[SOLVED] PC Engine Duo - No disc spin: not pots and new laser?

[beepinghazel]

Hi, first post here. I recently purchased a PC Engine Duo that would "not play disc games". The system itself works fine via composite out and there's audio through the headphone jack. The laser would not move on the rails or make any noise. I owned a TurboGrafx-16 as a kid and always thought the Duo systems were really cool.

I did a full cap replacement and replaced the laser with a new HOP-M3 unit. Once that was done, I tested with a legit copy of JP Valis IV and a retail audio CD from the 90s. Neither of the discs appeared to be recognized ("Please set disc") but the laser unit would jiggle a bit after hitting Run. The rails are lubricated using some of the excess from the old HOP-M3. The motor that moves the laser along the rails works properly - it spins indefinitely if I remove the gear that actually moves the laser towards the "stop" switch.

I then cleaned the pots with electrical contact cleaner. With the power off, I then measured VR102 and VR104 with my measuring tool and I could get values of 1-10k Ohm on VR102 and then 1-20k Ohm on VR104, respectively. I do see voltage going into the CD unit with the main power turned on (after hitting Run); 3v, 3v, 10v, 10v from left to right.

I tried adjusting the pots using the guides on the site (mainly VR102 and VR104), but neither caused the CD to spin. From what I understand, the CD will not spin until the laser has focused on the CD (please correct me if this is incorrect). I tried adjusting a few degrees at a time on VR102, hit Run, waited, reset the unit via Start-Run, rinse, repeat. I then reset VR102 to 1k Ohm and tried with VR104. No change, still get the "Please set disc" and the CD does not spin. I don't have the magnetic "cap" from the lid in place, I'm not sure if that makes a difference?

When the laser unit jiggles a bit left-to-right, I don't hear the laser attempting to focus or move up/down vertically like on a PlayStation 1 - I assume this is because it's all done by hand via the VR10x pots? The only thing I hear is the initial jiggle. The unit does reset itself to it's initial state (far left) if I move it down the rails away from the small "stop" switch. The same thing happens when I swap out for the old HOP-M3 unit. Continuity seems good between the board and the HOP-M3 connections.

Any suggestions as to how to proceed from here, or what to test to confirm everything is operating normally?

Random aside: I've seen references to IC105, IC106 and IC501 failures.

Thanks for your help!

edit: One thing to note - At no time do I see a reddish light coming from the laser lens itself. The laser lens always appears to be clear. I've checked visually and using my phone camera (in case there was a refresh rate/low light level that my eye couldn't detect).

edit 2: I found a post mentioning that the laser unit should be trying to focus on the CD. My unit doesn't ever try to focus on the CD (moving the laser lens vertically up-and-down). It just wiggles left-and-right quickly on the rails and stops. I also don't see any light coming from the laser at all. This suggests to me that maybe one of the ICs is bad? Is there any way to test IC105, IC106 and IC501 with a multimeter? I don't have an oscilloscope, unfortunately.

edit3: I do see 5v on pin1 of IC501. Not sure if that means anything. I've gone through and cleaned any corrosion, including underneath the card slot.

EDIT 4: 12/01 update; The system works perfectly after fixing R199 and replacing the two BA6290. Prior to replacing these, the system was washed in soap/water. I also applied lithium grease to the CD lens rails. The system now runs stable and really well. I ended up 3D printing a replacement HuCard door since mine was missing.

[thesteve]

ok it sounds like everything is coming up except the laser and RF amp, but lets make sure
lid up press run (should say to close cover)
lid down press run (light on, laser on, laser moves to switch and back off switch)
open lid when light on (light goes off) close lid
press run again without resetting (same as first time)
that confirms most of the servo communications
go through the whole process noting anything that doesnt follow and post results

[beepinghazel]

• lid up press run (should say to close cover) - OK
• lid down press run (light on, laser on, laser moves to switch and back off switch) - NOT OK. Red LED OK, laser moves to switch and back off OK. BAD: No laser light from lens and it does not attempt to focus (vertical up/down).
• open lid when light on (light goes off) close lid: OK. Red LED turns on, but turns off when the lid button is open.
• press run again without resetting (same as first time): OK. "Please Close Cover".

[beepinghazel]

Off the CXD1167Q

with multimeter:
5v on pin 33, pin 73

with logic probe:

pin13 - Nothing until hit RUN, then data (H/L pulsing), then stays high with low pulses. Reset to nothing when system is reset via Run-Select.

pin14 - always high, then pulses of low when you hit run

pin15 - nothing, then with you hit RUN, high/low pulses, then stays low

[beepinghazel]

I'm still really confused as to why the HOP-M3 doesn't light up with a laser light and why the lens doesn't move up and down to try to focus.

Last night tested these for continuity on IC501 (with my multimeter) and they all look OK.

94   RST
95   GND
96   IC105 PIN46   [SCSI DATA
97   IC105 PIN45   [SCSI DATA
98   IC105 PIN44   [SCSI DATA
99   IC105 PIN43   [SCSI DATA
100   IC105 PIN42   [SCSI DATA
101   IC105 PIN41   [SCSI DATA
102   IC105 PIN39   [SCSI DATA
103   IC105 PIN38   [SCSI DATA
104   NC
105   -> IC103 PIN21
106   <- IC103 RESISTOR PIN22
107   IC105 PIN86   CD DATA (SERIAL)
108   IC105 PIN88
109   IC103 RESISTOR PIN69
110   IC103 PIN24 + IC104 PIN20
111   IC103 RESISTOR PIN77
112   GND
113   IC104 PIN19
114   IC105 RESISTOR PIN57
115   IC105 RESISTOR PIN33
116   IC105 RESISTOR PIN55
117   IC105 RESISTOR PIN35+54
118   IC105 RESISTOR PIN32
119   IC105 RESISTOR PIN56
120   GND

[thesteve]

We kinda established that 105 to 501 was good
The RF amp CXA1081 controls the laser and sets the focus status (check around it)

[beepinghazel]

Thank you so much for your help so far. This has been a great learning experience and I would really love to get this thing working.

Edit: did some testing around the CXA1082 by mistake, didn't realize CXA1081 was under the board.

[beepinghazel]

From my multimeter:

2.5V each on pin 10 & 14, 5v on pin 30 of CXA1081
Continuity on the CXA1081 pins to the board trace holes look OK.

Reading from the CXA1081 (on the bottom of the board) using my logic probe connected to 5v:

pin 1-4, nothing
pin 5 is high, no change on RUN
pin 6 low, no change on RUN
7-15, nothing, no change on RUN
pin 16 high, no change on RUN
pin 17 low, no change on RUN
pin 18 high, no change on RUN
pin 19 high, no change on RUN
pin 20 nothing
pin 21 low, no change on RUN
pin 22 low, high pulse on run, then high pulse on "Please Set Disc"
pin 23, 24 nothing
pin 25 low, no change on RUN
pin 26 nothing
pin 27 H/L (no pulsing, just H/L on my logic probe)
pin 28 low, no change on RUN
pin 29 nothing
pin 30 high, no change on RUN

[thesteve]

Pin29 is your issue
It should be getting a signal to turn on the laser

[beepinghazel]

That was it, I have a laser now! (But no focusing by the lens.)

R199 (4.7k) had some serious corrosion under it. It didn't have continuity between it and it's test points. So much in fact, that as soon as I started soldering the resistor off to clean it the pads came right off with it. I've got things wired up now with a temporary resistor and the laser light comes on properly.

R199 sits between pin 29 on the CXA1081 and pin 63 of D78C14GF (IC104).

I don't see/hear the laser trying to focus vertically up/down like I think it's supposed to.

Thanks so much! Where to go from here?

Edit: going to guess CXA1082 (IC102) Pin 5 (focus drive output) - this pin does three long H before the system generates an error. It's trying to focus the lens?

Edit 2: The three long High long pulses from CXA1082 (IC102) Pin 5 make it to one end of R133 (1002 marking, 10kΩ) but I don't see the pulses on the other side of the resistor. The other side of R133 just sits H, no change on RUN (at 7v). The 1002-marked resistors all measure in the 8.5-9.5kΩ range when measured on the board. https://i.imgur.com/ENpbqaq.jpg

Edit 3: Following (but not connected to?) R133, I end up at Pin 9 of the top-of-board BA6290A (IC109), and I'm measuring 7V there. When I hit RUN, I see the voltage drop to ~6V and spike three times slowly to ~7.5V. I couldn't figure out how to trace this to a pin that leads to the HOP-M3. I also couldn't use my logic probe because I don't know where to get 7V from the mainboard. Should this be 5V? See Edit 4, which may explain why things look weird here.

Edit 4: The components under the (bottom of board) BA6290A chip - R294, C294, R293, C293 appear to be missing? Can anyone confirm whether these should be present and what values they should be?  https://i.imgur.com/rB537pM.jpg

[thesteve]

Those missing are normal
The BA6290 is a current input chip, so you won't really see a voltage shift on its inputs
It's outputs go directly to the laser

[beepinghazel]

Should I be looking around CXA1082 (IC102) for anything that could interfere with the laser lens not focusing up/down? Or somewhere else? I checked a number of traces but didn't find anything obvious (I'm hunting blind).

Do you know what pins/chips are responsible for the laser lens moving up/down vertically?

Thank you again so much for your help.

[beepinghazel]

Decided to test a few things.

Using Elenco LP900 Logic probe (forgot to mention that previously).

Unless specified, assume no change on logic probe and no voltage change on multimeter (when the RUN button is hit).

ba6290A bottom of board
pin1 11.1v ("Vcc") H
pin2 5.6v H
pin3 5.6v H
pin4 5.6v H
pin5 5.6v H
pin6 5.6v H
pin7 L, "mute" (per spec sheet)
pin8 5.6v H
pin9 5.6v H
pin10 5.6v H
pin11 5.6v H
pin12 GND, L

Short pin5 and R147 (by accident.. heh), and it spins the CD and moves the head.

ba6290a top of board

pin1 11.1v ("Vcc") H
pin2 10.1v H
pin3 10.1v H
pin4 10.1v H
pin5 7.1V, drops to 6.6V three times when hit RUN. H no change on probe.
pin6 5.6v H
pin7 No signal from probe, "mute" (per spec sheet)
pin8 4.6v H
pin9 2.6v No signal from probe
pin10 2.6v No signal from probe
pin11 2.6v No signal from probe
pin12 GND, L

black CD drive head left-to-right motor connector (pin 1-7, L to R)
pin1 5.6v H
pin2 5.6v H
pin3 0v L
pin4 0v L, two pulses H resetting head
pin5 1.8v H, two pulses L resetting head
pin6 5.5v, H, two pulses L resetting head
pin7 5.6v H

white HOPM3 connector (pin 1-8, L to R)
pin1 2.5v
pin2 2.5v
pin3 5v H
pin4 2.5v
pin5 2.5v
pin6 2.5v
pin7 2.5v
pin8 2.5v

red HOPM3 connector (pin 1-8, L to R)
pin1 10v H
pin2 10v H
pin3 2.5v
pin4 2.5v
pin5 0v L
pin6 0v L
pin7 ~1v, jumps to 1.75v between head resets, then back to 0v
pin8 0v L

[beepinghazel]

A few interesting observations (which match the datasheet) -

When I apply my logic probe:
IC102 pin38 makes the cd spin
IC102 pin15 makes the head move right
IC102 pin29 makes the head not move at all

Three H pulses from IC102 pin5 lead to -> R133 (& adjacent side of R145)-> pin 5 of top-board ba6290a.

[beepinghazel]

Hope everyone (in the US) had a great Thanksgiving.

Just noticed L101. Does this look normal?

https://i.imgur.com/6X4W4bt.jpg

[beepinghazel]

Since last week:

Washed the board in soap/water with full dry, system still behaves as before. Laser lights up but no focus attempt by laser.

Replaced several questionable-looking SMT resistors. They all tested fine once removed from the system, replaced with new SMT resistors. No change. Laser still does not try to focus.

It appears that whoever owned this system before replaced several resistors that appeared to be damaged - the stock resistors are marked 103, the new ones are blue and marked 1002 (both 10k Ohm).

Sanity check: What should R295 be? Should it be a 390Ω resistor?

I re-checked the board with my multimeter continuity checker still cannot find a single broken trace or bad contact.

Those missing are normal
The BA6290 is a current input chip, so you won't really see a voltage shift on its inputs
It's outputs go directly to the laser

Any suggestions on where to look for signals that focus the laser vertically?

Or is there anyone with a working PCE Duo willing to post photos of their motherboards? I wonder if the person that tried to repair the board before me replaced a resistor incorrectly. Hell, I wish there were a parts manifest.. something.. anything.

I'm not certain where to track down the signal that focuses the laser unit. I see the pulses for it (see my previous posts) but I don't know the system well enough to track down where the breakdown is..

Thanks again for your help.

[thesteve]

try replacing the BA6290 on top of the board
the one by the plugs runs the 2 motors and the other runs focus and tracking directly on the lens

[leonk]

Silly question:

How does washing the board might make it work? I recently did a cap kit on a Duo (cleaned all the pads from old solde; it was cleaned with qtip and alcohol). Added fresh solder and tacked down new caps. Everything worked except for disc.

Ended shipping it to theSteve and he said all he did was wash the board and all is well now.

[MNKyDeth]

The electrolytic fluid from the caps is conductive.

If you done get it all gone from the boars,  traces and thru-hole locations that go from the top and bottom of the board it can create shorts.

Very hard to troubleshoot until a good wash has been done. Usually after removing everything from the motherboard is when to give the entire board a bath. But washing with new caps should be fine as well as the caps are sealed. The old ones most likely not anymore from the leaking etc.

[leonk]

good to know. So you soak it to warm soappy water, use a soft brush, rinse it again and let it dry. correct?

What about the super cap for memory backup? It's got voltage stored there!

[MNKyDeth]

I have never cleaned a board with caps on it. So I can't say if or what are any bad effects of doing this.

I don't have a dishwasher so I literally give my boards a rubbing alcohol bath. I then go over the entire surface top and bottom with q-tips and an old toothbrush.

Once that is done and the board is clean any thru hole location that had corrosion around it or is black I then make sure to pay attention and clean them all put and sometimes even put cap legs thru them and solder them in place.

Then I put the new op-amps,  7805's and caps back on the board. Then any mods people want. 

[leonk]

why would you replace the op-amp?

[beepinghazel]

@thesteve - thanks, I've got a couple on order. Will reply once I have them in.

[thesteve]

the caps go through the wash without issue, i pull them first if replacing just to get a better clean under

[MNKyDeth]

why would you replace the op-amp?

There is usually a lot of leakage around three of the op-amps. When I take them off to clean under them I usually just replace them. 4558 op-amps are rather cheap so to me it's usually a negligible cost.

[beepinghazel]

AMAZING NEWS!

I got a pair of BA6290 and replaced the ones on the board. I can now play an audio CD (sort of)! It's definitely having some trouble dialing in the later tracks (it switches to "disc change" after a bit). The first tracks come up pretty quick though.

Edit: The laser lens started trying to focus immediately after replacing the two BA6290, which it had never done before.

I tested my copy of Valis IV, but no luck with that (not surprised). Going to work on the pots next.

THANK YOU thesteve! Not quite working but definitely an improvement!

[beepinghazel]

So far so good! Got Valis IV to load properly. Working on the gamepad at the moment. These pot settings seem to work more or less "ok" with the new HOP-M3.

https://i.imgur.com/GHRGzyk.jpg

[thesteve]

Turn VR103 about 90' clockwise and you should get better results

[beepinghazel]

@thesteve 90' turn seemed to help. The CD player seems to spin more slowly and at a constant rate. I was even able to use a CDR without any issues.

There is a slight whining coming from what I think is the motor that spins the CD. You can hear it here, but it's very faint ( http://sendvid.com/lqee7hsk ). Is there any way to lubricate or even replace this motor? Does anyone know the part# for it?

I didn't re-lubricate the metal rails after replacing the HOP-M3. I've read that white lithium grease works well, but others have suggested molybdenum disulfide grease or teflon grease works. Any suggestions on what to use?

I'm trying to make any final maintenance changes to the base system before moving on to RGB and region-free mods. Any other suggestions are appreciated.

[Keith Courage]

Turn V104 slightly (clockwise) or turn V103 (counter clockwise) to remove whine.

[beepinghazel]

I lubricated the rails and cleaned the gears, and that really reset things (they must have been adding some resistance to read operations). Luckily I went back and got everything working again. It's down to a low hiss that's not really detectable against the background/ambient noise of the room.

https://i.imgur.com/bOKB7Sy.jpg (pots)

http://sendvid.com/3dlpl3rt (video)

So far so good.

edit: thanks Keith Courage for the VR104 tip. That got it quiet.

edit: Oddly enough, there's a slight tradeoff between it being quiet and load speeds during track changes. Is that my imagination? I prefer quiet to load speed.

[thesteve]

There is a trade off if you set it too quiet
It also makes it less vibration sensitive

[thesteve]

More not less

[sherpard]

Good morning,
I followed the work carefully.

I tested the voltages that occur on the moteus, optical block. Everything seems ok
I make a cap head kit.

When I press run on the screen tells me "just a moment" and nothing else happens
Red led does not light

I have the impression that there is a command does not arrive at a component

I found the values in OHM

Vr101 = 12.56 kohm
Vr102 = 968 ohm
Vr103 = 3.22 kohm
Vr104 = 4.66 kohm
Vr105 = 2.13 kohm

If you have an idea???

Thank you for your help

[beepinghazel]

When I press run on the screen tells me "just a moment" and nothing else happens

* Do you see a laser coming from the lens? (My R199 was bad)
 * Does it try to focus the laser (move up and down)? (One of my BA6290 chips was dead)

For me, each of those was a separate problem.

[sherpard]

Hey
I do not have a laser beam
I replaced 2 6290. nothing has changed
I also changed the lens. Nothing has changed

I measured the resistance that gives me 4.67k

Is it the right value?
What is the component that activates the cd?

[thesteve]

the LED not lighting is your first clue
odds are its also not reading the lid switch
look for a missing signal to IC501

[sherpard]

the LED not lighting is your first clue
odds are its also not reading the lid switch
look for a missing signal to IC501

I can not find the datasheet for ic501 (NEC D91317GD)

Have you ??

What pine I have to do the test ????

Thank you for your help

[thesteve]

search it on this forum, i posted a pin list