REPAIR GUIDE - TurboDuo: Sound Fix

[Keith Courage]

Hmm, that sounds correct then. You should have the same reading on the main op amp as well. Sounds to me like the problem is bad traces for one or more of the audio capacitors. I honestly can't suggest which to check next since I didn't do the cap job to know which ones had more leakage or pads lift etc...

[thesteve]

for chiptunes the only amp in play is IC506
check voltages on pin3 (3.88) pin4 (0) pin5 (3.88) pins 1 and 7 (3.88)

[Zer0-2k11]

Ok just got out everything and this is the results,

Multimeter set to DC voltage

Pin 3 = 3.89
Pin 4 = 0
Pin 5 = 3.88
Pin 1 and 7 = 1.45

I think we are getting onto something

The positive pad on C614 did get lifted and i patched it to the closest via with some 30awg kynar wire

[thesteve]

check pins2 and 6
they are your inputs
they feed from C613 and C614, but also get voltage from pins 1 and 7
should be 3.8

[thesteve]

also check voltage at C322
look for black via's by C322 if not 3.88

[Zer0-2k11]

Ok im getting 4.2v on both pins 2 and 6. For C322 im getting 0.030 I don't see any black vias but i am looking

[thesteve]

R321 should be 8v and 3.8
it gets the 8v from a via from the amp power you checked earlier
R321 and R322 are the voltage devider for c322

[Zer0-2k11]

I can see the power rail (Thick trace) that it links too on the IC506 amp . It seems like im not getting any continuity between the via that connects to pin 8 on the IC506 and the positive lead of C322. One of the 2 vias that connect to C322 must corroded damaged. I can't really check the via that connects to C322 as its underneath the 4558 on the bottom side of the motherboard. Would it be safe to link them together with some 26 awg kynar wire?. The via by C322 did look kind of black.

[thesteve]

R322 is the ground side
R321 connects to the power trace

[Zer0-2k11]

Sorry, i did check R321 and im getting the same voltage reading (0.030).

*EDIT* Ohhh i see what your saying. im not getting continuity between the left side of the resistor of R321 and pin 8 on the audio circuit amp.

[thesteve]

looking at R321 one side goes to C322 and R322
the other side goes to a small via, and directly to a large power trace (pin8 all audio amps)

[Zer0-2k11]

Sorry i know what you mean now. im not getting continuity between pin 8 on the amp from the audio circuit and the side of R321 that connects to it

[thesteve]

jumper is fine, once your sure your jumpering the right point
what i like to do is push a wire through the bad via and solder both sides

[Zer0-2k11]

Steve, your a miracle worker!, that was it. Thank you, the sounds working with HuCards

But i got no audio with Far East of Eden except the sound when a dialog pops up just after i press the  run button. Cant get past that dialog but i think i just need to tune the pots a bit more

[Kid Compile]

Sorry for the strange first post - I used post a little bit on an older version of the board back around 2005, my username then was Kakizaki, but for whatever reason that account doesn't work any longer. I suspect due to inactivity.

Anyway, my TurboDuo is starting to falter here and there, mainly sound issues and I suspect it is probably due to bad caps based on everything I have read both here and elsewhere. I am also getting a bit nervous about my lens as the poor guy seems to hang up or take an excessively long time to load CD games.

I've noticed that a few members here repair systems but I didn't want to PM anyone out of the blue without posting first.

I was also looking for a little advice. I was really pretty bummed when this first started happening, and was looking to replace my Duo rather quickly (one of my favorite systems), especially since I made a point of picking up a few extra PC Engine games the last time I was in Japan earlier this year.  I also thought it might be an excuse to snag a Duo R or RX. They just look so damn rad. I was on the cusp of snagging a modded Duo RX from Doujindance on Ebay, but after reading some posts here, I am not so sure anymore. Should I steer clear of Doujindance and try and find someone else to just repair my TurboDuo? I wouldn't mind a region mod, but it isn't a necessity for me right now. I also have a CoreGrafx that I use to play HuCards.

Thanks for the input!