Duo Sound Issue Thread #12,054,345,001

[some stupid japanese name]

Long story short: My buddy has a Duo and has had no issues with it. I offered to recap it because we all know whether they work or not, at this point they should be recapped. I reiterate, until I touched the thing everything worked properly.

I ordered a kit from Console 5 and recapped it today. Thankfully though there were several leaky caps there was no board damage. No pads lifted or anything. It was about the smoothest recapping I've done (which up to this point has only been Game Gears and my Laser Active Sega Pack).

Hooked it up and threw a card in it, everything was kosher. Popped a CD in it, extremely low audio. Checked the caps that I believe have to do with audio (C604, C610, C325, C323, C613, C614). They were all the correct values and polarity (according to C5's list and guide) and soldered tight. I even took them off and put them back on to be sure. I checked the C615, 306, and 305 as well. Everything seems to be proper.
Is it possible to have a bad new cap? What else should I be checking to trouble shoot?

[SignOfZeta]

I'm assuming you don't have a meter?

[some stupid japanese name]

I do. But aside from checking continuity, I've no idea how to use it.

[Keith Courage]

There has to bad connections to some of the caps. Check the ones that had leakage underneath the old caps when you removed them.

The ones that are usually the culprit dealing with CD audio are the 47UF  and 22UF cap in this area. Circled in red. https://postimg.org/image/wqmpf594d/

Check what voltage the Positive legs have and then the voltage the via holes to them are at. The 47UF cap should be 7v. I'm pretty sure the 22uf should be at 5V

[some stupid japanese name]

Will do, thanks for the advice!

[Punch]

Best nickname.

[some stupid japanese name]

Checked the caps with a buddy's ESR meter, and they're fine. Checked continuity on those two caps, and it's fine. Checked continuity on all the caps around the amp. All checks fine.
Compared voltage on this machine and the PCE Duo I got from KC a year and a half ago and they were the same.
For giggles, I even replaced all the caps with leftovers I had from Game Gear kits (same mf, higher voltage in most cases) and it's the same deal.
I don't know what else to do.

[mario_pic]

threw hole damage trace the ground leads and power leads

[Keith Courage]

There still has to be bad traces or shorted vias somewhere in that area. Check the voltages coming from the 4558 op amp that sits underneath those two caps I told you about. Then also check all the via holes in that area to make sure the traces to each via has the same voltage as the via hole itself.

Just to recap you are only having low audio on CD games correct? Hu card volume is absolutely fine?

If all volume is low including hu cards you should be looking for shorts around or near the 4558 op amp right by the AV jack.

[some stupid japanese name]

Correct, CD audio only is extremely low, like if you crank the volume all the way up you can hear it (underneath the crackle of my poor GXTV's speakers).
Hu card volume and sound effects on CD games are perfectly fine.
Will do as you advised and report back.

[MobiusStripTech]

I second what Keith is saying. I just fixed one of these last night and it was the opamp under the caps Keith mentioned. There was a ton of cap goop underneath it. Good luck.

[HuMan]

Correct, CD audio only is extremely low, like if you crank the volume all the way up you can hear it (underneath the crackle of my poor GXTV's speakers).
Hu card volume and sound effects on CD games are perfectly fine.
Will do as you advised and report back.

Sounds exactly what happened with my Duo, but it was with HuCard sound. In my case, there was a faulty power-related resistor that was causing a significant voltage drop on the sound amps nearby, causing the super low audio issue. That was after I fixed some corroded vias and cleaned up a 8551 amp that had electrolytic goop underneath it from a leaky capacitor (amp was under the board near the super cap).

I suspect on your Duo, the CD audio amps aren't getting enough power to turn on. Check the board again for corroded vias (sections of trace that transition from board side A to B) and make sure your caps have good continuity to wherever they're going.