Pioneer sx-450 left channel won't mute with volume-knob.

Hi guys,

I got a Pioneer sx-450 from a thrift store, it was in bad shape, but I got kinda far by cleaning the dust out and use deoxit. Tuner section works good now, and all functions work, but it has a problem with the Right channel.

The right channel doesn't get muted with the volume is turned down. It keeps playing fairly loud as well. (not distorted)
The volume in the right channel appears to be fixed, til the moment L and R are equal, then both channels can be increased/decreased simultaneously.
(Balance knob works fine too)

Any help?

I did rewrite my original post, because I thought the balance knob wasn't working. But the balance knob seems fine, and it's the right channel that doesn't get muted (not the left channel.
The right channel keeps playing with volume turned all the way down.

(Balance knob works fine too)

Click to expand...

So when you turn the balance all the way left, the right channel does get muted?

princever said:

So when you turn the balance all the way left, the right channel does get muted?

Click to expand...

Yes.
The way I see it, the balance mode seems to working like it should.
Turning left will mute the right channel.
Turning right will mute the left channel.
(note: because the right channel doesn't mute properly I had to troubleshoot this with one speaker at a time)

So, basically, when the balance is centered, the right channel keeps playing when the master volume is set to 0.

check the soldering at the vol pot

this section of the circuit is very simple. I have, however seen a defective volume pot which was shattered in one channel produce a similar symptom. But you should be able to check the function of the potentiometer with a meter, even if it must be desoldered first for accurate readings.

imo the volume pot wafer has lost the connection to ground, near the ground, if it was lost further up in rotation there would be a place in the rotation where the sound disappears.

I had something very similar happen to me on a SX-3800.

ACV-161 100k ohms, loudness tapped. unknown number of detents

unfortunately you will have to pull the front panel, and probably the front of the chassis to unsolder the volume control to test and replace it.

The donor list (parts.pioneerelectronics.com):
sx-450, sx-550,
sx-580, sx-680, sx-780, sx-790, sx-880, sx-890