I'm working on this TurboDuo. I've recapped about a half dozen in the past & a few I had to repair broken traces, one I even had to replace the 4558 OpAmp.
When I got this one it had audio for a second & then it would completely cut out, with both Hu Cards & CDs, through the headphone jack it plays the audio very low. If you turn it off & on again it has no audio at all but if you let it sit it gets the audio back for a second again then cuts out. When I opened it up I saw a few caps had leaked but not that bad, except C322, which had corroded so bad it fell clean off the moment I touched it. Usually when I recap these I test them as I replace caps to see if I get an improvement or the problem gets worse so I know what went wrong where. This case it never got any better. I’m using the same caps I’ve always used so quality of caps shouldn’t be the issue. So far I’ve:
-Replaced all the caps.
-Pulled most of them back out, test them & check adjacent traces for breaks, no breaks all caps are good
-Replaced the 4558 at IC 506 & 507
-Replaced the Volume Balance IC M51131L at IC 505
-Replaced the ceramic resistors above C322. I tested it without the resistors & I got audio for a little longer before it cut out. I was applying pressure unintentionally to the board & the moment I let up the audio cut out so I don’t know if it was the pressure that did it or the missing resistors. When I replaced the resistors it went back to the same issue. I haven’t been able to replicate this with pressure a second time.
-I re-flowed IC 515 to see if that would do anything, nothing.
I’m at a loss at the moment what to try next.