REPAIR GUIDE - TurboDuo: Sound Fix

[ceti alpha]

Did you fix it yourself? If you know what caps got changed, that would be very helpful!

Unfortunately not - I sent my Duo to D-Lite to get fixed. I'm getting it modded as well, so there was really no point in trying fix the audio issue myself. But I'm sure someone here will be able to help you more.  Sorry I couldn't be more help. I know all too well how frustrating the sound issue is. 

[Nintega Turbine Trio-CBS]

Oh damn. I just bought a black Japanese PC Engine Duo from ebay last night. I hope my system works fine. 

[CkRtech]

This thread has been a great resource. Thank you to all that contributed. It made repairing the sound issues with my Duo seem like child's play.

For the record, I replace the main caps mentioned in the images earlier in the page, but those weren't enough. As a general rule of thumb, it is probably a good idea to replace all your caps in that amp area - this has been mentioned before, but I just wanted to repeat it. That said, I'll give you the extra details on my issue.

I was experiencing somewhat crackling audio of the CD playback during the first minute or two of gameplay. It would clear up after that & seem just fine. In addition to the caps mentioned earlier in this page, I replace four other caps:

100 uf 10V
220 uf 16V
470 uf 16V
1000 uf 16V

Each were replaced with Radio Shack caps (I believe they're all 35V). The early crackle went away, and it seems like I had a much wider frequency range of playback (i.e. bass was much clearer). I have marked those caps on the "cap map." I hope those that created this image don't mind my modification:

[nat]

That's curious about the 1000uf cap needing to be replaced. That type of cap isn't prone to leakage or failure.... Are you sure it was necessary in your case, or were you just covering all your bases?

Speaking of the sound issues, I recently discovered a cap elsewhere on the mainboard outside of the op-amp cluster is directly linked to certain sound issues. Specifically, if you are having problems with all of the following: ADPCM sample playback, PSG, and redbook. The cap in question wasn't previously known to be part of the audio circuit at all and I have a feeling is the culprit in the cases where replacing all that caps in that circled area and to the right of the circled area don't fix the problem.

You have to remove the FCC shielding to even see this cap. It's kind of in the middle of the board, out in no man's land by itself. Like the component I discovered to be responsible for video failure on the TurboExpress, this is another innocuous little guy you'd never suspect. I'll post a picture up in the next couple of days that shows where to find the little rascal.

[CkRtech]

Hey nat -

No. I just grabbed all the caps in the area just to be on the safe side. The only ones Radio Shack didn't carry were the 330uf (x 2) that are not labeled in the picture.
....plus I just got a new soldering station & was dying to try it out. 

[Duo_R]

Anyone have the other cap values mapped out on the board? My good fortune didn't last forever, the sound eventually went out again. I looked at the other caps on the board today and noticed some that didn't look good. However, I am very confused with some of these values:

22
6a
25m

100
6s
25a

I take it that these are 22uf and 100uf caps, but what the hell do the the other codes mean? What is the voltage for these? I have a personal friend who is a electrical engineer and warned me about going too high on the voltages of the caps that I replace with so I wanted to match these up.

[Duo_R]

never mind - I found the full list of specs for the caps. Update - I replaced some more and now my Duo seams to be doing better (for the moment). After about 30 second warmup the sound is decent. There is a little scratchy fade in sometimes, but the longer the system is on the better (so suspicious that there is another bad cap). I placed an order for some more caps, so will just keep replacing...but I installed a Blue LED!!!

[Duo_R]

Any updates on that cap?

That's curious about the 1000uf cap needing to be replaced. That type of cap isn't prone to leakage or failure.... Are you sure it was necessary in your case, or were you just covering all your bases?

Speaking of the sound issues, I recently discovered a cap elsewhere on the mainboard outside of the op-amp cluster is directly linked to certain sound issues. Specifically, if you are having problems with all of the following: ADPCM sample playback, PSG, and redbook. The cap in question wasn't previously known to be part of the audio circuit at all and I have a feeling is the culprit in the cases where replacing all that caps in that circled area and to the right of the circled area don't fix the problem.

You have to remove the FCC shielding to even see this cap. It's kind of in the middle of the board, out in no man's land by itself. Like the component I discovered to be responsible for video failure on the TurboExpress, this is another innocuous little guy you'd never suspect. I'll post a picture up in the next couple of days that shows where to find the little rascal.

[Redfield1]

Thanks for the great job.

My Duo got the audio tracks back.



   ... Red ...

[Duo_R]

Update - how is the sound fix working? I am nearing full replacement of the entire caps. I got full sound, but an intermittent scratch sound. Funny thing is the scratch get's better and better, then I replace another cap and it gets worse. We will see how things go after full replacement.

 

[oldschoolgamer1989]

Will 10 uf 35 v caps work?

[Duo_R]

that diagram he has is showing the cap values he used, but 10uf 35v would work fine. The value of the caps could be between 10uf 16v - 10uf 35v (i personally wouldn't go higher).

[oldschoolgamer1989]

Thanks for the tip!!

[oldschoolgamer1989]

Replaced the first 2 caps today and still no music. Which ones should i look at next?

[oldschoolgamer1989]

Just a note: After leaving the unit on for about 10-15 mins. The music finally starts playing. what next?