REPAIR GUIDE - TurboDuo: Sound Fix

[gamereviewgod]

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

Is it just an RF shield?

[thesteve]

yes its  just an rf sheild

[gamereviewgod]

Just finished. The 22uf one sitting under the shield was A MESS. It has leaked everywhere. Took me 10 minutes just to see clear metal on the pad again. After all of that though, I have full stereo audio back, and I'm happy. Thanks again to everyone who has worked on this!

[thesteve]

your welcome

[Bernie]

This place is awesome.  Its good we have the techs here that we do.  I dont want to perform any kinda surgery on my systems.

[Mystery]

Hi guys

I recently got my hands on a PCE Duo which was supposed to be working, except for missing sound. I bought it and thought that a simple cap replacement would do the job.
After some online research I stumbled upon this awesome forum and after reading this thread, I was pretty sure that the system could be easily repaired.
When I opened it up, I saw that one of the previous owners already replaced quite a handful of caps around the 4558 amps. I got a little bit worried.


Long story short, I did a full cap replacement (finding a few additional leaky caps in the process), but unfortunately, the problem still persists.

I have full sound from HU card or CD (redbook audio, adpcm etc.), but it's almost inaudible, both on the AV out and the headphone jack.


What could be the cause of this?
I'm considering replacing the 4558 op amps. Could that work? Or does the current problem suggest a different approach/solution?

[BlueBMW]

If you have a meter...  look up the data sheet for those 4558 op amps and check the power supply pin...  we've had a few units where cap fluid causes the transistor that powers some of the audio chips to fail.  Result is no / very low sound.

[Mystery]

Yes, I've got a meter. I checked all six 4558 amps and they all get power.

I made some progress, thanks to some very helpful PMs.

I got regular SFX and CD audio working on the headphones, by hooking the output of the upper 4558 (close to the AV port) amp to the L/R channels on the headphone jack. It's just a workaround and not really a fix, but for now it's working.

However, the ADPCM sound is still very faint. I can (barely) hear it, if nothing else plays, but that doesn't really do it for regular gameplay
I put a wire from the M5205's pin10 to one of the 4558 input pins (not permanently, just for testing the ADPCM output) and I got crystal clear sound from it. However, just on one channel, and adding a trace to the other input pin screws the whole sound up.

[thesteve]

2 points
1. adpcm is 1 channel.
2. it sounds like you losing it around the AVC.


the avc is voltage controlled, the last one i did wasnt getting the control voltage to it due to a bad via

[Mystery]

2 points
1. adpcm is 1 channel.

I know. Perhaps I didn't phrase my attempt to get it working correctly.
I was just stating, that when I put the ADPCM to one of the AV amp inputs, it came out crystal clear, but when I put the same output from the ADPCM pin10 to the other AV amp input at the same time, the whole sound got messed up.
I'm aware that it's not stereo, but I still have to get the signal on both channels somehow

2. it sounds like you losing it around the AVC.
the avc is voltage controlled, the last one i did wasnt getting the control voltage to it due to a bad via

Anything I can do to test that theory and if necessary fix it?

[thesteve]

i dont have the data sheet in front of me for the AVC (the ZIP chip by the heatsinks) but i traced the sound to its inputs, with nothing out.
checked the voltages on the control pins per the data sheet.

[SNKNostalgia]

Sighhhh, my US Duo's right sound channel is quiet. I didn't even touch the system in like 3 months. It worked fine last time I played it. At least I can play it in mono (left) sound for now. I need to get another 3.5mm to RCA cable and use it with headphone output to make sure it is just the AV out or the stock Duo AV cable. Fun, fun, fun!!! Man US Duo's suck ass!!! Seriously though, up there with RROD on Xbox 360s... hell probably worse.

[BlueBMW]

Nahh... Duos arent worse than RROD.  We can fix them without expensive crazy reball equipment!  And, it did take some 20 years for them to fail, not 1 or 2 like those silly xboxes.

[Necromancer]

Man US Duo's suck ass!!! Seriously though, up there with RROD on Xbox 360s... hell probably worse.

Dried out caps after twenty years equals sucks ass? 

[SNKNostalgia]

Actually, I heard of a lot of Duo systems sound going out 10 years ago. So I am going to more than assume this has been going on for a while now.