[Almost solved] Another PCEngine DUO without CD sound

[riper]

Hi all,

First of all, forgive my English. It's not very good.

That's my first post here, but that's not the first time that I read your posts. If I'm not wrong, in the past, it was not necesary to have user and password to enter and read the posts. Maybe I'm wrong.

Maybe one or two years ago I had a japanese PCEngineDUO with sound/cap problems. The only thing that I had to do was: remove old leaking capacitors, clean the board and put the new ones. All of them. And it worked like a charm! But for some reasons I had to sell it.

But the destiny is stubborn. Now I have another faulty PCEngineDUO with the same problem than the other one. But this time the cap replacement didn't do the trick.

Let me start for the main problem: sound fron the CD.

Talking about HuCard games, I can play without sound problems. I can hear music and fx's crystal clear. It doesn't matter if you hear it using AV output or headphones output. 100% clear (or something like that).

Talking about cd games, I can play to any (backup or original) game without problems (regardless of the sound problem). I mean that the cd spins without problems, game boots and plays fine and fast... but no sound.

I think that my problem is related to famous error #1: CD plays and loads fine, but all redbook audio (soundtrack, not sound effects) is dead.

Some examples:
Castlevania Rondo of Blood.
- I can hear de Konami logo sound.
- Intro starts, but no sound (no voice, no music, etc...)
- When I start playing I can hear the whip sound, the skeletons die, etc...

Y's 1 and 2.
- I can not hear anything until I start playing. No sound on the intro scene. Maybe some seagulls.
- Once into the game, I can hear some music, provably not readed from the CD.

Dragon ball.
- I can hear Goku and other characters saying something, but no background music.
- No music during the intro scene.

I hope that this examples helped you to understand my problem.

What I have done?
I have removed all the caps and replaced them by new ones.
Before mount the new ones, I've cleaned the board using isopropilic alcohol.
I have used flux to ensure a good soldier of the capacitor.
I blent the legs of the capacitors this way ][ for better bond between capacitor and board.

It's true that before that (cap replacement), the sound through the AV output wasn't so powerful than now. The volume of my TV can be graduated from 1 to 100. I usualy can play other consoles (or TV programs) at volume of 25. Before the cap replacement I had to play to the PCEngine with a volume of 50 or more.
After the cap cap replacement I can play with a "normal" volume. So I won something. 

I have to say that I don't exactly know the diference between ADPCM and redbook audio.

Just 2 more clues about the problem:
1. using headphones, if I close my eyes and try to listen carefully, I can hear something (Dragon Ball intro, Lords of Thunder guitars, ...)
2. The same if I try to play music CD: very very very very very soft volume.

So, here my questions:
- Considering that the games load fine , it is possible that the problem is the laser head?
- I've readead that there are some IC's involved to the sound. Like M5205OKI, M51131L, BA6290A and the OPamps 4558. But maybe only few of them involved exclusively to the "FX" sound (that works fine in my case) and I don't have to check them.
- Any idea about how to proceed in my case? What do I have to check? I have a multimeter so I can give you any lecture you want.

Sorry for that big post and congratulations for that great site.

[xinsizionx]

I have read that this is a heat relates issue. I could be wrong tho

[riper]

I have read that this is a heat relates issue. I could be wrong tho

Thank you xinsizionx for your answer.

Now that you mention it , I want to say that the sound problem occurs from the very first cold start.
Both BA6290A seems cold, even after half an hour of playing.

I feel that there are ic 's specifically related to the sound generated by the console (is this the ADPCM ? ) and on the other hand the "sound" read from the CD (is this the redbook ? ) . At some point all sounds are mixed to form the whole game audio .

In my case it seems that at some point the sound from the audio tracks on the CD are lost.

I mean that, for example, if M5205 OKI is not related to CD track sound, maybe I don't have to check it.

I've found this information:

For CD audio (sourced at U103 PCM decoder), start at U201 (DAC), come out stereo to U202 filter (caps C205,C206 significant here),through U203 amp/filter, through U504 audio gate, into U505 (caps c617,c618).  Out U505 (through caps c613,c614  -- also, c616 sets frequency response) to U506, out U506 (caps c604,c610) to AV output connector.  Same signal also fed to U507 amp/filter (through caps c670, c671), then output (via c678, c679) to headphone connector.  U507 also uses caps c675 and c676 to set its filter operation. 

For game audio (sourced by U901), come out stereo through caps c878 and c879 into U506, continue as above. 

I will try to trace it, but maybo I'm not skilled enough to do it.
And also I don't know the difference between "for cd audio" and "for game audio".

Thank you a lot guys.

[xinsizionx]

http://www.pcenginefx.com/forums/index.php?topic=960.0

[riper]

http://www.pcenginefx.com/forums/index.php?topic=960.0

Thank you. That's the "main" thread, I know. I've readed it already, but I'm going to read it again I think.

But I'm here with bad news:
When I thought I had found the source of the problems it ends like when I was at the first day. Let me tell.
As my previous quote say, there are two or three IC's at the "side B" of the board in charge of the CD sound. Those IC's are IC503 and IC504.
I've decided to lift them and see what can I see... and what was my surprise that I found a lot of corrosion and capacitor liquid. Below each of them.
I've used flux and isopropilic alcohol to clean the zone and I mounted the IC's again.

The results are:
- Still no music cd sound
- Now I need to rise again the TV volume to 50 to hear the HuCard sound.

I'm thinking about to do the dishwash method, but I'm little bit scared. I think that I have to remove the NEC supercapacitor before put the board into the dishwashing machine.

I'm losing a little hope to fix the problem. 

[xinsizionx]

any trace damage?

[riper]

Maybe ... but I have not seen.

[Keith Courage]

Check the traces around these two caps(cirlced in red). Generally bad traces here cause CD audio issues.
image hosting 10mb limit

[riper]

Check the traces around these two caps(cirlced in red). Generally bad traces here cause CD audio issues.

OK Keith, I'll do it that night.
Thanks.

EDIT:
Can I use something like this to find where the problem is?


EDIT 2:
I've decided to split my problems into 2 lines of investigation to understand why it happens.
The first one (and easiest, I think) is try to guess why the sound on the TV is weaker than headphones.
And the second one (most dificult one) is try to find the reason why I have no audio CD.

I'm trying to make a graphical transcription of this text, because I think that is the clue:

For CD audio (sourced at U103 PCM decoder), start at U201 (DAC), come out stereo to U202 filter (caps C205,C206 significant here),through U203 amp/filter, through U504 audio gate, into U505 (caps c617,c618).  Out U505 (through caps c613,c614  -- also, c616 sets frequency response) to U506, out U506 (caps c604,c610) to AV output connector.  Same signal also fed to U507 amp/filter (through caps c670, c671), then output (via c678, c679) to headphone connector.  U507 also uses caps c675 and c676 to set its filter operation. 

For game audio (sourced by U901), come out stereo through caps c878 and c879 into U506, continue as above. 

For ADCPM audio (sourced by U502), come out mono through cap c652 to passive filter (uses c623), to one-half of U503 amp  , out U503 (cap 653) through passive filter (uses c621) to other-half of U503, into U504 audio gate (both channels), continue as above.

But sometimes I have problems to understand that "in/out/through" information.
I have created this flow chart. Can some guru take a look and tell me if the graphic is the correct transcription of the text? (sorry about the quality)



Returning to the subject of the weak volume through the AV output, if my graphic is correct, the problem should be on the U506 or forward. Because at this point the signal are splitted into two, and the one that is used by the headphones is fine.

What do you think about?

[Keith Courage]

So all the audio is low through the AV port? If so check what the voltages are on the 4558 OP AMP that is located near the AV port. The top right pin should read around 3.8V. IF not then there is either a bad trace or corrosion under the amp that needs to be removed.

Also, double check that the bottom right pin on the same amp is getting a good ground. I've come across this shorting out as well.

[riper]

Hi,

First of all, my lectures on the IC506 (4558 op amp).



Do I need to wire from leg 4 to another ground?



I have created this table to show how capacitors C604 and C610 affect to the overall sound (using HuCard).
Here you are:



Just for public interest, I have another table but with the caps c679, c678, c675, c674, c670 and c671

Thank you.

EDIT.
As you asked, I've checked c612 and c616 surroundings and all traces seems good. But I'm not very good looking at this. 


IT WORKS!!!
I've found the problem for the audio CD.
As Keith said, the problem was near to c612 and c616, but was a VIA!
With DMM I noticed that this point hasn't continuity from side A (caps side) of the board to side B (solder side).
I decided to link this "VIA-side-B" to it's destiny and... voilá! Sound on Lords of Thunder, Ys 1&2, Dragon Ball, Castlevania...
Now I'm playing to Castlevania for 15 minutes. All seems to be fine and working properly. Let's cross my fingers!

I'm still having the low volume problem on the Left channel using AV port... but that's not a problem because I want to modify the wire to take the audio from the headphone jack.

Here the fu***ng VIA.



Thank you so much Keith.

AFTER 2 DAYS
Today I was playing to Castlevania and the music has gone.   
If I die, the music starts again... but it disapear in few seconds (it could be 5 or 15, it depends).
I think that this problem is related with that the PCEngine DUO has no error correction reading the CD tracks, and if there's any scratch or problem on the CD surface the DUO stops reading. That's why it starts reading again when I die or in a new stage.
Well, I need to try what happens if I use originals, because my Castlevania is a backup (using Tayo Yuden supplies).

.