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Vintage Denon amp output on 0 volume?

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PhrogHospice

New Member
Alright so apologies if this is not the correct place to post this as I'm yet to get my head around this site...
I got my hands on a Denon PMA-320 integrated amp (circa 1989) today and have spent a couple of hours troubleshooting an unusual output issue: when the volume is at 0 there is still sound from the left channel- quite loud actually, and the right channel doesn't even kick in at all until it's turned up to about 1/3 vol. Ruled out speakers and connections. Initially I assumed it was just a case of very dirty pots as there was also the typical touch of graininess when adjusting bass/treble/balance/vol but since I have thoroughly cleaned them the graininess has cleared but the output issue remains.
So I did some digging in old threads and discussions and concluded it could be the relay, desoldered & disassembled to properly clean the contacts and upon seeing them completely blackened I thought that must certainly be the cause buuut no, the issue remains with no improvement. Board looks good with no cold solders so all I can really think of is that perhaps the volume pot is faulty and needs replacing. I will add that this amp actually does sound fine when turned up to where the right channel kicks in at which point the output is even. This unit has one of those ribbon swiper? selector switches where there's a "tape" going from the control to a module on the board so there's also the possibility that is a culprit however it does not appear to be serviceable/can't see how it could be opened.
Any suggestions appreciated!
 
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Are you able to access the insides of the volume control? Sometimes squirting some DeoxIT D-5 inside the control, and then working the control through it's range of motion back and forth (roughly 20x-50x) times may clean it and get it to work properly. Hopefully it's as simple as that.
You may also use the same DeoxIT cleaning process I mentioned for the volume control and do the same for every switch and control. It might help with your issues.
 
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Tape monitor loops are common causes of channel dropouts, but not the additional sound.

Have you measured the volume pot out of circuit?
 
eiraved said:
Are you able to access the insides of the volume control? Sometimes squirting some DeoxIT D-5 inside the control, and then working the control through it's range of motion back and forth (roughly 20x-50x) times may clean it and get it to work properly. Hopefully it's as simple as that.
You may also use the same DeoxIT cleaning process I mentioned for the volume control and do the same for every switch and control. It might help with your issues.
Click to expand...
That's the first thing I did (all switches and pots).
 
I'm not a tech in any way shape or form.
Just wanted to share a personal experience.
I had a Marantz 1060 integrated and it had the exact same issue.
Took it into a tech and he had to replace the volume pot,problem solved.
 
if its not the volume pot itself, a cracked solder joint on the ground end of the pot will do this too. Ohm check and eyeballs will generally tell you. Ohm from a good ground to the pin on the pot and verify 0 ohms. Ohm check from ground to center wiper and confirm its also essentially 0 at min volume and the value increases as its turned up. Any appreciable amount of resistance from ground to wiper if the grounded pin is good means the pot is bad. Or at least needs significantly more cleaning but I wouldn't hold my breath on that point.
 
PhrogHospice said:
Alright so apologies if this is not the correct place to post this as I'm yet to get my head around this site...
I got my hands on a Denon PMA-320 integrated amp (circa 1989) today and have spent a couple of hours troubleshooting an unusual output issue: when the volume is at 0 there is still sound from the left channel- quite loud actually, and the right channel doesn't even kick in at all until it's turned up to about 1/3 vol.
Click to expand...
Just to be sure, does this happen with all input sources? CD, turntable, etc.

Thanks!
 
gadget73 said:
if its not the volume pot itself, a cracked solder joint on the ground end of the pot will do this too. Ohm check and eyeballs will generally tell you. Ohm from a good ground to the pin on the pot and verify 0 ohms. Ohm check from ground to center wiper and confirm its also essentially 0 at min volume and the value increases as its turned up. Any appreciable amount of resistance from ground to wiper if the grounded pin is good means the pot is bad. Or at least needs significantly more cleaning but I wouldn't hold my breath on that point.
Click to expand...
I actually don't own any testing equipment, just going by process of elimination I'm fairly sure the volume pot is the problem but I suppose that could only be verified by testing. I don't plan to get fully into repairs but do as much troubleshooting as I am able to before handing units over to my tech. All solder points look healthy.
 
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