REPAIR GUIDE - TurboDuo: Sound Fix

[Charlie]

NPN it is, the damn "arrow" on the emitter is so small, I can't really see it; probably should have looked up the part number to verify.

Charlie

[thesteve]

so i gather you have the schematics and part lists for the DUO?

[chop5]

A sound issue duo me and steve fixed over the last few weeks over chat.

symptoms:
Almost zero sound but if tv is volume on maximum can hear it softly,same for headphones. Some volt meter reads showed it was this op amp chip:

http://img.photobucket.com/albums/v238/jetbue7/Image1segagamer.jpg

Replaced with near identical op amp chips I got from ebay and sound was restored but static developed and slowly sound will fade in and out depending on the duos mood or me touching the board or touch with toothpick in sensitive area. Much meter and sound probe testing found the trace and some via's going to the new chip were bad. You can see a blackened via in the first picture near pin 5 of ic503. The second bad trace and via was to chip leg 3 of the ic503. bypass was made:

http://img.photobucket.com/albums/v238/jetbue7/Image2sgr.jpg

The other wire on chip leg 4 was for ground when we thought the ground trace was bad.
The other side of the board:

http://img.photobucket.com/albums/v238/jetbue7/Image5sgr.jpg

The damaged via near pin 5 was fixed with wire and solder to both sides after a bit of scraping with a tiny star screwdriver till shiny copper was seen.
the trace and via of pin 3 was just bypassed shown in second pic. The trace for pin 3 lead to those 2 resistors r321 and r322,it forked into both of them so  used a small drop of solder connecting them to the wire like in a T formation.
Static is all gone full sound restored. thank you steve

[roflmao]

You guys rock.

[mrchuck999]

Hi Guys: I've been reading this thread today because my USA DUO suddenly has very-soft red-book audio while the chip sounds (guns) are loud and clear.  with headphones I can just hear a Music CD play. But a game fire-shots are loud and clear.

This was called problem #2 in an early post. But I never found a clear documented cause-solution. Has any one fixed the "very-quiet" red-book audio (music)? It seems this issue should be caused by a cap dedicated to the CD red-book audio and not the same as over-all low volume.

Thanks for your wisdom. I love this site and all the work from Red-ghost & D-Lite. You know you're awesome!

[BlueBMW]

Hi Guys: I've been reading this thread today because my USA DUO suddenly has very-soft red-book audio while the chip sounds (guns) are loud and clear.  with headphones I can just hear a Music CD play. But a game fire-shots are loud and clear.

This was called problem #2 in an early post. But I never found a clear documented cause-solution. Has any one fixed the "very-quiet" red-book audio (music)? It seems this issue should be caused by a cap dedicated to the CD red-book audio and not the same as over-all low volume.

Thanks for your wisdom. I love this site and all the work from Red-ghost & D-Lite. You know you're awesome!

At this point, all these Duos are at the age where most if not all the capacitors have started to leak/dry up/ fail.  As such, if you're going to open the system to replace any of the caps, it would be prudent to go ahead and replace them all.

[thesteve]

i have seen some corroded traces/vias do that as well as bad caps

[boliver]

in case its useful to anyone, i had the too quiet cd audio problem with my Duo, and i was able to fix it by replacing the top rightmost 22 cap.

[Nagoyan]

Thanks to everyone for all the great info in this thread! My Duo's CD sound recently started to go and replacing the caps seemed to fix the problem. However, while soldering in one of the post-amp caps, one of the solder pads became loose and I'm intermittently losing one of the audio channels. Are there any methods out there I can use to get that pad fixed back in place?       

[thesteve]

the best fix for a loose pad is to run a wire to the run, or another point it connected to

[Nagoyan]

Thanks for your help! I'm pretty new at this sort of thing, so is the run similar to the trace on the PCB? Just to the side of the square-shaped capacitor trace there's a small solder point and I wonder if that's the spot I can connect a wire to from the capacitor terminal. Figure I'd better have a plan B worked out if any more pads go when I replace the rest of the caps in the future.   

[thesteve]

the term run and trace are interchangable

[Nagoyan]

I see. Thanks again for the info!

[gamereviewgod]

Thanks for the thread! I fixed my Turbo Express earlier in the week and now my Duo has redbook back... partially. I only have audio out of the right channel. I bought a new AV cord and it's still doing it. I'm assuming it's one of the other caps, but what I can't figure out is how to get the metal plating off. It looks thickly soldered to another component.

Can it just be cut out or does it serve a purpose? I'm assuming the two wires soldered to it are just the grounds, right?

[thesteve]

i move the 2 wires to the lower shield and resolder.
the top shield is soldered to the controller port and will need to be heated/unsoldered.
the system runs fine without it, but i reinstall it when done