REPAIR GUIDE - TurboDuo: Sound Fix

[meka]

I have the exact same problem with my Super CDROM2

[BlueBMW]

I have the exact same problem with my Super CDROM2

Then step on over here and start changing your caps!

http://www.pcenginefx.com/forums/index.php?topic=9544.0

[meka]

Just replaced all the caps on the Super CDROM2 and it works great, thanks for showing me the post and to the person who posted it, it really helped.

[ogre]

I finally got around to changing all the caps on my resurrected black pc-engine duo. Before I had no sound whatsoever , and now the only sound I have is crystal clear loud redbook audio. I have no hucard sound, and the only other sound I can hear is in lords of thunder when the character gets hit or dies. The system has no other issues and loads any game perfectly(Actually quicker than my Duo-R). All the caps are new, and as far as I can tell are working. Does anyone now what chip regulates the hucard audio?

[thesteve]

the hucard audio is not regulated
its mixed after the AVC chip (the ic behind the heatsinks with pins on one side only)

[ogre]

Is that the chip amplifies the audio that the hudson chip outputs? I am only guessing this may be the problem as redbook audio works, as does some of the voices in Fatal Fury Special. It does sound like it is trying to produce sound, but only faintly. This just frustrates me as before the power brick broke it was working perfectly.

[thesteve]

no that chip lowers the cd audio before mixing in the Hudson chip.
the Hudson chip is not dealt with separately at all

[ogre]

Ok, so I guess I will just have to trace the audio from the HU6280. I am definitely no expert, but all info points to that producing the audio. The chip obviously must be working as it is also the main CPU. If no chip amplifies the PSG coming out of this does it go through any filtering caps?

[thesteve]

[thesteve]

thanx to charlie for the schematic

[ogre]

Thanks. Now I will have to do some digging.

[notsonic]

just want to add some more to this thread and see if anyone has any suggestions.

the original condition of my duo was low sound. i do not know if it got better or worse after being on for a while as i didn't test that.

i replaced the two post amp caps with 10uF 35v caps from radioshack. sound levels were back to normal. sound quality was maybe a little shitty/peaky sounding but that could just be how it is, i forget. cd audio was perfectly clear. i left it on for a few hours and it started popping, both through the av out and the headphone jack.

I'm going to go and replace the pre amp ones and the other caps people have mentioned to see if that helps. none of the caps look physically bad, though they are so small its entirely possible theyve leaked and its not 100% obvious.

also, does anyone have any tips for removing these kinds of caps?

[thesteve]

press them against the board and twist back and forth

[ApolloBoy]

press them against the board and twist back and forth

This is the technique I use as well. Gets them out every time and there's no damage to the board this way. Sometimes you'll even pull the old cap legs right off the pads which makes things easier!

[Jugbug]

I'm new as a poster around here, but have been reading up for awhile.  I just wanted to give a big thanks to this thread I was able to restore my Duo's audio.  It was having issues for a long time and then was finally silent.  I plan on doing a total capacitor replacement when I've got some time.  Any advice from people who have done this is welcome.  My main concern is if I go radial if there's enough room under the shield, or if I go SMD if the caps will be too large for the pads.  Thanks again, and here's hoping my Duo at least lives longer than I do  


Edit:  Thanks for the advice, BlueBMW.