Marantz 7t pre one channel much quieter

[tom1356]

I recently bought a 7t with a problem. The left channel is only audible with the volune at ~1 o'clock or higher. When only the bad channel has input connected, there is no output when in stereo mode. When the mode selector is on reverse stereo there is low sound. On the mono setting there is low sound. On the left setting there is low sound. Same results with the headphone jack.

To troubleshoot I reversed the wires going into and then out of the volume control and the problem stayed with the left channel.
I know very little about solid state equipment.
Any suggestions on where to look for the problem?
Thanks
Tom

[bully]

The first thing let's do is clean those controls and switches with DeoxIt followed by ProGold lube, both Caig products and should be available at a dear price, at Radio Shack.
Lots of good cleaning advice here if you use the search function.
Clean those pots and switches then revisit your problem.

[Nakdoc]

While it could be in the output stage after the volume control, I suspect the volume control has a broken wafer. Jumper the middle (wiper) leads together. If you get equal volume, then the control itself is bad.

[tom1356]

I cleaned all the switches/controls. I tried to short the center taps on the volume control and it made an awful hum/distortion.
Same problem.

[Nakdoc]

Too long a wire? Try something shorter. That shouldn't have happened.

[tom1356]

Too long a wire? Try something shorter. That shouldn't have happened.
I think it's strange that the wire going to the two center taps, from the boards, is uninsulated.
I used a 1" piece of silver wire to short them.
Thanks for the help.

[Nakdoc]

Hmmm??
Anyone have any ideas?
Since the wires are easy to get to, you could cross connect them. That would test the output stage. If the other channel has the problem, then the pot is bad. Same channel, the output stage is broken.