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YesAffinity

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I've had this CPS-2 'A' Board for many years. Got a pretty decent deal on it - complete SF Alpha set in CPS2 box. The 'A' board had very low audio on the left RCA output. The problem existed with the board set to mono or Q-Sound output. I've always set it to mono, and just played with audio coming off the JAMMA edge, up until putting an HDMI kit on it, which of course sources the audio well ahead of whatever was causing the issue.

....but, I'm OCD, for one. And, for two, there's always the potential to run the board with the analog audio outputting, and well that CPS-2 stereo Q-Sound is just so so sweet.

So, got a bee in my bonnet to track down the problem. Started with tracking the circuit back through mostly benign components - caps and LM833's. I pulled all caps and checked them - no issues. Reflowed a bunch of solder joints in the whole audio section just for good measure.

Re-tested on a whim and a prayer - no improvement.

So, kept going on the circuit, and arrived at a couple companion IC's - a TC9176P and a TC9185P. And what are their purpose? Audio attenuation and balance. Pulled the TC9176P, replaced it and re-tested. No improvement. Replaced the TC9185P - FIXED!

Not only is audio level balanced, but there is improvement to overall volume, as well.
 
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pcitures?> i have a similar issue with one of my boards
 
I didnt take pics of the board before buttoning it up, but this is the faulty chip. The two ic's are near the audio amp and in close proximity to each other. They are clearly labeled with the part numbers I noted.

And well, I did take a picture of the output levels through my stereo mixer after repair. Before repair, the left channel was at 1 bar next to the right channel's 4 bars.
 

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