REPAIR GUIDE - PCE|TurboDuo/R/RX: CD Laser Swap & Adjustment Guide

[blueraven]

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):


_{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
power-tool-accessories/drill-bits/2629392
product_image/27SBT10.jpg

_{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.


_{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.


_{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.


_{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.


_{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).   


_{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.


_{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
electronix.com/cd-pickup-hopm3-p-14472.html - No longer in business/stock, try eBay!
Model: HOP-M3, Cost: $18.95



_{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.


_{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.

[blueraven]

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

These 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.

my 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



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

Addendum:  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.   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!

[Opethian]

legendary thread! thanks bleu
CAW!

[Duo_R]

Nice work! Please sticky this thread!

[BlueBMW]

Excellent guide bluebird!   

[Duo_R]

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

Again this is epic!

[blueraven]

legendary thread! thanks bleu
CAW!

Nice work! Please sticky this thread!

Excellent guide bluebird!   

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

So 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.

Again this is epic!

Thank You again, Duo_R!

[Duo_R]

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



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.



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. 

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

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.

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.

[Duo_R]

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.

[BlueBMW]

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

[Charlie]

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

[chany60126]

It took one long night, but I was successfully able to replace the laser on my duo! 
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. 

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. 

[blueraven]

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

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!

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

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

It took one long night, but I was successfully able to replace the laser on my duo! 

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 Enjoy Your Duo!

[chop5]

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

[Platinumfungi]

Another invaluable resource to the NEC community! Great job 

[bartre]

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

[blueraven]

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

can i get it off electronix so i can save on shipping?

I've only bought lasers from them.

[incrediblehark]

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...

[BlueBMW]

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

[incrediblehark]

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.

[BlueBMW]

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.

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

[thesteve]

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

[Charlie]

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

[Keith Courage]

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.

[thesteve]

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

[raylyd]

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  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.

[BlueBMW]

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.

[thesteve]

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

[geise]

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!    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.

[bust3dstr8]

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.

[geise]

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

[thesteve]

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

[geise]

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

[thesteve]

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

[geise]

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

[Keith Courage]

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.

[thesteve]

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

[Keith Courage]

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.

[thesteve]

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

[Keith Courage]

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.

[thesteve]

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)

[whitecatangel]

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

[whitecatangel]

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

[mikebrandt]

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

[thesteve]

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.

[OldMan]

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

[mikebrandt]

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?

[whitecatangel]

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)

[mikebrandt]

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 

Mike

[whitecatangel]

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