Midway soundboard got me stumped (Jam, MK1, T2)

UnknownMK

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I picked up this board recently in need of repair and I'm out of ideas. It "works" (plays all music and sound fx) but you have to have the volume cranked all the way up in order to hear anything. When I got it, it had the original caps which leaked causing some trace damage and no fx, mostly around the oki chip. Here's what I've done so far to troubleshoot:
▪FULL cap kit (ignore the original axials in the pic, they've since been changed)
▪replaced main amp (appears to be working fine, is barely warm to the touch as it should be) and all 3 op amps
▪fixed all broken traces I could find (4 so far)
▪replaced the oki chip (this restored all sound fx)
▪swapped all socketed chips marked with an "X" in the pic with one's from a working board
Screenshot_20250706-013018_Facebook~2.jpg
▪tried 3 different known working volume pots
▪tried 2 different known working ribbon cables (yes they were plugged in the right way)

Are there any other components that could possibly cause this volume issue that I missed in my troubleshooting? Could it possibly be a resistor out of tolerance/open or a bad cap (one of the little yellow ones that are all over the board), or yet another bad trace that I missed?
 
I picked up this board recently in need of repair and I'm out of ideas. It "works" (plays all music and sound fx) but you have to have the volume cranked all the way up in order to hear anything. When I got it, it had the original caps which leaked causing some trace damage and no fx, mostly around the oki chip. Here's what I've done so far to troubleshoot:
▪FULL cap kit (ignore the original axials in the pic, they've since been changed)
▪replaced main amp (appears to be working fine, is barely warm to the touch as it should be) and all 3 op amps
▪fixed all broken traces I could find (4 so far)
▪replaced the oki chip (this restored all sound fx)
▪swapped all socketed chips marked with an "X" in the pic with one's from a working board
View attachment 831294
▪tried 3 different known working volume pots
▪tried 2 different known working ribbon cables (yes they were plugged in the right way)

Are there any other components that could possibly cause this volume issue that I missed in my troubleshooting? Could it possibly be a resistor out of tolerance/open or a bad cap (one of the little yellow ones that are all over the board), or yet another bad trace that I missed?
Update to this:
This is an update post to my previous repair inquiry on an MK1 soundboard. I have fully restored the volume, there was a broken trace from the negative leg of C87 to C91. I've restored 99% of the functionality. The last little bit is the sound is just a tiny bit off. The most noticeable when initially starting the game and when connecting with an uppercut or a roundhouse kick. In the video it seems like there is no sound effect for the punch or kick but it's there, just really muted. However all other sound fx and music seem to be present and correct. There is no "bong" when going into the soundboard test either. Anyone know where/how that tone is generated?
 
Update to this:
This is an update post to my previous repair inquiry on an MK1 soundboard. I have fully restored the volume, there was a broken trace from the negative leg of C87 to C91. I've restored 99% of the functionality. The last little bit is the sound is just a tiny bit off. The most noticeable when initially starting the game and when connecting with an uppercut or a roundhouse kick. In the video it seems like there is no sound effect for the punch or kick but it's there, just really muted. However all other sound fx and music seem to be present and correct. There is no "bong" when going into the soundboard test either. Anyone know where/how that tone is generated?
U15 AD7524 DAC

it's the chip above the Oki 6295 PCM
 
U15 AD7524 DAC

it's the chip above the Oki 6295 PCM
Thanks, unfortunately not the culprit.....the search continues..... I have a feeling there's a bad trace I'm missing. Those leaky caps really did a number on this board.....
 
I figured some leakage would be the potential cause, I didn't see it in the first post though lol

give a closer look at U29 LM324 and U33 TL084 and 47 uf cap at C63. I don't know the structure of the sound board in that area by memory, but if there's traces on the top, remove the cap and continuity test the pads top and bottom to where C63 is installed. if you have an open you'll need to patch accordingly.
 
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