Please close cover! Audio issues!

[pdiggitydogg]

Been a long time...
I decided to try my hand at repairing a Duo and have replaced all capacitors but, even after shorting the lid switch, the console keeps telling me "Please close cover!"
Does anyone have values for the diode at D102? I'm reading 660+ohms between the two lower points and the common, which leads to the microcontroller ic.
The switch itself is good, for what it's worth...but I've still jumped the two pads next to it for testing.


Edit*
Audio somewhat restored by removing the diode at D306, which reads less than 1v on right pad near large trace and 5v on left pad, near R315

[pdiggitydogg]

I should say that the hucard slot works fine. I'm waiting for some new op amps but composite video is ok.
When I initially power it on the laser eye moves horizontally, but doesn't try focusing vertically. It does not move the sled. I applied voltage to the motor and sled, individually, and both seem to move freely.

Reflowed ic104
Ordered up a logic probe...

[pdiggitydogg]

Im working on a no audio issue as well - replaced the op amps today, at IC506 and IC507. I did not get anything and noticed the voltage was 0.91v.
I followed this to D306 where I saw that same low voltage on the right lower leg and 5v on the lower left, nearest R315, and 3.9-4v at the top.
I removed the diode completely and I HAVE AUDIO (quiet and noisy, but still!)  I tested 5v on pin 1 of IC505, from the  7805, and it improves GREATLY and the headphone jack also works (did not before).
If I check voltage of the top pad the volume is cut considerably.
Low voltage persists at the right pad - and therefore the same .9v at the op amp pin 8.
Shouldnt this be higher voltage than 5v? More like 7v?

This looks to be the exactly the same diode that controls the CD cover door switch that is also giving me grief at D102. It looks to say P 41 on both.
D602 looks identical and I can make out P 41 more clearly. I would love to swap these out but P 41 doesn't seem enough to go by for replacement.

https://www.mouser.com/ProductDetail/Littelfuse/LSIC2SD120D10?qs=sGAEpiMZZMutXGli8Ay4kCGDIyhNvP0xCPPxVA6pmGo%3d
I found this, but I am really unsure if it is correct, as I dont have experience with diodes like this.

What is ZD302, near the pins for IC505 on the back side?? Shouldnt that read around 8v?

[pdiggitydogg]

Can anyone at all tell me where the voltage originates for the audio circuitry?
There's a large trace/rail on the back of the board that feeds voltage to the audio caps, ic505 and op amps, both near the av connector and all the way down and across to the CD side of the board. This is the line I fed 5v to and regained audio, in testing, but I want to fix this correctly and in the right place.
I have definitely over-looked something and cannot figure out the source capacitor or trace. Something really simple most likely.
I also do not know if it should be 5v or more, since I've read some people seeing over 7v at ic505 pin 1 but that would mean it probably comes directly off the large power filter caps and I can't see where that would come from either.

[NightWolve]

Keith Courage has been on a roll with the tech threads lately, you can fire a PM to him, if not thesteve (although I mainly see him active on Facebook). There was another smart tech guy active recently that might have some answers, his name escapes me, so I leave it to you using search to find his recent posts and asking him.

[pdiggitydogg]

I appreciate it. I re-recapped the audio section and the result is the same, so I am just missing it entirely. I'm just about ready to tap 5v from another rail and run it right to where I need it to be for audio.
I don't have facebook so its probably dead for thesteve. I read a ton of his posts recently.
The logic probe came today, so I'll start checking what I have against some threads that I found and hope that the other posted values of others are correct.

This place seems a lot slower than it was the last time I was here

[NightWolve]

https://www.pcengine-fx.com/forums/index.php?action=profile;u=3863

Le Steve stopped by on the 23th I see, you can reach him by PM too. Plus, he's the goto guy if you can never fix it. Everybody else in the PCE repair business send console hardware to him when they've given up.

[pdiggitydogg]

Keith suggested a possible smd regulator. I found this thread:
https://www.pcengine-fx.com/forums/index.php?topic=23041.0

All 4558:
Check that pin 4 has ground connection.
Check that pin 8 has power (≈7.3V)
Power for all 4558 IC506, IC507, IC503, IC521 (also IC203 CD part and IC202 CD part but 4560) gets its regulated power from Q304 (SMD Mark BR, located in the middle of the cap jungle beside the two main regulators) Japanese SOT-23 (SC-70) incoming ≈8.2V on pin 3, outgoing ≈7.3V on pin 2 and pin 1 should ≈8.0V, IC107 4558 (CD part).

This regulator IS only putting out .9v on the leg which is what I'm seeing on the rail. I feel pretty confident this is the issue for the audio. I'll source a couple and swap asap.
Then on to the CD issues.

[NightWolve]

Ah, Fidde-se made a full guide for this problem and not that long ago either. So a short somewhere causing the voltage drop or regulator has failed ?

[pdiggitydogg]

I can't find anything shorted, since I removed the reactors on av out.
Someone had tried reworking this board before me (also lovingly applied copper sheeting to the bottom of the case) so it may have happened then or it could have just died from the cap fluid leak(?)
I dealt with a bad voltage regulator on a Nomad once, but it was main power and I never did find out why it died. Replaced and no issues after.

Fidde-se's thread should be stickied, I think. The information on the traces, paths, part numbers, and readings looks invaluable for troubleshooting audio.

[Fidde_se]

Glad it gets used.

When a rail is low it's not always the regulator thats gone bad, it's often something that brings it down, very often (but unfortunatly not always) that leaves a heat trace, so you can find it with a thermal camera within seconds, poor mans version use cold/freezespray and spray it on the board, a thin layer of frosting will appear on the board and where its warm it will melt, thats where the component bringing down the rail is located.

[pdiggitydogg]

Looks like you are right. I removed Q304 and bench tested it - it seems ok with just a slight voltage drop on the leg that's giving me trouble. It looks like there is a lot more to this than I am finding on my own.
I'll reinstall the little guy and try an inverted air duster spray, since I dont own a thermal camera, to look for heat.

The battery in my meter just died, swapped it out, and I am seeing a some connection between ground and positive rails. Sheesh.

[pdiggitydogg]

Well. I've removed a lot of chips in my attempts to eliminate the issue.
From the back, I've pulled IC: 521, 504, and 503
From the front, I've pulled IC:505 and 502, 203, and 202, along with capacitors 305, 306, and 615 in the audio section.

On the back I also went to D306 again... I lifted the right leg.
Audio works. And it works great. I still, however, have low voltage across that rail from Q304.
AND the bios also reads "Just a moment"...but the CD drive is disconnected.
If I reconnect the drive without ground leads it still says that.
I connect ground leads and it tells me to close the cover again.
Remove the same grounds again...still close the cover.

NOPE. I DONT UNDERSTAND.

[Fidde_se]

I have mostly had the switch for closing cover gone bad so not looked closer on the circuitry behind that but the switch might lead to a circuit that is powered with one of the faulty rails and therefor not working correctly, so fix the rail might "fix" the cover....

[pdiggitydogg]

I think that is entirely possible. What I am afraid of is that it's caused by a bad IC, like 104/105.  I can logic probe these, but I am not sure if the tables I've seen here, from other problem posts, are ok to use as reference.
I think I need to take some time away from this. I spent 7 hours straight on it yesterday, just beating my head on the wall.

[pdiggitydogg]

Could someone please tell me the value of the resistor at R137? I am missing it.
It's on the back of the board in the CD section, near the unused white  connector, on the corner.

Edit* Seems like there isn't one there.
I'm going to run this board through the dishwasher. I pulled up three cermaic caps along the troubled rail and gained voltage, so that it comes up to ~3.5v instead of 0.9v. I'm hoping that a dishwasher cleaning and rinse with distilled water followed by 91% will clean off any residual electrolytic fluid, flux, or loose solder bridges that I have missed in the other soakings and manual brushings.
I have no idea what I'll do if it makes no difference. I guess freeze spray the board...

Eidt 2**
I should have figured my fingers had lost a lot of heat sensitivity. Passed my wrist by ic520 and it's way too hot. I removed it and get a white screen (bios fails to boot) but cards work. I have to look at the traces since I'm guessing it's working but maybe not properly.

 I'm just posting here as a blog of my adventure, at this point.

[thesteve]

IC520 is a high failure part that is used to switch between card and cd system
IC104 handles the cd system I/O for switches and track counter ect
the lid switch gets a pulse from IC104 and sends it back to IC104
D102 is a simple diode used as ESD protection for IC104 (lid switch passes through it)
cd bios calls cd system and says please wait, cd system responds with lid open or active..........lid open is shown if thats the response
please wait is shown until the cd drive responds

[thesteve]

ZD302 is an 8V zener diode used to feed Q304
D306 is part of the anti thump mute circuit

[pdiggitydogg]

Thank you for coming by Sir Steve!

I wanted a break from the low voltage rail to mess around with the CD side again, today.
I took measurements from the switch to IC104:
Switch to IC104 pin 32: 18.9k ohm
-------------------pin 33: 2.2k ohm
-------------------pin 34: 18.8k ohm
-------------------pin 35: 19k ohm

IC104 pin 8 to switch: 4.7k ohm

I also tested the logic of IC104, at the BIOS screen
1 H
2 L
3 L
4 H
5 NOTHING
6 H
7 H
8 L (lid switch open or closed)
9 H/L PULSE
10 H/L PULSE
11 H
12 L
13 NOTHING
14 H
15 NOTHING
16 L
17 NOTHING
18 L
19 H

20 L
21 H PULSE
22 H
23 L
24 L PULSE
25 L
26 L
27 L
28 NOTHING
29 NOTHING
30 NOTHING
31 NOTHING
32 L

33 L (open or closed)
34 L (open or closed)
35 L (open or closed)
36 H
37 H
38 H
39 H PULSE
40 H/L PULSE
41 H/L PULSE
42 H/L PULSE
43 H/L PULSE
44 H/L PULSE
45 H/L PULSE
46 H/L PULSE
47 L
48 L
49 H/L PULSE
50 H/L PULSE
51 H/L PULSE

52 H/L PULSE
53 H/L PULSE
54 H/L PULSE
55 H/L PULSE
56 H/L PULSE
57 H
58 H
59 L
60 L
61 L
62 L
63 H
64 H

Finally, I took some pot measurements at VR101-105. To be blunt, I am sure they need to be swapped.
I reinstalled IC520, for this - it still gets too hot. Which of these is correct? Will they all be ok to use?
https://www.mouser.com/ProductDetail/?qs=zhgwDAIOVxsHa0ucvb6uNw%3d%3d
https://www.mouser.com/ProductDetail/?qs=w32V8uFkMxmYRFvChjgYdA%3d%3d
https://www.mouser.com/ProductDetail/?qs=afYny40WCj2l4ve8LWqd9g%3d%3d

[NightWolve]

Thank you for coming by Sir Steve!

I was thinking of PM'ing him with all these tech support threads piling up, but he finally stopped by. Keith can't cover all of this by himself.

[pdiggitydogg]

I checked logic of IC520 this morning.

At the bios screen:
1 - 9: H/L Pulse
10: L
11-18: H/L Pulse
19: H Pulse
20: H/L Pulse

While running a HuCard:
1:H
2-9: H/L Pulse
10: L
11-18 H/L Pulse
19: H Pulse
20: H

[thesteve]

im not opening your links
for IC520 you can use the HC or LS series chips, doesnt matter to it
only thing to watch is you need the narrow version  otherwise install gets a bit tricky
also i dont think IC520 has failed
dont recall which pin gets the pulse from the lid switch, but start by probing the switch itself (should be pulse 1 side open, both sides closed)
either way trace it back to the chip, just if pulse confirmed you only need to trace the switched side

[pdiggitydogg]

I probed the switch today and, just as you said, I get signal on one side when its open and both when its closed.

I dont have a lot of time to play around with it today, but after I swap out the pots and put all the removed components back I feel like I'm just sending it off to thesteve.
Defeated.

[thesteve]

ok just fixed it
found Q304 failed open (very common sound issue)
switch had low on one side and floating on the other (not right)
found no pulse from IC104 (replacement solved switch issue)
laser was also bad (no light)
confirmed working with new laser

[NightWolve]

ok just fixed it
found Q304 failed open (very common sound issue)
switch had low on one side and floating on the other (not right)
found no pulse from IC104 (replacement solved switch issue)
laser was also bad (no light)
confirmed working with new laser

!!!Turbo Repair Titan!!!

@pdiggitydogg: Wow, so you did send it off and he already went to work on it! Had a lot of problems at once then, damn!

[pdiggitydogg]

Yep, it was beyond my ability. I did suspect ic104 was bad in the end, but I wasn't testing it correctly and wouldn't have been able to get another easily anyways.
I learned a TON trying to figure this out and actually really enjoyed it up until I knew I couldn't do it. Knowing when to get professional help is something I still struggle with, on any project.
Super glad it was able to get fixed up by thesteve. I look forward to using it

[JoeQuaker]

Yeah that's impressive! If I can't sort out the issue with my CD-ROM I may end up breaking down and sending him mine too