PC Engine GT - Video / Audio Issue

[PIXeL_92]

Hi All,

I hope someone can help me with this issue.

So I imported a few PC Engine GTs from Japan as junk.

All but one I have managed to repair, this one was by far the worst.

It was covered in battery juice that much when I used some IPA to clean the controller board up all the carbon pads and PCB screening just washed off the board, luckily Tawy sold me one of his new ones.

So the issue I have is whilst video is working the brightness wheel is so sensitive, I would say the whole range of brightness is all done using only 5-10% of the wheel movement and there is no audio.

I have removed and replaced each cap, checking values and polarity these are 100% correct.

Next thing was looking for damaged traces / vias and I did find one near the transistor marked Q500 and I repaired this via  using some enamel wire from the positive on the large cap in the corner through the via and directly connected it to the resistor(before this I had zero video just Backlight.)

Looking around the audio area I can't find any damaged traces or at least any that stand out.

I did take the brightness and volume pots off and there was a small amount of corrosion underneath them so I'm hoping it's as simple as replacing them, I did try what I think was a DMG GB pot but no joy in sound returning either through the speaker or headphone jack.

I did also clean the whole board in an ultrasonic cleaner just to try free any loose corrosion.

Thanks in advance.

[tawy]

When replacing the pot try solder together the pin like this :
https://gbatemp.net/threads/gba-volume-wheel-replacement.538037/
Maybe the pce audio amplifier only get value from the pot itself without attenuating it.