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JVC A-GX3 Volume spikes sometimes

S

Spoorick

New Member
Hey guys,

I've got a question about my vintage JVC A-GX3 stereo amplifier. I bought it about 2 years ago and it was supposed to be refurbished and cleaned. This wasn't the case since the right channel has a tendency to suddenly become much louder.

I've cleaned the sliding potmeters for volume, balance, low and high frequencies with 99.9% isopropyl alcohol. This resulted in a better signal for both speakers but the right speaker still has the previously mentioned issue.
Tapping on the amp can help with the issue but so does pressing on the potmeters. This is confusing for me since it actually doesn't tell me where the problem is coming fro. I am kinda wondering what is causing it and I am at a loss for information. People generally don't know or use this amp and don't wanna service it. Anyone with good advice for me or tips I should look into?

Cheers!
 
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Welcome to AK!

I would use Deoxit's Fader Lube on those slide pots. Straight alcohol would remove the lubrication causing rapid wear. You may need another cleaning paying special attention to the volume and balance pots, If that doesn't resolve it, check for cold solder joints where the pots are soldered to the PCB.
 
redk9258 said:
Welcome to AK!

I would use Deoxit's Fader Lube on those slide pots. Straight alcohol would remove the lubrication causing rapid wear. You may need another cleaning paying special attention to the volume and balance pots, If that doesn't resolve it, check for cold solder joints where the pots are soldered to the PCB.
Click to expand...

Yeah I bought the fader lube grease for the sliders. I hardly touched the sliders after they were cleaned so they should not have worn too much from that.
Any tips on how to check if the solder is still ok?
 
Look up cold solder joint on Google and look at pictures or videos. Where the sliders are soldered to the PCB, the solder should be shiny. If it is dull or has a circular crack / mark, it is suspect.
 
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