AV receiver--speaker gets loud then quiet

[jamisonia]

Hey I'm not sure if this is where I'm supposed to post this, but there didn't seem to be a more logical place.

I have an old receiver from Wal-Mart that I'm wanting to use with a tube TV and some retro video game consoles, like Nintendo and Sega, just in lieu of the TV speakers. I figure anything should sound better than those.

So I pulled out my old receiver, and hooked up the front 2 channel speakers to fine out that the Front Right one does something very odd. As I increase the volume it gets lower, then after one particular notch in volume it gets very quiet again. It continues to get louder as I increase the volume, but it never gets louder than it was before it started being quiet, and it's much lower than the Front Left Speaker. Its very distracting. I opened it up, and I couldn't find anything obviously wrong.

I tried switching the speakers and it was the same story, so its not the speaker.

Any ideas whats wrong?

 

[TLS Guy]

Hey I'm not sure if this is where I'm supposed to post this, but there didn't seem to be a more logical place.

I have an old receiver from Wal-Mart that I'm wanting to use with a tube TV and some retro video game consoles, like Nintendo and Sega, just in lieu of the TV speakers. I figure anything should sound better than those.

So I pulled out my old receiver, and hooked up the front 2 channel speakers to fine out that the Front Right one does something very odd. As I increase the volume it gets lower, then after one particular notch in volume it gets very quiet again. It continues to get louder as I increase the volume, but it never gets louder than it was before it started being quiet, and it's much lower than the Front Left Speaker. Its very distracting. I opened it up, and I couldn't find anything obviously wrong.

I tried switching the speakers and it was the same story, so its not the speaker.

Any ideas whats wrong?

No idea. If you have no test gear, then I would recycle it. It won't be worth taking to a service center.

I would start by looking at supply voltages to that channel as I increased the power demand driving it from an audio oscillator.

Then put both channels on the oscillator and check each voltage gain stage with a dual channel scope to see at what point signal level dropped. Then I would analyse that part of the circuit with the reduced gain.

 

[KEW]

As I increase the volume it gets lower, then after one particular notch in volume it gets very quiet again. It continues to get louder as I increase the volume, but it never gets louder than it was before it started being quiet, and it's much lower than the Front Left Speaker. Its very distracting. I opened it up, and I couldn't find anything obviously wrong.

Do you hear any scratchy sounds as you change the volume knob?
If so, you can clean the volume knob. Just go to RadioShack and they will sell you cleaner and tell you how to use it.
Otherwise, you are probably best off to simply toss it as TLS Guy suggests.

 

[TLS Guy]

Do you hear any scratchy sounds as you change the volume knob?
If so, you can clean the volume knob. Just go to RadioShack and they will sell you cleaner and tell you how to use it.
Otherwise, you are probably best off to simply toss it as TLS Guy suggests.

If that is an AV receiver, that will be new enough to have a solid state volume control, not an old fashioned slider and carbon resistor. The latter have not been used for years now and are getting very hard to get for vintage restoration. I think he would be wasting his time with tuner cleaner.