One Channel low and distorted - general question

[camgilbert]

Hello,

I have a luxman fq-990 which as the left channel and right channel amplification on separate boards that are interchangeable.

The right channel is working perfectly but the left channel is low and pops slightly as you turn the volume up.

The volume pot has a left and a right so balance is handled with that.

I swapped the two amplifier modules and the problem persisted on the left channel and through headphones.

Other then the volume pot and eq board is there any other place i should look to troubleshoot the issue?

Schematic online is very bad.

Many thanks in advance.

 

[slimecity]

I would be looking for a faulty small signal transistor in the pre-section.

Have you looked for the service manual? Find and download this.

First check your speaker fuses on the back and clean all controls with deoxit.

 

[camgilbert]

You sir, are amazing.
Was the transistors on the preamp board, replaced 2SC693's with KSC1845's.
All working great now.

Hope this helps someone else.

Cheers