Help needed troubleshooting audio issue on A500+

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Jameson

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Hey guys, hope everyone had a wonderful Christmas!

I am putting the finishing touches on an A500+ system I just refurbed and in the final testing found a weird issue with the audio I have never come across before.

The LEFT channel is completely absent and the right channel is VERY quiet.

The board has been fully recapped and is running off a new PSU etc. EVERYTHING else is working perfectly which makes me think it cannot be the Paula (though I do have spares to test and will do shortly). I cannot see anything on the board that looks untoward and even though this A500+ did have some battery leakage in the past, it was very minor and there is no visible track damage etc at all.

I am wondering if it could be U14 - the quad op amp?

Anywho, as I said, never come across this particular issue before in literally dozens and dozens of Amiga refurbs, so am a bit lost as to where to start looking so I was hoping the symptoms might sound similar to someone who could give me a few suggestions.

EDIT - oh, one other thing I have noticed which might be connected - when the system boots the power LED is fully lit, but when a program changes the filter state and the power LED dims, it has a very slight flicker to it. Only slight, but it is there and I have never seen that behaviour from an Amiga before either. Could this be connected to the issue? Could the op amp (U14) be faulty and is causing both the audio issues and the slightly flickery LED when the filter state is changed?
 
The first thing I would be checking is the +12v and -12v audio power at R301 and R302 . If something is drawing too much current it will drop these significantly .
 
The first thing I would be checking is the +12v and -12v audio power at R301 and R302 . If something is drawing too much current it will drop these significantly .
Thanks mate - will check that shortly and post my results. I did check the relevant +12v and -12v pins on U14 and both were within 5% of what they should be, so I know the correct voltages are at least arriving at the op amp.

Will check R301 and R302 and update.
 
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