Amiga 500 sound problem on one channel - newbie

Hi guys. I have been resurrecting my Amiga 500. I am completely new to the hardware side of things. So far I've fixed the floppy drive, and replaced the keyboard as controller was dead. All seems to be working except the sound on one channel n I hope my description will give you an idea of what is going on.

On the channel that is not working, I can hear the audio very faint, but there is an audible deep electrical hum noise also present (not like a bad contact type of noise, if that makes sense).

Also when I plug both phono leads into the Amiga, the signal from the working channel is coming out of both speakers ?; (not panned left or right but just straight mono, and still missing the dead left channel)

Hope this makes sense. Feedback much appreciated

[Amiga1992]

Hmm maybe bad audio capacitors? It would be my best guess. That the 2 cables also aren't recognized may hint to a bit more problems too.

Also it could be some issue with the -12V line of the power supply. have you tried with another power supply?

[Daedalus]

This may sound odd, but are you sure the audio cable is ok? Just to rule out something like a bad ground on one side of the cable. Usually the power supply will affect both channels together so I wouldn't worry about that if one side appears to be working fine, but a dead capacitor could be a good call. It could also be a bad op-amp, or any of the op-amp related components. I'd look for damage around there, and if you have the capability, check for continuity in the area against the schematics, then the components.

[demolition]

My guess would be a loose RCA connector due to the solder breaking. I have seen several A500s which required resoldering of the RCA connectors as they tend to become loose after having wiggled cables in and out of them 100s of times. The side-by-side motion that is normally applied will break them eventially.

With a connector inserted, you should easily be able to feel if it can move a bit or if it is solid.

The audio caps usually don't go bad in a 500. It is not a 500+ by any chance? In that case, a leaking battery could have caused all sorts of trouble. It could also happen in a 500 with the battery from a trapdoor expansion although the distance is greater so the damage is usually limited to just the expansion board.

Hey guys. Thanjs for the suggestions. Tried another phono lead, different amp but same result.
The phono plugs seen fine, I moved them about but nothing changed.

Earlier I tried it again and as soon as I turned off the power, the music came to full. volume for a split second..

I've tried the PSU on another Amiga 500 and that is working perfectly (full sound etc)
Does anyone know of anyone who could fix the issue (I'm in West Midlands UK). I did see a company online that does repair. I wouldn't feel comfortable doing the soldering etc. Wish I was an electrician!