everything else is fine the laser and all the motors are fine checked in a working console. I also have another one that has the system start up but the laser will not move up and down, again I know it all works tested in a working one so there is something in between stopping the laser. Busy trying to change all the caps! But nothing yet. I have 4 in total but only one working at the moment. Quite frustrating!

find my pinout for the DMA chip, and probe its system bus
odds are you will find a missing signal either there or on the D0-D7 pins at the slot without card

Thanks again. I will try that. Luckily I have found the system card and it works beautifully! So may as well just use it this way if it's not possible to repair the chip?

works with sys card.......that narrows it down

Did a full cap replacement on my Turbo Duo and am gearing up to do my first laser adjustment. Out of the gate, the laser reads audio CD TOC, fires up the first track, plays well, and can track across the disk OK. That probably saves me a lot of pot tweaking.

It seems like the disc and laser might be making contact somewhere between the 30%-50% mark of the disc (inside ring being 0% and outside edge of disc being 100%). After getting a few tracks in, I can hear the disc making contact with something - which alters the rhythm of the spin.

If I track to the end of the disc, I can see what appears to be the laser either "bouncing off" of the disc or having major issues attempting to focus on the track. It spits out several seconds of severely distorted audio, and then returns to center.

I will probably attempt to tweak it today, but I welcome any thoughts from you guys that have done tweaks before. I haven't decided if I want to go to the trouble of hooking my oscilloscope up to it or not.  :-k

look for mechanical binding first

I made an error in my explanation. Instead of the 30%-50% mark being the entire range of the issue, it is actually the approximate starting range where the issue becomes noticeable - the worst being the 100% (last tracks on the disc). Audible laser/lens noise can be heard at about the 50% mark of the disc (smallest degree of focus struggle, perhaps?) The further out on the disc it goes, the more issues it has. If I test the last track, it starts bouncing one or two tracks back and skips a few seconds/chunk of seconds/minute or two forward/backward.

The gears and rods appear to transport the lens OK from what I can tell. I applied the smallest bit of white lithium (spray) to them last night, however I do not think it made a difference.

that sounds like a pot adjustment to me

Seems slightly better. I still have some issues on the later tracks. The spin speed slows on the later tracks, and it seems like the cd gets a slight wobble (when viewed straight on from side of disc) when laser is on the outside tracks.

Thanks for your help.

Glad to see its all going well! I have a DUO-R in the shop as we speak, and will be posting an update on the differences of the two units, and updating the links. Duo_R, could you update the photo links on Page 1? Much obliged!

:D Thanks Guys!

Many thanks to bluebmw for his guide on adjusting pots. After i finished replacing caps on my duo, the cd player still didn't work, so i figured i needed to adjust the pots. They were way out of whack! His guide got me dialed in perfect and everything runs great! Holy shit though, i had to hunt my ass off trying to find a music cd  :lol:

Sup Guys,

i really need your help. after i recaped my duo, the cd unit still played cds with issues. so i bought a new laser and replaced it following this guide. after playing a little bit with the pots, i finnaly got my duo play the cd games almost perfectly without any issues...after some days of not using the duo i just wanted to play some puyo puyo tsu - here the trouble began:

the disc loaded fast as always and at the title screen the music stoped playing. i knew, that my pot settings werent 100% right. i just wanted to try it again and restarted the duo but the disc doesnt move and the laser unit stucked at the very outside. after some trys i managed to move the laser somehow. so i tried to load the game again and same issue...laser moved to the outside and stuck. now i cant get this thing back to the "normal" position.

is there a way to force the laser unit to move back? i spent much money on this duo already, so i want to get it work badly :( hope someone have a nice advice. thx in advance

Spin the gear/motor manually with your finger to get it free again.

Otherwise if it keeps getting stuck this can sometimes be an issue with CD-R discs. Very rare to see it happen with real CDs.

3rd possibility is that your lens motor is going bad. Typically if it gets stuck with real CDs then the motor is bad. I've had to change a few myself so might want to give that a go.

Quote from: Keith Courage on 02/01/2015, 04:43 PMSpin the gear manually with your finger to get it free again.

-_- now that was easy! lol i tried everything except using my fingers :D

thank you!
this console and this forum is awesome!

Ok... i need help.  So, I recently picked up a Turbo Duo that wouldn't play CD's.  It wouldnt spin the CD's at all.  I recapped it and cleaned/lubed the rails, but it still wouldn't spin CD's.  I started the first pot adjustment in BlueBMW's process (VR102) and after a small turn counterclockwise, it started spinning immediately.  In fact it read the music CD that was in it.  I played a few tracks (didnt go all the way to the end, which I regret.  reason why in a minute) and popped in Ys I & II.  It started right up, no problem.

I'm thinking "well, that was easy".    I noticed a bit of a whir sound which I attributed to VR103.  Once again (following BB's instructions), i turned the pot a bit counterclockwise and it diminished a lot.  Then things start to go wrong.  About 5 minutes or so after I started the game, the CD started to speed up a lot.  Per BlueBMWs guide, if this happens he says to adjust VR105.  I started adjusting VR105 and it starts to slow down a bit, then the laser goes all the way to the right and snaps back to the center.  At this point, I figure its been going kind of a while at high speed and I dont want to burn it out, so I shut off the console.  After reviewing BB's instructions again, I probably should have cycled through all the tracks on the CD before switching to the game.

Now no matter what I do to the pots I cant get it to read CD's.  They spin for 13 seconds and then I get the dreaded "Please set Disc!" error.  Fast or slow (depending on how i have the pots adjusted), it always stops at 13 seconds and I get the same message.

Any thoughts?

Ya you gonna need to redo it all again. I actually used a maker to put a dot on the pcb and the pot when its close so you got a reference point at least. Just be patient. I tweaked mine for a good hour before i was completely satisfied. I noticed different games work differently too, for some reason dragon slayer works even when pots are not dead on but adams family was a nightmare as pots had to be fucking tuned to a cunt hair accuracy. Make sure your room is dead silent too so you can really hear the laser. Triple test before you put it back together too lol!

Quote from: cjameslv on 02/08/2015, 09:38 PMYa you gonna need to redo it all again. I actually used a maker to put a dot on the pcb and the pot when its close so you got a reference point at least. Just be patient. I tweaked mine for a good hour before i was completely satisfied. I noticed different games work differently too, for some reason dragon slayer works even when pots are not dead on but adams family was a nightmare as pots had to be fucking tuned to a cunt hair accuracy. Make sure your room is dead silent too so you can really hear the laser. Triple test before you put it back together too lol!

OK.. you inspired me to jump back in.  I believe I am in the sweet spot for VR102 and 104 and probably 103 (not certain because I still cant get it to read CDs).  My point of frustration is VR101.  According to BlueBMW's tips after you get VR102 and 104 in the sweet spot, VR101 comes next.  I interpret the way he wrote it as VR101 adjustment will get it read CD's when its in the right spot.  My problem is, I get no feedback at all when I turn VR101.  It doesn't do anything differently no matter what position its set at.  Its hard to find the sweet spot when you can spin it all the way around without any change in what the laser is doing.

what am i missing here?  how do you know when the laser is just toast?

If V101 doesn't make any change at all then either the V102 is not set incorrectly or the lens gain pot itself is not set correctly.

I set up all my CD lenses by ear.

Quote from: Keith Courage on 02/09/2015, 03:01 PMIf V101 doesn't make any change at all then either the V102 is set incorrectly or the lens gain pot itself is not set correctly.

I set up all my CD lenses by ear.

thanks for the response.  which one is the lens gain?

lens gain pot is the one on the lens itself. Usually the V102 is the culprit though if you cannot get V101 to make any difference whatsoever.

Great guide, thanks for writing this up!

The Hop-M3 is only $13.42 shipped through Aliexpress, and it appears to be the exact same part carried everywhere else. Here (http://www.aliexpress.com/item/HOP-M3-Laser-Lens-Lasereinheit-HOPM3-Optical-Pickup-Bloc-Optique-Replacement-For-DENON-Grundig-Hitachi-Linn/32250829183.html) is the link.

Thanks! I'm just glad that people are utilizing it! I'll update the thread with this as the Laser source!

:mrgreen:

I purchased a PC Engine Duo, knowing that it had no audio.  I'd never gotten my hands on one before, but my best friend was kinda nuts over the TG-16 stuff, and after I bought him a Turbo Everdrive as a birthday gift and watched him go apeshit over it, I kinda got interested myself.

I went through a lot of trouble repairing the Duo, and I have tumbled to some knowledge through a great deal of time, swearing, and frustration that I think others ought to know:


1 - Regardless of how well your Duo works when you get it, replace all caps immediately.  Duos are noted for the poor quality of their caps, and this is not to be understated.  I found that the trace under one of the pre-amp caps was completely destroyed by the cap's failure.  Repairing traces is never a fun thing to do.

2 - When removing the SMT caps, I know a lot of people advocate the 'twist 'em off' method.  Please, for the love of all that is holy, do not do this.  Sure, it's quick, but it only takes one pulled trace to fuck up an expensive piece of vintage technology for good.  Take your time; use a soldering iron to heat up the legs one at a time and gently pull the heated side up.  Inch each leg up a bit at a time, switching sides as needed, until the cap is free.  It'll take time, but better safe than sorry.

3 - Get a frequency counter if you want to adjust VR105.  It doesn't have to be hugely expensive, but you'll need at least a 10MHz model (preferably 20MHz, just to be safe), and you'll need to know how to use it.  I got an old (looks like 70s or 80s model) counter for $15 off of eBay, and it works a treat.  Definitely gonna save up for a scope next.  VR105 adjusts VCO, which needs to be (ideally)4.3218MHz.  Obviously, the closer you get to this value, the better your Duo will run.  I've managed to get it spot-on, and my games load noticeably more quickly. 

• Disconnect the power to your system
• Connect the counter lead (typically the red lead in a red/black pair) to Pin 1 of Connecter P6
• Connect the ground lead (black) to Pin 5 of Connector P5
• Reconnect the power to your system and put a CD (a game works best) on the spindle, and press RUN
• Using a small screwdriver (ideally plastic), adjust VR105 until you get a consistent 4.3-4.4MHz reading.  It's better to go a little high than to be a little low on the reading, so remember that if you can't get it perfect.

4 - One of the problems I encountered that really frustrated me was that CD audio would play decently sometimes, and sometimes it would get scratchy and/or drop out until a new track needed to load.  This is due to either VR101 or VR103.  I recommend going after VR103 first; it's more likely to be your culprit, and unlike VR101, if you take it out of range, it's far less likely to prevent games from loading.  Load up CD game with a sound-test feature (Rondo of Blood is a good choice, because it has an immediately-accessible sound test that will cover the whole range of the CD), and, using Rondo of Blood as an example, select the last music track and play it.  If it crackles or cuts out at any point, use a small plastic screwdriver to make very small movements to VR103.  In my instance, I had to rotate it slightly anti-clockwise, but your mileage may vary. 

5 - One size does not fit all.  I know that there is a rather incomplete Excel matrix of readings off of the trimpots, but when I set my pots to those readings (even the 'average' readings), my Duo kept on failing to load games, playing them with audio errors, or having crazy load times (2-3 minutes to start a game, and sometimes failing to find needed data during an in-game load totally).  Each Duo appears to be a thing unto itself.  Only VR105 requires an absolute value, everything else is...flexible.  This also put me in the awkward position of having to re-determine multiple pots, which brings us to number six...

6 - One pot at a time!  I cannot stress this enough - only work on one pot at a time.  When you think you have that pot correct, test, test again, and test yet again, before going back and testing once more before you even consider moving on to the next pot.  If you fiddle with several things at once, you're far more likely to fuck things up badly, which is why you should always, always, ALWAYS mark the initial setting with a fine-tipped permanent marker or get AB AC BC multimeter readings, so if you do screw the proverbial pooch in your adjustments, you can return to the original settings and try again.

Thanks for the additional info on the pot adjustments, and I'm glat you were able to get your Duo back "On the Road"

Quote from: danyetman on 02/28/2015, 11:25 PM1 - Regardless of how well your Duo works when you get it, replace all caps immediately.  Duos are noted for the poor quality of their caps, and this is not to be understated.  I found that the trace under one of the pre-amp caps was completely destroyed by the cap's failure.  Repairing traces is never a fun thing to do.

I also apply the "Shotgun Method" to replacing caps. Recapping the duo completely is a good idea, but the soundfix will hold in a pinch if you don't have all the caps on hand. Not for the novice...

Quote from: danyetman on 02/28/2015, 11:25 PM2 - When removing the SMT caps, I know a lot of people advocate the 'twist 'em off' method.  Please, for the love of all that is holy, do not do this.  Sure, it's quick, but it only takes one pulled trace to fuck up an expensive piece of vintage technology for good.  Take your time; use a soldering iron to heat up the legs one at a time and gently pull the heated side up.  Inch each leg up a bit at a time, switching sides as needed, until the cap is free.  It'll take time, but better safe than sorry.

=D>
Truer words never spoken. While the "don't twist" part may seem obvious to an experienced repairman, this is a really crucial thing that beginners need to understand before really getting into these units. It's like a bull in a china shop. You can rip the hell out of your traces, and cause major headaches having to bridge them which can cause hours of misery and troubleshooting. BE CAREFUL AND DESOLDER ALL TRACES .

Quote from: danyetman on 02/28/2015, 11:25 PM3 - Get a frequency counter if you want to adjust VR105. VR105 adjusts VCO, which needs to be (ideally)4.3218MHz.  Obviously, the closer you get to this value, the better your Duo will run.  I've managed to get it spot-on, and my games load noticeably more quickly. 

Yes. I use an Ocilloscope to test the pots, but a frequency counter will also work in a pinch.

Quote from: danyetman on 02/28/2015, 11:25 PM4 - One of the problems I encountered that really frustrated me was that CD audio would play decently sometimes, and sometimes it would get scratchy and/or drop out until a new track needed to load.  This is due to either VR101 or VR103.  I recommend going after VR103 first; it's more likely to be your culprit, and unlike VR101, if you take it out of range, it's far less likely to prevent games from loading.  Load up CD game with a sound-test feature (Rondo of Blood is a good choice, because it has an immediately-accessible sound test that will cover the whole range of the CD), and, using Rondo of Blood as an example, select the last music track and play it.  If it crackles or cuts out at any point, use a small plastic screwdriver to make very small movements to VR103.  In my instance, I had to rotate it slightly anti-clockwise, but your mileage may vary. 

An important note, as many people have experienced the audio "cutting out" and have resorted to putting their Duo boards in a dishwasher. I personally have always believed this to be a pot adjustment, and am glad that you are now confirming this, for me at least.

Quote from: danyetman on 02/28/2015, 11:25 PM5 - One size does not fit all.  I know that there is a rather incomplete Excel matrix of readings off of the trimpots, but when I set my pots to those readings (even the 'average' readings), my Duo kept on failing to load games, playing them with audio errors, or having crazy load times (2-3 minutes to start a game, and sometimes failing to find needed data during an in-game load totally).  Each Duo appears to be a thing unto itself.  Only VR105 requires an absolute value, everything else is...flexible.  This also put me in the awkward position of having to re-determine multiple pots, which brings us to number six...

I have also experienced Duo's that have had different settings to run purfectly. My original Duo, the ZombiDuo, which has been repaired about 10 times, is missing two of the trim pots. Hence, the Zombiduo. It still plays fine.

Quote from: danyetman on 02/28/2015, 11:25 PM6 - One pot at a time!  I cannot stress this enough - only work on one pot at a time.  When you think you have that pot correct, test, test again, and test yet again, before going back and testing once more before you even consider moving on to the next pot.  If you fiddle with several things at once, you're far more likely to fuck things up badly, which is why you should always, always, ALWAYS mark the initial setting with a fine-tipped permanent marker or get AB AC BC multimeter readings, so if you do screw the proverbial pooch in your adjustments, you can return to the original settings and try again.

YES. NEVER..... Mess with more than one trim pot at a time. It's like screwing up the firing order in your car by putting your plug wires on wrong.

...and Welcome to the forums. :mrgreen:

Thanks, blueraven.  Some follow-up observations I've made, and a question tied into those observations.

I know I must be reading too much into it, but after I got thing dialed-in, I observed, or appeared to observe, that only the games I'd tried to play while it was having difficulties seemed to load quickly and without problem.  This was limited to my burned copies of Rondo of Blood and Cotton.

Naturally, my first assumption was that my setting were 'not quite right', but I found myself hard-pressed to comprehend that games burned at the same rate and with the same device, using high-quality media, would occupy such different ends of the 'ease-of-playability' spectrum.

I threw in Langrisser, and, out of frustration, simply allowed it to load for as long as it took.  The laser seek went back and forth for quite some time, and then...it loaded!  In shock, I turned it off, and turned it back on.  This time, it loaded faster.  I then started going through different games that I had burned but which had not been able to load.  Faussete Amour, Ys I&II, Ys III, Ys IV...it appeared that the more I attempted to play them, the easier time my Duo had of actually succeeding in playing them.

If the technology were not so limited and antiquated, I would almost believe that the Duo was self-calibrating itself, as it had only been exposed to two games in the weeks previous, and had suddenly had a large selection of very different games in Native English, Patched English, and Unpatched Japanese formats.  I have difficulty in accepting this, but the results appear to speak for themselves.

My question is this:  Is the Duo capable of self-calibration?  Or am I simply witnessing the metaphorical jackalope of the PC Engine world?

Quote from: danyetman on 03/05/2015, 10:02 AMThanks, blueraven.  Some follow-up observations I've made, and a question tied into those observations.

No Problem, glad to share and help :)

Quote from: danyetman on 03/05/2015, 10:02 AMI know I must be reading too much into it, but after I got thing dialed-in, I observed, or appeared to observe, that only the games I'd tried to play while it was having difficulties seemed to load quickly and without problem.  This was limited to my burned copies of Rondo of Blood and Cotton.

Some Duo's have traditionally had problems with burned CD's "Out Of The Box", but I have had reports of some people playing burned games with slightly extended load times.... I will get into that in a minute. I have one Duo that may have been "Adjusted" during the old TurboList days, as it plays burned CD's seamlessly, but has an extended load time across the board, with both original and burned games.

Quote from: danyetman on 03/05/2015, 10:02 AMNaturally, my first assumption was that my setting were 'not quite right', but I found myself hard-pressed to comprehend that games burned at the same rate and with the same device, using high-quality media, would occupy such different ends of the 'ease-of-playability' spectrum.

Your assumptions are correct. From my experience, using a high-end CDR (Like a Black Memorex, Taiyo Yuden, or Mobile Fidelity Sound Lab 24K Gold) burned as a direct copy or 1:1 ratio will work best for preserving the quality of game, and will be less likely to data-bleed in the first few years. I still have a Taiyo Yuden copy of Coryoon that is burned from about 2003, and for some strange reason it still works. It has something to do with what is written during the copy process, I think, because I have had different luck with different burners. It may come down to your hardware, but I can't conform this. An original will ALWAYS work better than a CDR, but you can adjust the pots, supposedly to make burned games work more seamlessly with your Duo.

Quote from: danyetman on 03/05/2015, 10:02 AMI threw in Langrisser, and, out of frustration, simply allowed it to load for as long as it took.  The laser seek went back and forth for quite some time, and then...it loaded!  In shock, I turned it off, and turned it back on.  This time, it loaded faster.  I then started going through different games that I had burned but which had not been able to load.  Faussete Amour, Ys I&II, Ys III, Ys IV...it appeared that the more I attempted to play them, the easier time my Duo had of actually succeeding in playing them.

If this were a Turbo-CD system, I would say that you have a gear issue. Seeing as this is with a Duo, I would put the shortened load time down to the pot adjustments you made. About 12-15 years ago, there was a modder (I forget his name, but Duo_R or D-Lite got a duo from him and reported this to me back in 2008 or 2009) who could "adjust" you duo for about $35-50 so that it would play burned games flawlessly. How this was done remained a mystery on these forums until BlueBMW got into the trim pot adjustments down around the time I created this thread. We concluded that the adjustments were made to the trim pots to get the burned games to work, and thusly incorporated the the trim pot adjustment guide with the "At Your Own Risk" warning. I'm glad your Duo is functional and improving from this information.

Quote from: danyetman on 03/05/2015, 10:02 AMIf the technology were not so limited and antiquated, I would almost believe that the Duo was self-calibrating itself, as it had only been exposed to two games in the weeks previous, and had suddenly had a large selection of very different games in Native English, Patched English, and Unpatched Japanese formats.  I have difficulty in accepting this, but the results appear to speak for themselves.

This is 23 year old technology at this point. I'd be hard pressed to believe that the Duo has a mind of its own, but it is possible. oBey has weird gremlins like that. f you leave it alone for a day or so, does it still "warm up" or was that just a one time thing? It could have been that the Duo "came into calibration" after you adjusted the trim pots, and it reacted to it's new settings.

Quote from: danyetman on 03/05/2015, 10:02 AMMy question is this:  Is the Duo capable of self-calibration?  Or am I simply witnessing the metaphorical jackalope of the PC Engine world?

I think what you saw was you Duo "settling in" to the new parameters you set when adjusting the pots. I'll put the question to the other techies. Thoughts?

All the best with keeping your Duo on the road. :mrgreen:

it does not auto-cal anything
the adjustments do settle a bit so that is likely what you saw
another option is the rails/gears need cleaned and regreased, and were sticking

Thanks for the additional information, blueraven, thesteve.

Firstly, I have already applied white lithium grease to the worm gear and the laser rails.  Handy stuff - I've used it to prevent my original N64 controllers from wearing out, and despite being 19 years old, those controller sticks snap back like new.

Just about the only thing I could do to my Duo is replace the HOP-M3 laser.  I might do that anyway, though I have a horror of re-dialing the pots in again, even if I think it would be a worthwhile experience.

I'm a recent convert to the Church of PCE (having gone the long way 'round, from Nintendo to Sega to Atari to Sony to SNK to NEC), but I'm more interested in the technological side of things, so it occurs to me to wonder about the three connectors (P5, P6, and P7) on the Duo.

Obviously, they are for testing and calibrating the CD functionality.  The trimpots on the board indicate to me that something about the CD's circuit was, shall we say, 'flexible'.  Otherwise, there would be no need to include trimpots for adjusting the laser.  My personal theory is that the lasers themselves have (or had) some pretty wide tolerances, but I can't confirm that.

What I am almost completely certain about is that the P5, P6, and P7 connectors are used in bringing those tolerances into the tight range required for launch-day perfection.  Ergo, there must be some actual required values generated by these connectors that can be brought into conformity with the specs needed for flawless playback of OEM games.  Extrapolating from that, there must be a document related to the practical difference in playability between a pressed disc (of any time, not necessarily a game) and a burned one.

I know this is somewhat stream-of-consciousness here, but unless I am very much mistaken, there must be a document detailing these values.  It would be fascinating to collect and collate all this information...hmm.

your mostly correct
the adjustments are per sony spec, from the chipset datasheets
P5 is your CD cal port
P6 and P7 are data diagnostic ports for troubleshooting a dead drive

If that is the case, then anybody with an oscilloscope and the right documentation should be able to gather absolute values from the P5 connector, is that not so?

So instead of relying on simply listening to the drive itself, we should instead have a guide based off of those absolute values for use with an oscilloscope.

And again, should we not be able to extrapolate values required for burned media as well?

as far as exact values the chipset is designed around a range, and lasers vary
the read values on P5 are different using different media, but not much, so a drive adjusted perfect for CDR runs quite well on pressed.
where CDR is a bit less forgiving of inexact focus or tracking feedback settings
poorly aligned optics on the laser will complicate the tracking/focus causing more difficulty reading

Quote from: thesteve on 03/07/2015, 01:16 AMas far as exact values the chipset is designed around a range, and lasers vary
the read values on P5 are different using different media, but not much, so a drive adjusted perfect for CDR runs quite well on pressed.
where CDR is a bit less forgiving of inexact focus or tracking feedback settings
poorly aligned optics on the laser will complicate the tracking/focus causing more difficulty reading

Fascinating stuff, thesteve.  Mind shooting a link to the documentation on these read value ranges?  And if you can include a no-nonsense primer on how to measure for those values on the P5 connector, that'd be brilliant.

The readings are waveform
Pin1 is ground pin2 is RF
Look up laser eye pattern

Quote from: thesteve on 03/07/2015, 02:16 PMThe readings are waveform
Pin1 is ground pin2 is RF
Look up laser eye pattern

I thought pin 6 on P5 was GND, not pin 1?  Also, I'm not getting any relevant info looking for 'laser eye pattern'.  Perhaps you could be a little more specific?

I found this to be useful: http://www.repairfaq.org/sam/cdfaq.htm#cdgensap (http://www.repairfaq.org/sam/cdfaq.htm#cdgensap)

and this for the eye pattern: http://www.repairfaq.org/sam/cdfaq.htm#cdcdeyep (http://www.repairfaq.org/sam/cdfaq.htm#cdcdeyep)

Quote from: BlueBMW on 03/15/2015, 11:36 AMI found this to be useful: http://www.repairfaq.org/sam/cdfaq.htm#cdgensap (http://www.repairfaq.org/sam/cdfaq.htm#cdgensap)

and this for the eye pattern: http://www.repairfaq.org/sam/cdfaq.htm#cdcdeyep (http://www.repairfaq.org/sam/cdfaq.htm#cdcdeyep)

EXTREMELY helpful!  But, uh, which points on P5 should I tap to adjust this?

EDIT:  Derp.  RF, of course.  Pin 2.  I'm an idiot.

post the pic you showed me of the pattern on your scope bmw

This was from a CDROM2 unit.

/20150316_000814_zps3bynuxmv.jpg

So, to clear this up:

1)  I'm grounding on Pin 1, and pulling the signal on Pin 2.

2)  I'm using non-triggered waveform as the read.

3)  I'm looking for 696ns of separation per half-phase, and 232ns between each wave's equivalent points.

What kind of probe are you using for this?

use a 10X probe
use a triggered input
the data in encoded as a varied wave length, but its done in steps
so what you see is a wave that doesnt directly overlap every pass, but will overlap every few passes
that causes the grid effect

Well, I can't seem to get this right, and now my PCE Duo won't load any CDs at all.

If there's anyone in NA (midwest is close to me) who can tweak this thing back into functionality, I'd be willing to pay a reasonable price for this service.  I don't have the time to coax this troublesome thing back into full operation, and it's frustrating the hell out of me.

Anyone who is able to do this, please PM me.

as long as it spin the scope is useful
from left to right
first 2 adjust for max signal
next pot turn CW till the drive stops, then CCW till it starts again
far right about center
edge of board turn CCW till noise starts and CW till it stops

I don't mean to be critical, but could  you repeat those instructions using the actual VR10(x) numbers, please?  It's a little hard to figure out your meaning.

Pots left to right
102 101 104 105
Edge 103

Nope.  No matter what I do, I can't get it reading CDs again.  Even replaced the HOP-M3 laser with a brand new one.  The most I can get it to do is run silently and have it show the 'please wait' text for some minutes before it says 'Data load error'.

I'm washing my hands of this one, and I could really use someone who is experienced and capable to get it back into working order.  I am beyond frustrated - I am actually quite livid at this.

Quote from: danyetman on 04/11/2015, 11:54 AMNope.  No matter what I do, I can't get it reading CDs again.  Even replaced the HOP-M3 laser with a brand new one.  The most I can get it to do is run silently and have it show the 'please wait' text for some minutes before it says 'Data load error'.

I'm washing my hands of this one, and I could really use someone who is experienced and capable to get it back into working order.  I am beyond frustrated - I am actually quite livid at this.

i understand... i was in the same boat as you and ended up sending it to thesteve.  he ended up re-flowing the solder on the cd controller chips (something i never would have thought of doing) and it runs great now.  not much help, but an endorsement of thesteve's knowledge and abilities.

Oi vey.  I just spent three hours starting from scratch and teasing my Duo into functionality.  I suppose there's a pretty big upside to the frustration I've gone through - my Duo is now working faster and with less noise and greater reliability than it was previously. 

So that's a plus, I guess.

Fair warning:  I'm going to vent for a bit about NEC.

Goddamn it, NEC!  Why the blood-soaked Protestant Hell did you use fucking pots on your boards instead of just creating a circuit that did what it was supposed to in the first place?!  Did it really save that much bloody money by using such a back-asswards design?!

Honest-to-God, what the hell were you thinking?!  Did the engineers just collectively say "Fuck reliability" or was your purchasing manager sleeping with the potentiometer sales rep?  I swear before all gods, living or dead, if I EVER find out the name of the guy who gave the go-ahead on such a shitty design, I will hunt him down, stab in the face with a pastry-knife, set him on fire, and piss on his smokey, still-twitching corpse!!!  You hear me, NEC?  FUCK YOU AND ALL YOUR LOUSY-ARSE SHITEFACED ENGINEERS!!!

Rant over.

*sigh*  Just...eugh.  I hope to the Invisible Pink Unicorn that I never have to tweak a Duo back into life again.

today I had my first experience with a duo recap: black japanese duo with new hop-m3 spins but doesn't read so I replace 4 caps like suggested in doujindance video on youtube, it works but only with one game so I rotate ccw the white pot on the lens assembly and reads more games but I still have some problems with music on some games. should I keep rotating the white pot or maybe start messing with the five small pots on the pcb? after reading this discussion I really do not want to touch those (great thread by the way).

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

The white pot on the lens assembly itself shouldn't be the go-to pot.  VR103 and VR101 will help with your audio issues; sputtering/dropping music is typically a tracking error thing.  Focus on VR103 first.  Make small, and I do mean small, adjustments, and then do something within the game that will cause it to load a new music track.  If the track seems to play fine, then let the new track play a couple of times in a row to make sure.  If it sputters out or disappears, make another small adjustment.  Lather, rinse, repeat.

If you have a frequency counter or an oscilloscope, attach ground to pin 5 of the P5 connector and touch pin 1 of connector P6 with the lead.  With a CD spinning on the spindle, you should get a reading of 4.3-4.4MHz.  If not, turn VR105 until the reading stays within that range.  Ideally, you want 4.3218MHz, but it's better to have it a little high than it is to have it go under 4.3MHz.

Quote from: danyetman on 04/12/2015, 02:25 PMRant over.
*sigh*  Just...eugh.  I hope to the Invisible Pink Unicorn that I never have to tweak a Duo back into life again.

:lol: Thanks I needed a laugh.

I'll add the part about marking the pots when I update the thread next. Good idea and thanks!

after several hours I could have it working with almost all games, but "kiaidan 00" is the most difficult, music won't work during the game shoild I insist on v101 and v103? I also medded with the white pot on the lens, anyone knows the correct impedance for that one? couldn't measure the frequency yet  but I didn't touch v105 after the recap

as a rule dont touch VR105
the other pots depend on the laser assembly, thats why they are pots

Okay, thesteve has pretty much un-idioted me, by which I mean to say that he has taught me very quickly how to use my oscilloscope, which is the greatest tool in the history of ever, and which I consider to be invaluable for anyone attempting to tweak their PCE CD system (whatever it may be) back to life.

Seriously, I can't overestimate how immensely powerful even a cheap scope like mine is.

As far as the white lens pot is concerned, most of them should come with a hard epoxy on the pot, locking it in the factory-determined ideal impedance.  That being said, it's okay to have it 'too strong'.  Sure, it'll shorten the lifespan of the laser itself, but better overpowered than underpowered.

VR105, as I've said before, should be clocked at a fairly precise 4.3MHz frequency.  Because the very nature of a waveform is its undulation, you're going to get readings at both the top and the bottom of the waveform, meaning you'll see the frequency go up and down on your meter.  As a rule of thumb, try to get the frequency of VR105 to go NO LOWER than 4.321MHz, which should mean your peak should be at 4.400MHz, or more likely just under.  Again, better a little strong than a little underpowered.  A decent frequency counter (at least 10MHz) shouldn't cost you more than $15 USD on eBay, and is well worth the investment.

VR103 is your go-to pot if you have scratchy sound or sound that drops out.  On all the Duos I've played with, it seems to have a very, very small window of perfect operation - maybe ten degrees or so, but I'm not sure if this is typical, as my sample group is comprised of the four Duos (all PCE) I have ever seen.

If you're starting from scratch on adjusting the pots, thesteve's directions are perfect:

1)  Pull the RF signal from pin 2 on the P5 connector, and ground it on pin 1 of P5.
2)  Set your scope to 2.00V/Div and 1.000us/Div.  Get your readings while your CD system is trying to load the disc.
3)  While the CD attempts to load, use a plastic or other non-metal small Phillips-head screwdriver to turn VR102.  You're trying to get the greatest amplitude (biggest wave) you can.  Once you've found the spot that makes the wave as large as it can be, move on to VR101 and do the exact same thing.
4)  After you've made the biggest wave you can, set your scope trigger to be at the far left of your screen, and about 3/4 of the way up the waveform you're pulling.  Turn VR104 clockwise until the disc stops spinning.  Once this happens, make the smallest turns you can COUNTER-clockwise and wait a few seconds between each turn to see if the disc starts spinning.  Once it does, move on to VR103.
5)  VR103 is kind of the odd pot out - it's incredibly touchy, and it seems to vary on a per-Duo basis how to set it.  Ideally, you want to turn it until your drive is making no real noise - no squeaks, no whines, no chugs or repetitive clicking noises.  It should run almost silently.  You can find your starting point by turning it counter-clockwise until it starts making a faint whine-like noise.  When this happens, turn it CLOCKWISE by a hair, and I do mean 'just a hair'.  I'm not exaggerating when I say that the VR103 pot has a very small window of operation.  Use a game with a soundtest available right off the bat, like Rondo of Blood.  Playtest the first and last tracks while making minute adjustments.  There should be no crackling or audio dropouts at all.  This can take some time, so be patient, and you'll pull through.

i set my trigger first
as for the pot on the laser if its too high it causes errors in the focus/tracking circuit
after everything is set adjust the laser pot so your wave is between 0.7Vpp and 1Vpp
it will vary a bit with different media so check it on a few different types of disc if possible

Thank you for the detailed instructions danyetman and thesteve, I fixed my duo! now it seems to read everything and the music plays fine. BUT I noticed while the music is on the sound effects are very very low. is this a common issue? could it be a cap? if I play hucards I hear the audio just fine.

it could be cap related
there is a mixer circuit that uses cap charge to adjust the mix levels

Quote from: thesteve on 04/19/2015, 04:15 AMit could be cap related
there is a mixer circuit that uses cap charge to adjust the mix levels

I want to recap that section, can you point me at which caps could be related to the issue?

I will go out on limb here and suggest robotype that if you do open up the Duo you should do a full cap replacement on the system. It will only get worse over time if you don't.

Of all the research I have done on the subject from threads on these forums it is in you're best interest to replace all caps on any Duo's if they have not been replaced already. I am not a guru here so second opinions are welcome. I recently did my own Duo and it's like a new machine again.

I opened the duo many times it's very quick I want to try and replace only the caps related to the audio mixing section before the full recap (which I will certanly do when I get the full cap kit)

You're wasting your time only doing a few caps at a time.  There aren't that many total, just do them all, wash the board good (dishwasher does the trick) and enjoy the duo for years to come.

I promise you I will do the full recap but just out of curiosity, if someone knows it, which are the caps related to the audio mix?

The 2 SMD caps behind the heatsink on the right
They leak so cleaning the area is as important as the parts

Quote from: thesteve on 04/19/2015, 03:09 PMThe 2 SMD caps behind the heatsink on the right
They leak so cleaning the area is as important as the parts

great! thanks

ok I replaced the two smd behind the heatsink on the right and didn't help, so I replaced the two in front but nothing changed so I recapped the whole thing and now I hear sound effects loud and clear. I think the two caps related to the mixing are the two on the right (near the cd player).

my duo now plays anything perfect (only original games, I don't have CD-Rs)

these are my impedance readings

101 AB  7.3  AC 13.4  BC 19.1
102 AB  8.6  AC  7.8   BC  9.9
103 AB 15.9 AC  2.5   BC 17.8
104 AB 19.4 AC  1.7   BC 20.3
105 AB 0.00 AC  0.36 BC 0.36

I didn't measure the white pot on the lens

Quote from: BlueBMW on 04/19/2015, 01:32 PMwash the board good (dishwasher does the trick)

*throws hands up in exasperation*  Why on God's green earth does everyone give this horrible piece of advice?  This is probably one of the worst things you could do!  Dishwashing detergents are overwhelming alkaline in nature, which will cause corrosion on metallic surfaces on an epic scale if even the slightest bit remains.

In addition, some of the more aggressive dishwashers are fully capable of pulling SMT components off of boards.

If you want to clean a board properly, use non-alkali degreaser, a soft/medium toothbrush, and do it by hand in the sink.  Then spray the thing down with 90% Isopropyl alcohol and let it air-dry over the course of 3-5 days in low humidity.

I have washed dozens if not hundreds of boards this way and all are still in great operation today.  I work in a circuit board manufacturing plant and guess what we basically use to wash our boards, industrial dishwashers with very similar detergents to what you use at home.  Use very little detergent and you dry the board with an oven.   What I do at home is essentially the same as what I do at work.  And the stuff I build at work goes into satellites, spaceships and weapons.

Scrubbing by hand is great until you miss leaked electrolytic fluid under a chip or in a via that you cant get out with simple scrubbing with a toothbrush.  I know. I used to do it that way... 99% isopropyl and a toothbrush.  Even after that some boards would still have issues.  After a dishwasher wash and oven dry they work perfectly.

Is there some risk with washing them in a dishwasher?  Of course, but I think the risk is far less than leaving leaked electrolytic fluid stuck in some vias or under chips causing a slow death of the traces it touches.

You know who I learned this technique from?  None other than thesteve whom you praise in your signature.

Here's a pic for posterity...

X68000 Compact Mainboard going in for a wash :)  Computer came out great and works awesome still to this day.

/Crazy_zps67178b9d.jpg

Quote from: danyetman on 04/28/2015, 01:20 PM*throws hands up in exasperation*

Throw your hands in the air like you just don't care..... because nobody here cares what you think.  :dance:

Quote from: danyetman on 04/28/2015, 01:20 PM

Quote from: BlueBMW on 04/19/2015, 01:32 PMwash the board good (dishwasher does the trick)

*throws hands up in exasperation*  Why on God's green earth does everyone give this horrible piece of advice?  This is probably one of the worst things you could do!  Dishwashing detergents are overwhelming alkaline in nature, which will cause corrosion on metallic surfaces on an epic scale if even the slightest bit remains.

In addition, some of the more aggressive dishwashers are fully capable of pulling SMT components off of boards.

If you want to clean a board properly, use non-alkali degreaser, a soft/medium toothbrush, and do it by hand in the sink.  Then spray the thing down with 90% Isopropyl alcohol and let it air-dry over the course of 3-5 days in low humidity.

I think you have no idea how the fuck this has been common practice in the professional electronic repair field for years now for both arcade vendors and computer repair shops. Also, why would you just spray alcohol  all over a pcb and let it sit. What magical process do you think the alcohol does on its own with no human interaction as it dries?

The alcohol, Mr. Attitude, is used to assist evaporation of the water in order to assure that there's no water left in or on components when it's next powered up.

And for the record, 'common practice' /= 'good practice'.  It is 'common practice' (or was in the 80s and 90s, at least) to blow on NES cartridges when they didn't make a good connection.  However, we know now that this was a placebo fix, and in fact assisted in corrosion of the cartridge pins thanks to the moisture of the blower's mouth. 

Now tell me something - is it 'common practice' to get pissed off and start swearing at someone when you clearly didn't read the entirety of my post?  I quote from my immediately previous post:

If you want to clean a board properly, use non-alkali degreaser, a soft/medium toothbrush, and do it by hand in the sink. Then spray the thing down with 90% Isopropyl alcohol and let it air-dry over the course of 3-5 days in low humidity.

Yet all you focus on is the alcohol, to the exclusion of all else.  In fact, you take that single statement completely out-of-context and treat it as if I prescribed that as the sole remedy, completely missing everything leading up to that.

Next time you want to get pissy about something, do yourself a favor and make sure you know what the hell you're responding to, genius.

You don't need alcohol to dilute water to assist in drying. All you need is patience, warmth, a small enclosed space you can prop the boards upright in, and a fan. Its called making a drying station. Stop being a lazy fuck trying to act like a know it all pro. You can save the alcohol for actual spot cleaning moron. All you are doing is....lol pouring money down a drain, figuratively speaking.

As for washing boards, its been done in factories and in small repair shops for years now. You have the option to use a cleaning agent or not. Usually just an extended and thorough powerful wash of warm water will do the trick in many cases. You acting horrified at the fact we do this is laughable. It shows how clueless you have been to how this stuff is done on a professional level since jump street.

Scrubbing by hand does not get into nooks and crannies and expose trace damage the way a good wash will. I have done game system, arcade, computer pcbs, and pc power supplies this way for years now with no issue. I have yet to see anything damaged by a wash. No components ever broken off or damaged. What I have done is spot old damage after said wash so I can repair it while avoiding wasting hours of my time trying to pick out bits of crud and corrosive material I missed from a tooth brush scrub.

I'm sorry you don't get that. But hey, just keep your methods to yourself, and shut up when grown folks be talking. Don't like the "attitude"? Fine, leave then. We dont suffer fools around here.


Side note, since we are on the topic of cleaning pcbs, because there is actually dumb fucks out there that do this, for god's sake don't clean them off with shit like WD40. I have seen the damage that kind of shit does. It isn't pretty.

Holy crap, where was I on this thread?

Hello, before touching something i would like to ask here.
My DUO black is doing "please set disk" when i put a game disk. Audio disks work but sometime audio goes bad. Is it a Caps problem or a calibration lens problem?
Thanks

If the caps havent been done yet then I would start there.  I've seen bad caps affect CD playback for sure.

Quote from: BlueBMW on 06/01/2015, 12:32 PMIf the caps havent been done yet then I would start there.  I've seen bad caps affect CD playback for sure.

I understand. Don't you think pot calibration can resolve the problem? is risky to do before caps?

I would leave the pots alone until you do the caps.  It may be possible to adjust the pots to compensate but some of the caps affect the operation of the laser.  I have had several duos that didnt read discs before a cap job start working perfectly aftewards with no adjustment.

Quote from: Chester77 on 08/13/2013, 12:32 AMOk, my problem has been solved.

In my experience DUO-R do not have a hard time reading CD-R. I was having trouble with CD-R and originals.

I say in my experience because between me and my brother we have 3 of these units.

I purchased a known working DUO-R from ebay (from japan) last week and it arrived today. Coincidentally so did my replacement laser unit (also from ebay).

I had borrowed my brother's DUO-R and over the weekend and tested all my discs on it. No errors or issues playing an disc.

I tested my new DUO-R from ebay and found the results to be the same. Perfect.

I did not want to open his unit because it is working properly and it has a region mod switch and I didn't want to disturb anything.

I opened the new DUO-R and measured the pots. The results are as follows:

VR101
AB:10
AC:9
BC:15

VR102
AB:8
AC:10
BC:12

VR103
AB:6
AC:14
BC:15

VR104
AB:7
AC:10
BC:15

VR105
AB:.5
AC:0
BC:.5

I replaced the laser on broken unit and tuned the pots as close as I could get them. The replacement of the laser unit was unbelievably easy. I couldn't believe it literally took 30 seconds.

The results for the pots were as follows:

VR101
AB:9
AC:10
BC:14

VR102
AB:8
AC:8
BC:12

VR103
AB:4.5
AC:14
BC:14

VR104
AB:15
AC:7
BC:10

VR105
AB:.5
AC:0
BC:.5

The result.... I now have 2 perfectly working DUO-R systems. The inside of the unit from ebay is extremely clean and the hu card slot seems to work perfectly as well.

I guess I will sell one now.

I paid $335 with shipping.

A reasonable offer would not be refused. If anyone is looking for a system.

Thanks for the suggestions, and I hope this info is helpful.

Thanks Chester77 this worked for me and my Duo-r is reading every stubborn disk i have.

I would setup using counters and scopes but thought I'd try this first and it reading so quick now.

Quote from: danyetman on 04/14/2015, 03:05 AMOkay, thesteve has pretty much un-idioted me, by which I mean to say that he has taught me very quickly how to use my oscilloscope, which is the greatest tool in the history of ever, and which I consider to be invaluable for anyone attempting to tweak their PCE CD system (whatever it may be) back to life.

Seriously, I can't overestimate how immensely powerful even a cheap scope like mine is.

As far as the white lens pot is concerned, most of them should come with a hard epoxy on the pot, locking it in the factory-determined ideal impedance.  That being said, it's okay to have it 'too strong'.  Sure, it'll shorten the lifespan of the laser itself, but better overpowered than underpowered.

VR105, as I've said before, should be clocked at a fairly precise 4.3MHz frequency.  Because the very nature of a waveform is its undulation, you're going to get readings at both the top and the bottom of the waveform, meaning you'll see the frequency go up and down on your meter.  As a rule of thumb, try to get the frequency of VR105 to go NO LOWER than 4.321MHz, which should mean your peak should be at 4.400MHz, or more likely just under.  Again, better a little strong than a little underpowered.  A decent frequency counter (at least 10MHz) shouldn't cost you more than $15 USD on eBay, and is well worth the investment.

VR103 is your go-to pot if you have scratchy sound or sound that drops out.  On all the Duos I've played with, it seems to have a very, very small window of perfect operation - maybe ten degrees or so, but I'm not sure if this is typical, as my sample group is comprised of the four Duos (all PCE) I have ever seen.

If you're starting from scratch on adjusting the pots, thesteve's directions are perfect:

1)  Pull the RF signal from pin 2 on the P5 connector, and ground it on pin 1 of P5.
2)  Set your scope to 2.00V/Div and 1.000us/Div.  Get your readings while your CD system is trying to load the disc.
3)  While the CD attempts to load, use a plastic or other non-metal small Phillips-head screwdriver to turn VR102.  You're trying to get the greatest amplitude (biggest wave) you can.  Once you've found the spot that makes the wave as large as it can be, move on to VR101 and do the exact same thing.
4)  After you've made the biggest wave you can, set your scope trigger to be at the far left of your screen, and about 3/4 of the way up the waveform you're pulling.  Turn VR104 clockwise until the disc stops spinning.  Once this happens, make the smallest turns you can COUNTER-clockwise and wait a few seconds between each turn to see if the disc starts spinning.  Once it does, move on to VR103.
5)  VR103 is kind of the odd pot out - it's incredibly touchy, and it seems to vary on a per-Duo basis how to set it.  Ideally, you want to turn it until your drive is making no real noise - no squeaks, no whines, no chugs or repetitive clicking noises.  It should run almost silently.  You can find your starting point by turning it counter-clockwise until it starts making a faint whine-like noise.  When this happens, turn it CLOCKWISE by a hair, and I do mean 'just a hair'.  I'm not exaggerating when I say that the VR103 pot has a very small window of operation.  Use a game with a soundtest available right off the bat, like Rondo of Blood.  Playtest the first and last tracks while making minute adjustments.  There should be no crackling or audio dropouts at all.  This can take some time, so be patient, and you'll pull through.

Few questions about scopes / frequency counters:

- would scopes like this would do the job?:

http://www.ebay.fr/itm/Kit-Oscilloscope-DSO138-2-4-TFT-numerique-DIY-Parts-Set-electronique-1Msps-/131538450791?hash=item1ea04d7967:g:CREAAOSw37tWA5z- (http://www.ebay.fr/itm/Kit-Oscilloscope-DSO138-2-4-TFT-numerique-DIY-Parts-Set-electronique-1Msps-/131538450791?hash=item1ea04d7967:g:CREAAOSw37tWA5z-)

- If yes, Do I still need a FC like this for VR105?:

http://www.ebay.fr/itm/KKmoon-Frequence-de-loscillateur-cristal-MHz-50-Counter-testeur-Kit-0WN8-/181825855970?hash=item2a55aa61e2:g:-xYAAOSwpdpVXeAq (http://www.ebay.fr/itm/KKmoon-Frequence-de-loscillateur-cristal-MHz-50-Counter-testeur-Kit-0WN8-/181825855970?hash=item2a55aa61e2:g:-xYAAOSwpdpVXeAq)

-If not, what type/model of scope would be required to set/verify  lasers on Duos/CDromroms ?

fact is the DSO may or may not, as nobody has tried one yet
you will never need the FC for VR105

Thanks for answering Thesteve.  :)

This made me think afrequency counter would be usefull for VR105:

Quote from: danyetman on 04/14/2015, 03:05 AMVR105, as I've said before, should be clocked at a fairly precise 4.3MHz frequency.  Because the very nature of a waveform is its undulation, you're going to get readings at both the top and the bottom of the waveform, meaning you'll see the frequency go up and down on your meter.  As a rule of thumb, try to get the frequency of VR105 to go NO LOWER than 4.321MHz, which should mean your peak should be at 4.400MHz, or more likely just under.  Again, better a little strong than a little underpowered.  A decent frequency counter (at least 10MHz) shouldn't cost you more than $15 USD on eBay, and is well worth the investment.

The fact is I already have a DIY scope like the one I linked, but the screen arrived broken. I've been refund, but now I hesitate to buy a new one, especially if it's useless for PcE lasers.

think of VR105 like the V-Sync knob on the old TV
it sets an oscillator slope, that needs to be reset by the CD data before it reaches its freq setting
if its too low it could pickup harmonics, but set too fast it will cut the data frames short and fail to read the disc

Got a few questions here
I just recently got around to capping my duo,(I decapped it after I got it a few years back but never got around to the recap :( ) its running good now :) and I also just fixed the high pitched ringing noise by adjusting pot 102 a quarter turn cc like mentioned here
https://www.pcengine-fx.com/forums/index.php?topic=3586.msg122549#msg122549 (https://www.pcengine-fx.com/forums/index.php?topic=3586.msg122549#msg122549)

Just wondering when should you replace the laser? what are the problems the lasers start to have?

Also about putting the board in the dishwasher, Is it ok to do this with the new caps and all?
And what about dishwasher settings and the hot steam dry is this all ok?
for oven drying what temp do you want and how long.. can I bake at the same time?

I had trouble with a few pads that must have had old capfluid or something in the old solder, ended up hitting them a few times (possible burning the stuff away) before I got some solder on the board but they look a little dirty, is this going to be ok? or should I redo them and try and get rid of the old solder?  (I'm a bit of a novice and have only done minor soldering here and there)

washer is fine, normal settings (anything loose may come loose so be aware of it)
as far as laser failure it happens several ways
some wont read certain discs, where others just stop reading
some work for awhile and stop, then work again later

It's been a long time since I took the screws out of my PCE DUO, and I seem to have "misplaced" them.  I always planed on replacing those torx #10 screws, one of which stripped and was a complete bitch to get out, with regular Phillips once the thing was complete.  I tried looking for "#40 1/2" pan" but never found anything that looked right.  So for instance, is http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7 (http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7) correct?  They look far too long to me.

Quote from: SegaSonic91 on 01/12/2016, 06:06 PMIt's been a long time since I took the screws out of my PCE DUO, and I seem to have "misplaced" them.  I always planed on replacing those torx #10 screws, one of which stripped and was a complete bitch to get out, with regular Phillips once the thing was complete.  I tried looking for "#40 1/2" pan" but never found anything that looked right.  So for instance, is http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7 (http://www.ebay.com.au/itm/Qty-5-Pan-Head-Machine-4-40-UNC-x-1-2-Stainless-SS-304-Screw-Phillip-Bolt-BSW-/231669035899?hash=item35f08cf37b:g:jPoAAOSwMmBV4HC7) correct?  They look far too long to me.

They probably have a generic picture there.  The screws you need are some type of course thread. I have not ever measured them though but that is definitely the wrong kind of screw and wrong thread.

edit:
i did a rough measurement.  They do look close to a #4 so im guessing its actually an M3 and they are about 12mm long.  This is my best guess as to the size.  not 100% sure this is correct though
http://www.ebay.com/itm/20X-M2-M5-304-Stainless-Round-Head-Phillip-Pan-Head-Flat-Tail-Self-tapping-Screw-/171951921628 (http://www.ebay.com/itm/20X-M2-M5-304-Stainless-Round-Head-Phillip-Pan-Head-Flat-Tail-Self-tapping-Screw-/171951921628)
black
http://www.ebay.com/itm/100PCS-M3-M4-M5-Philips-Round-Head-Screw-Self-Tapping-Horizontal-Tail-Bolt-Black-/272013654380 (http://www.ebay.com/itm/100PCS-M3-M4-M5-Philips-Round-Head-Screw-Self-Tapping-Horizontal-Tail-Bolt-Black-/272013654380)

can maybe find those locally or a cheaper listing on ebay with less quantity

edit again:
updated the link with ones that have the same flat bottom

Quote from: mickcris on 01/12/2016, 06:29 PMcan maybe find those locally or a cheaper listing on ebay with less quantity

Phillips Pan Metal Screws: #4 x 1/2in available in 100 packs at ACE Hardware for just over $12

If you send me an address, Segasonic91 I can send you 5. I always have a box of these lying around.

Good link Mickcris, the only thing that would be in question is the length. 1/2" is appropriate, and 5/8" will work is the bolt is stripped, but I wouldn't go any longer or shorter here. The Duo wont close properly.

Quote from: blueraven on 01/13/2016, 03:51 PM

Quote from: mickcris on 01/12/2016, 06:29 PMcan maybe find those locally or a cheaper listing on ebay with less quantity

Phillips Pan Metal Screws: #4 x 1/2in available in 100 packs at ACE Hardware for just over $12

If you send me an address, Segasonic91 I can send you 5. I always have a box of these lying around.

Good link Mickcris, the only thing that would be in question is the length. 1/2" is appropriate, and 5/8" will work is the bolt is stripped, but I wouldn't go any longer or shorter here. The Duo wont close properly.

I measured again and the OG screw threads are exactly 12 mm long.  They have them in 14mm also if you want some longer ones.  I am assuming, since these systems were made in Japan, the screws are metric.  12mm is 0.472441 inches and 14mm is 0.551181 inches.  Im not sure from his post if the head is stripped or the inside of the hole.  The ones you are using may have that split in the end which makes less threads where the ones i have linked have threads the whole way to the bottom like the originals.  like this one that will not hold as good cause of its end:
http://www.homedepot.com/p/Everbilt-8-x-3-4-in-Zinc-Plated-Self-Drilling-Pan-Head-Phillips-Drive-Sheet-Metal-Screw-100-Piece-per-Pack-801042/204275119 (http://www.homedepot.com/p/Everbilt-8-x-3-4-in-Zinc-Plated-Self-Drilling-Pan-Head-Phillips-Drive-Sheet-Metal-Screw-100-Piece-per-Pack-801042/204275119)

I was only not sure about the M3 size but I think its coorect

Here is what I'm using:

(?action=dlattach&topic=8926&attach=4812&image) (https://i430.photobucket.com/albums/qq21/Rookstower/Video%20Games/repairs/IMG_3623_zpsuneczzxx.jpg)

Quote from: mickcris on 01/13/2016, 04:40 PM

Quote from: blueraven on 01/13/2016, 03:51 PM

Quote from: mickcris on 01/12/2016, 06:29 PMcan maybe find those locally or a cheaper listing on ebay with less quantity

Phillips Pan Metal Screws: #4 x 1/2in available in 100 packs at ACE Hardware for just over $12

If you send me an address, Segasonic91 I can send you 5. I always have a box of these lying around.

Good link Mickcris, the only thing that would be in question is the length. 1/2" is appropriate, and 5/8" will work is the bolt is stripped, but I wouldn't go any longer or shorter here. The Duo wont close properly.

I measured again and the OG screw threads are exactly 12 mm long.  They have them in 14mm also if you want some longer ones.  I am assuming, since these systems were made in Japan, the screws are metric.  12mm is 0.472441 inches and 14mm is 0.551181 inches.  Im not sure from his post if the head is stripped or the inside of the hole.  The ones you are using may have that split in the end which makes less threads where the ones i have linked have threads the whole way to the bottom like the originals. 

I was only not sure about the M3 size but I think its coorect

I assume that you are correct about the metric sizes versus standard, I will say that this was a suitable alternative for the time being, but I was wondering about the pitch of the threads. I have had some cases where repetition of removal/install has broken down the posts and left the system running with 4/5. They do have threads going all the way down though. I could look for the metric equivalent.

they are self tapping so the the original screw cut the threads. Not sure if the metric and standard thread pitch is the same so using those ones could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

edit:
those ones you have do have that point at the end which is counted in the length.  that part of the screw is not going to be doing anything.  so that is going to make the threads maybe about a mm shorter.

Yikes, I never shop at ACE Hardware unless I just need something in the dollar range...

Got ripped off so bad there on so many things compared to what I saw when Menards and Home Depot came around... They're the absolute worst with the highest prices on everything.

Quote from: NightWolve on 01/13/2016, 06:02 PMYikes, I never shop at ACE Hardware unless I just need something in the dollar range...

Got ripped off so bad there on so many things compared to what I saw when Menards and Home Depot came around... They're the absolute worst with the highest prices on everything.

Yeah they are. The place I went to years ago had a 25% off sale which made them about the same price as Harbor Freight.

Quote from: mickcris on 01/13/2016, 05:37 PM...could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

The threads lined up perfectly (or so I thought) when I checked the screws against the Safety bits that came out of the Duo. Most of the systems haven't broken a post due to this issue, rather the brittle nature of the plastic and having been opened up too many times. Also, yes, I do turn them CCW before insall to make sure that they are seated.

Quote from: mickcris on 01/13/2016, 05:37 PM...so that is going to make the threads maybe about a mm shorter.

On the bottom end, yes. I hadn't thought of that.

Quote from: blueraven on 01/13/2016, 07:35 PM

Quote from: mickcris on 01/13/2016, 05:37 PM...could possibly be damaging the holes if they are not the same.    You need to make sure the screw is going into the originally cut threads or it will strip out the hole.  I use the method that game-tech-us was recommending in one of his videos where you turn the screw ccw till you feel it go back into the hole and then start going cw.

The threads lined up perfectly (or so I thought) when I checked the screws against the Safety bits that came out of the Duo. Most of the systems haven't broken a post due to this issue, rather the brittle nature of the plastic and having been opened up too many times. Also, yes, I do turn them CCW before insall to make sure that they are seated.

Quote from: mickcris on 01/13/2016, 05:37 PM...so that is going to make the threads maybe about a mm shorter.

On the bottom end, yes. I hadn't thought of that.

Yeah, I think sometimes there is nothing you can do to stop them from stripping out the threads in the hole.  I looked it up and it seems like M3 may be a hair larger diameter than #4 so that could maybe also be a factor. Not sure if it's enough to make a difference. I'm pretty sure now that those ones I linked to are the same size as the originals.

Never mind. Wrong ones you were talking about.

snip

Quote from: guest on 06/20/2016, 09:09 PMI've been doing some adjustments (with the aid of a multimeter to be able to record "default" values) and nothing was really working for CDRs until I got enough courage (or was stupid enough) to mess with the LASER pot. I did less than 10 degrees clockwise and finally a lot of games on CDR started to work flawlessly! Lords of the Rising Sun and Raiden are two of which I'm now enjoying.

Quite oddly, my silver 650MB Mitsuis are not working, but a cheap ass CDR (by Ritek) works very well lol, so much for superior CD quality. The cheapo discs are less "transparent" than the 650mb discs so it might be the reason for working well. I've solved ALL problems, except for...

Yeah, it has problems when seeking late tracks. As you can see in the video (please excuse my sloppy disc handling :P), Riot Zone "boots" but it immediately tries to read a late track on the disc. The laser goes to the edge, the CD spins at max speed, and nothing works. This also happened with my Mitsuis when they used to work (I don't have any spare ones anymore so I cannot do further testing). I never observed any issues with pressed discs (official ones or repros from the King of Scanline Generators).

What pots should I focus on (if at all)? I'm quite frankly tired of doing trial and error with them.

If you only have a multimeter check out page 5 if this very thread. Chester77 listed default vaules. They work very well in most systems I have tried them on.

Quote from: MNKyDeth on 06/21/2016, 09:42 AM

Quote from: Psycho Punch on 06/20/2016, 09:09 PMI've been doing some adjustments (with the aid of a multimeter to be able to record "default" values) and nothing was really working for CDRs until I got enough courage (or was stupid enough) to mess with the LASER pot. I did less than 10 degrees clockwise and finally a lot of games on CDR started to work flawlessly! Lords of the Rising Sun and Raiden are two of which I'm now enjoying.

Quite oddly, my silver 650MB Mitsuis are not working, but a cheap ass CDR (by Ritek) works very well lol, so much for superior CD quality. The cheapo discs are less "transparent" than the 650mb discs so it might be the reason for working well. I've solved ALL problems, except for...

Yeah, it has problems when seeking late tracks. As you can see in the video (please excuse my sloppy disc handling :P), Riot Zone "boots" but it immediately tries to read a late track on the disc. The laser goes to the edge, the CD spins at max speed, and nothing works. This also happened with my Mitsuis when they used to work (I don't have any spare ones anymore so I cannot do further testing). I never observed any issues with pressed discs (official ones or repros from the King of Scanline Generators).

What pots should I focus on (if at all)? I'm quite frankly tired of doing trial and error with them.

If you only have a multimeter check out page 5 if this very thread. Chester77 listed default vaules. They work very well in most systems I have tried them on.

they don't work on mine.
Did final adjustment to 104 since my original Buster Bros. didn't work, now all discs work like a charm (with the exception of problematic end-of-disc data track CDRs).

Punch vs. CDR, the fight continues.

So nothing was playing reliably despite what I posted (I found out later...), my buddy chop5 told me to set laser pot to 0.8 (I don't remember what's the ohm rating for it so I don't know the scale), and now it seems that I can play all my retail games OK, but discs are still finicky.

I'll explain: I made a CDR with Beethoven's 9th Symphony, 4 tracks plus this one here: https://soundcloud.com/twinbros/ti-amo-japanese-coverversion (yes it's supposed to stand out from the classic music plus I like it, so what). 5 tracks total, 71'29''
1 - 16'24'' - 1956 Beethoven 9th concert 1
2 - 14'48'' - 1956 Beethoven 9th concert 2
3 - 13'55'' - 1956 Beethoven 9th concert 3
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)

When playing the CDR, it gets to the audio player quick, no issues, and it plays both 1st and second tracks fine. Fast forward was 'slipping' and landing like 30 seconds forward instead of the steps of one sometimes but I fixed that. Now for the problems...
Track 3 doesn't start when requested half the time, and when it does the audio is noisy (aka low quality signal, so much for being digital huh Compact Disc), Tracks 4 and 5 don't start at all and the poor laser keeps trying to reach it to no avail.
edit: I left the duo playing while I wrote this post and indeed, Track 2 also gets noisy when approaching the end (aka the beggining of disc 3).

Conclusion, and also a bookmark for your tl;dr people: I guess now the only thing I can do is procure better cds. As I said before I'm using generic 80 minute discs, and I don't have my 650 silver mitsuis anymore so I can't test it again (it's a long story). If someone had any luck with CDRs on your US Duo please post here, because I can only find people that got pissed off and just moved on to an RX or SCDROM2 or people that are "meh I don't play CDRs on mine". I thought that the Duo laser was/is a very popular laser? How come it doesn't like CDRs?

I'll source for more types of cds and I'll post my findings here later, but I think I did what I could adjustment wise.

Quote5 tracks total, 71'29''
...
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)
...
 Tracks 4 and 5 don't start at all

Probably not. The cd player was only designed for 60 min cds.
Track 5 is definitely out of range, and track 4 would have an end point out of range (making it an invalid track)

Very interesting, thanks TheOldMan. Guess I need to find a better way of testing discs. Do you know if there's any limitations in the CD BIOS search and play routines or is it something from the audio player program itself? Can't find anything on Hu7 documentation about max length.


edit: if you mean the disc drive itself was meant only for 60 mins max, that explains a lot. But I thought 74 min was the max. playback/storage time :/

Quote from: TheOldMan on 07/09/2016, 04:37 AM

Quote5 tracks total, 71'29''
...
4 - 22'56'' - 1956 Beethoven 9th concert 4
5 - 03'24'' - Ti Amo (Be-2)
...
 Tracks 4 and 5 don't start at all

Probably not. The cd player was only designed for 60 min cds.
Track 5 is definitely out of range, and track 4 would have an end point out of range (making it an invalid track)

Good eyes old man! ;) I wouldn't have caught that.

QuoteDo you know if there's any limitations in the CD BIOS search and play routines or is it something from the audio player program itself?

I haven't yet seen any limits in the bios on track lengths or position. But that's not where I would expect it anyway.
The cd system works by sending command packets to the scsi controller. Play is actually sent as 'seek to position ' and 'play to position' (from current). One of the things the routines have to deal with is a 'bad parameter' value - which is detected by the controller.

Basically, what that means is the scsi controller itself probably checks the locations, and returns an error if its out of range.

Quoteif you mean the disc drive itself was meant only for 60 mins max, that explains a lot. But I thought 74 min was the max. playback/storage time :/

Yes, the drive/controller can only reliably use 60 min / 650 M cds. Technology marches on.
I suspect that the controller limits were set higher then 60 min to allow for 'new' technologies on the near horizon, or for larger, in-print cds.

I remember something about the developers wanting all of a bach piece on 1 cd, so thats how they set the initial size. I also remember when 70 min cds came out, and being disappointed they wouldn't work in my 2x burner :(

I suspect that's also part of why some discs cause the laser to stick. The seek doesn't return an error (because the limits are larger than they needed to be, for the future), but the drive mech can't handle it.

That's a good explanation for the stick laser problem.

I think I calibrated my Duo the best I could this time, and guess what, I'm able to play the full 72 min. audio from the CD I was using. The problem is when seeking later tracks (again). When playing from beggining to end it has no trouble.
Something very curious happens, in fact... Fast forward is very fast on the Edge of the disc (like if the CD laser was reading 300% better!). I feel like the problem lies with the "coarse" seek since mechanically when it tries to coarse seek a track, it overshoots a little bit then self corretct going backwards. It seems that it has no room for error in the Edge tracks so it ends up getting stuck.

My next purchase will be an oscilloscope or a Duo-RX. :lol:

If it's too fast at the end or at the inner tracks try adjusting V101 slightly. The trick is to get a happy medium to where both the inner and outer areas can fast forward at about the same speed.

Hello Guys, got the following Problems:

Got a broken PC Engine Duo and i switched all caps and one Vram (had some graphic issues, one via was broken but i fixd it).
Now i got a new Hop M3 Laser and now the test:
It only reads Music CDs (No game cds)
I try to fix it with the pots but not really anything happen.
Is this a Laser adjustment Problem (with Pots) or another Proplem ?

The laser is probably out of focus. I would "put back" the pots to as close as stock and start with VR102, moving 1/16-1/8 of a turn each time until the CD's start booting. Use an ocilloscope if you have one and check the readings on the pots with a meter.

Did you change the caps that were under (below) the plastic hold-down for the CD player wires?

Dear blueraven,

i adjust every pot with my ears except VR102.(dont have an ocilloscope)
Then i start with VR102 (just a little bit up) and the game cd are booting.
I testest 3 games and every game is playing now. From one Level to another level it take some time to load (maybe i need a finetune) but it works now .

Thank you blueraven :)

if it plays cd audio perfect, its most likely bad cd work ram (the ram chip near the controller port)
any dead traces/vias around that ram would also do it

Quote from: blueraven on 11/20/2010, 08:12 PMAdjusting the Pots:

Advanced Users/Modders only! (unless you really want to risk it...)

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

Does this apply to the CDROM2 as well? Or are the pots labeled differently? My unit plays retail games fine, but I'm trying to get a demo level from a game I supported on Kickstarter to work. The CD-R works with MagicEngine, but not on my hardware. Thanks.

Quote from: tomiii on 11/16/2016, 02:02 AMDear blueraven,

i adjust every pot with my ears except VR102.(dont have an ocilloscope)
Then i start with VR102 (just a little bit up) and the game cd are booting.
I testest 3 games and every game is playing now. From one Level to another level it take some time to load (maybe i need a finetune) but it works now .

Thank you blueraven :)

Glad you got it working! You're welcome, Cheers! :D

Quote from: cueball1897 on 12/27/2016, 10:58 PM

Quote from: blueraven on 11/20/2010, 08:12 PMAdjusting the Pots:

Advanced Users/Modders only! (unless you really want to risk it...)

BEFORE YOU TOUCH ANY POTS, USE A THIN PERMANENT MARKER TO MARK EACH POT'S ORIENTATION.

Does this apply to the CDROM2 as well? Or are the pots labeled differently? My unit plays retail games fine, but I'm trying to get a demo level from a game I supported on Kickstarter to work. The CD-R works with MagicEngine, but not on my hardware. Thanks.

BlueBMW has pointed out that the SuperCD Rom2 is so similar to the Duo that having a duplicate post would be redundant. The CDROM2, (white/black) however is completely different internally, and would take some fine tuning to get a bootleg or burn or demo working. I've personally tuned a few of them but it was so long ago I don't remember which pot to turn.

the CDR2 is actually still the same chipset, and tunes much the same (with good laser)

Quote from: blueraven on 01/04/2017, 02:52 AMwould take some fine tuning to get a bootleg or burn or demo working. I've personally tuned a few of them but it was so long ago I don't remember which pot to turn.

That's good to know, I wasn't aware that the CDROM2 needed adjusting before it would read CD-Rs. I knew the media made a difference, but I was under the impression that they were just supposed to work.

Hi all,

I'm working on my pc engine duo this one has had some work done,
replaced all caps, ic502, cpu, cover switch, vr105....
After all said an done right now it loads card with no issues, cd's wont work.

I have got it where the disc spins, but after adjusting for about an hr the best i get is set disc, the worst I get is the disc don't spin..

I have a tektronix 2236 scope with a built in counter, the lowest the clock seems to hit is 4.4467 and then it goes back to the top..

Also the wave form tutorial is a little confusing. 
Pull the RF signal from pin 2 on the P5 connector, and ground it on pin 1 of P5.
so If i connect pin 2 to pin 1 the disc does not spin,but if i just put my probe on pin 2 and hit start I get a signal but it is super weak! approximately .25v pk-pk.

At this point I am thinking about buying a new laser, but at $20 I was hoping for some input first.

Thanks guys!

.25V is too low
adjusting the focus and tracking pots will change the Vpp, so try that first (target is between .7Vpp and 1Vpp)
the pot on the laser will directly effect it, but too high and the laser fails (shouldnt need to touch it)

 Thanks for the reply thesteve,

That's what I assumed but was not 100% sure, as such adjusting vr102 and 103 did nothing really, it would increase the voltage but it was still maxing out at .25 any change would decrease the voltage.

I did break down and bought a new laser, it should be here today but that low voltage has me worried that it wont do anything to fix the situation.

Update,
That did it replacing the laser made it work with no issue. just did some adjustments after and bam loading perfect!
Thanks for the tutorial and help!

Hi there, I hope I don't break any rules reviving this post... :oops:

I recently adquired a PCE Duo with CD reading error; I've already cleaned the board thoroughly and changed all caps, also made sure (to my really limited knowledge) that they all work well, no lifted pads or broken traces, but cd doesn't even want to spin.
I've read that the first step before adjusting pots is marking the "initial" point to be able to go back to safe settings, but the thing is that the former owner of the console told me that he "adjusted" them already.

A forum member kindly told me that TheSteve and Turbokon made a couple videos showing how to adjust them using an oscilloscope, but I haven't been able to find them, and the thing is that I don't have the knowledge to start fiddling with an oscilloscope without a proper tutorial or guidance...

What should I do?

Thanks a lot for your help.  =D> =D> =D>

Quote from: Cordelay on 05/01/2018, 03:41 PMI recently acquired a PCE Duo with CD reading error; I've already cleaned the board thoroughly and changed all caps, also made sure (to my really limited knowledge) that they all work well, no lifted pads or broken traces, but cd doesn't even want to spin.
I've read that the first step before adjusting pots is marking the "initial" point to be able to go back to safe settings, but the thing is that the former owner of the console told me that he "adjusted" them already.

A forum member kindly told me that TheSteve and Turbokon made a couple videos showing how to adjust them using an oscilloscope, but I haven't been able to find them, and the thing is that I don't have the knowledge to start fiddling with an oscilloscope without a proper tutorial or guidance...

What should I do?

Thanks a lot for your help.  =D> =D> =D>

OK, I slapped some screencaps together, and the comment section of Steve's video has even more information to tune those 3 CD potentiometers like a pro, although it's "rough" so I'll try to make sense of what you must do.

** Proper CD waveform when tuning a CD laser/player **

https://www.facebook.com/steven.hanely/videos/10201717056086907/

https://i.postimg.cc/cHQvBRjB/3-Pot-PCECDOscilloscope-01.png
https://i.postimg.cc/Bb4XY8f9/3-Pot-PCECDOscilloscope-02.png
https://i.postimg.cc/pX0pCX04/3-Pot-PCECDOscilloscope-03.png
https://i.postimg.cc/9Qrzn5KM/3-Pot-PCECDOscilloscope-04.png
(?action=dlattach&topic=8926&attach=6170&image) (?action=dlattach&topic=8926&attach=6172&image)
(?action=dlattach&topic=8926&attach=6174&image) (?action=dlattach&topic=8926&attach=6176&image)


* You hook the oscilloscope to P5 pins 1 and 2 (1 is ground, 2 is RF signal).

* Pots VR101, VR102, VR103, VR104 each effect the signal differently

* Once you play with it for a min, you should get a feel for it.

* The signal is comprised of a sign wave with a fixed slope and varied amplitude.

* So when the pulse is taller the frequency is lower, the peak/frequency variances are in fixed steps causing a grid effect.

* Your adjustment goal is max amplitude with minimal line jitter.

* VR105 is your sync hold pot.

---

Anyway, best I can do at this time, it's a real tough job to translate "steve-speak" for the common man (But I try on rare occasion like this YPbPr Component Guide we worked on together (https://www.pcengine-fx.com/forums/index.php?topic=13231.0)).

So, in a nutshell, you must get the CD waveform to look like [this] (https://www.pcengine-fx.com/forums/index.php?action=dlattach&topic=8926&attach=6172&image) what it does towards the end of his video while adjusting the pots. Since you say a new laser was installed and the installer adjusted those 3 pots away from factory defaults, it definitely needs to be done right, and this may help you if you solve the spinning problem first.

Personally, I think using a slow-burned CD-R of a game may/might be a smart strategy, you get it fine-tuned with a CD-R and they'll all work which should -- in theory -- guarantee that the laser works with original factory-pressed silvers. Although you may need to test that in practice.

On the other hand, if you only have originals, don't play burned CD-Rs for fan translations or downloads, then maybe don't bother on such an idea - stick with an original factory-pressed CD for tuning.

Good luck!

Oh man! Thanks a lot! I'll check it out when I come home from work, but this looks super detailed and useful.

What scope did you end up getting? I've seen a cheap 2channel 2MHz standalone.


Thanks a lot for taking the time to gather all the info.

Quote from: Cordelay on 05/03/2018, 09:09 AMWhat scope did you end up getting? I've seen a cheap 2channel 2MHz standalone.

Thanks a lot for taking the time to gather all the info.

Me ? I own the SainSmart DDS-140 USB Digital 40 Mhz Oscilloscope, bought it many years ago on eBay for $80-$90 USD. Together with a 7" Windows tablet for another $30 USD ('Twas a "Black Friday deal" via a local brick'n'mortar retailer), it becomes a full portable oscilloscope. The interface software was developed in MSVC++ for Microsoft Windows, so yeah, you need a Windows PC, tablet or laptop, etc. to use it.

sainsmart.com/.../dds140-pc-based-usb-oscilloscope-40mhz
DDS-140-Digital-Oscilloscope.jpg (https://www.sainsmart.com/collections/tools-instruments/products/dds140-pc-based-usb-oscilloscope-40mhz-bandwidth-200ms-s-black)

QuoteThanks a lot for taking the time to gather all the info.

Sure! But didn't you say the CD doesn't even spin ? You got other problems to deal with before even thinking about this I think ??

Quote from: NightWolve on 05/05/2018, 10:27 PMSure! But didn't you say the CD doesn't even spin ? You got other problems to deal with before even thinking about this I think ??

Yup, it wasn't spinning at first, but it was troubling me and had spare time on the weekend so I decided to give the first page tutorial a go.

As a starting point I used the xls file where a forum user wrote his ohms readings on the pots of a working Turbo Duo, and then I started tweaking using BlueRaven's and BlueBMW indications on the first page of this post. I got it working to the point that some original music cd's worked (minus some slow loading and a bit of trouble reading con the outer tracks) and the five or six burned games I tried worked alright. I knew it wasn't a permanent fix, but I was able to play games.  :dance:

But yesterday I tried to hook up a small 2MHz portable oscilloscope to try adjusting the pots using your tutorial indications and couldn't get a proper waveform so I assembled again the console and called it quits. I don't know what I touched, but the thing is that now it has problems reading CD's again, so I guess I'll reset the pots to the starting point and and try to get it at least reading burned CD's.

I think the moral of the story is: "You need proper tools and knowledge to do a good job" or also "If it's working don't fix it!"  :lol:

Here are some pics during the process:

TurboDuo.jpg
_{4K: https://i.imgur.com/Pxy6LMx.jpg}

TurboDuoYs.jpg
_{4K: https://i.imgur.com/gK9LDWD.jpg}

this is really good stuff.  I might have to consider an oscilloscope.  I've seen Ben Heck use one to great effect, but it was always a bit mystifying to me, I'll have to watch a tutorial and see if I can work out what's going on (the sheer amount of buttons and dials is a little overwhelming)

Ok, I've reset all pots back to "average" values, also tweaked a little bit the white laser pot (counterclockwise an 8th of a spin) and the screeching noises have disappeared and works again, music cds read super fast, but burned cds take a little more time.
I think the laser pot might have been adjusted too strong (due to failing caps) and with the new caps maybe it needed to be set back a bit...
As long as it loads games it's fine by me...

Quote from: soop on 05/08/2018, 09:03 AMthis is really good stuff.  I might have to consider an oscilloscope.  I've seen Ben Heck use one to great effect, but it was always a bit mystifying to me, I'll have to watch a tutorial and see if I can work out what's going on (the sheer amount of buttons and dials is a little overwhelming)

I've been watching reviews of the Hantek DSO5000 series and they seem to be a nice value for the money, but I find it difficult to justify forking down 250€ for something I still don't know either how to use or what to use it for... Just a couple months to my bday, so I might get one anyway :lol:

Quote from: Cordelay on 05/08/2018, 09:35 AM

Quote from: soop on 05/08/2018, 09:03 AMthis is really good stuff.  I might have to consider an oscilloscope.  I've seen Ben Heck use one to great effect, but it was always a bit mystifying to me, I'll have to watch a tutorial and see if I can work out what's going on (the sheer amount of buttons and dials is a little overwhelming)

I've been watching reviews of the Hantek DSO5000 series and they seem to be a nice value for the money, but I find it difficult to justify forking down 250€ for something I still don't know either how to use or what to use it for... Just a couple months to my bday, so I might get one anyway :lol:

Yeah that seems too much.  Check ebay for a second hand one, I just looked and there are some old ones going for like £30

Hi.
I know this post is very old, but I begin to Lost my mind and I think you are my last chance.

I bought long time ago a Duo Whitout caps and with caps new to install.

Board was really bad, a lot of pads missing, no volume control, no switch of CD cover open and close...
With a lot of time and patience I have get to star system card 3, repair volume and start games en hucards.
My final problema is CDs doesn't spin...I have try to configure all pots and I have revised all caps several times but always the same result:
-lens comes to the center
-lens go up and down 3 or 4 times.
-message of "revise CD"...
CD never spin.
I am desperate, long time spends and I begin to think I cant repair...
Someone can give some advice?
If I watch lens, I can see the red light of laser without CD.
Motor works, if I connect 3V to the motor, motor spins.
Thanks a lot.

Quote from: mouth78 on 03/12/2024, 05:13 PMCD never spin.
I am desperate, long time spends and I begin to think I cant repair...
Someone can give some advice?
If I watch lens, I can see the red light of laser without CD.
Motor works, if I connect 3V to the motor, motor spins.
Thanks a lot.

Hola m78, sorry to hear. So, one of the last active NEC console repair guys is @Keith Courage (Chris Brown). If you click his profile link you can PM (assuming he didn't turn off email notify) or reach him on Facebook where he's most active/available. I'll go ahead and inline his contact info, try:
1) https://www.facebook.com/chrisrocknrollbrown
2) chriscomputers @ hotmail.com

Since you're in Spain, I don't know anybody in Europe who you could cheaply ship it to for repairs. I know Jodi in Canada, or Chris in US/Indiana, and a few handful of others on Twitter that are US or Canada based, so shipping would be terrible. Sorry.

Also, if you do register on Facebook, try asking @thesteve:
3) https://www.facebook.com/steven.hanely

If you still think you can fix it yourself, he may be able to guide you, give you the right tips. But given your language barrier and his sparse communication style, it'll be tough.

Quote from: mouth78 on 03/12/2024, 05:13 PMHi.
I know this post is very old, but I begin to Lost my mind and I think you are my last chance.

I bought long time ago a Duo Whitout caps and with caps new to install.

Board was really bad, a lot of pads missing, no volume control, no switch of CD cover open and close...
With a lot of time and patience I have get to star system card 3, repair volume and start games en hucards.
My final problema is CDs doesn't spin...I have try to configure all pots and I have revised all caps several times but always the same result:
-lens comes to the center
-lens go up and down 3 or 4 times.
-message of "revise CD"...
CD never spin.
I am desperate, long time spends and I begin to think I cant repair...
Someone can give some advice?
If I watch lens, I can see the red light of laser without CD.
Motor works, if I connect 3V to the motor, motor spins.
Thanks a lot.

Quote from: NightWolve on 03/12/2024, 06:28 PMSince you're in Spain, [...]

If you still think you can fix it yourself, he may be able to guide you, give you the right tips. But given your language barrier and his sparse communication style, it'll be tough.

Hi there! I'm from Spain too :P I never checked a Duo per-se but I have my hobbyist electronics workshop where I (try to) fix consoles and everything that falls into my hands, so depending of your location you can come or send it to me if you're willing to do so.