SX-750 Aux input dead in one channel

[Water]

Just picked up a Pioneer SX-750 on CL. It is my first vintage receiver (previously using a mid-80s Sony). Seems to be working great on FM, Phono, and Tape 1. All of those work fine in both channels. For some reason the left channel on the aux input seems to be dead. Any thoughts? Also is there any difference between Aux and Tape 1 / 2?

edit: Just tested Tape 2, that also works fine on both channels. So its just the aux input that seems to be messed up.

 

[Water]

Strangely it seems to work on Aux now too. Very weird considering I tried two different sources before on Aux with two different cables and both had an issue in the left channel. Tried my CD player again on Aux and was hearing it great through both channels.

 

[Nortonrider]

Start with a good cleaning--sounds like your controls need some Caig Deoxit5 and Faderlube. If problems persist after cleaning, post the symptoms.

 

[markthefixer]

Strangely it seems to work on Aux now too. Very weird considering I tried two different sources before on Aux with two different cables and both had an issue in the left channel. Tried my CD player again on Aux and was hearing it great through both channels.

LOOK at the label for aux: It says: AUX/MIC...

The aux input goes THROUGH the mic jack!!

If a mic is plugged in, the aux is interrupted, the mic signal is sent through IT'S OWN PERSONAL LITTLE AMPLIFIER CIRCUIT, and then that amplifier's output is sent to the jack and substituted for the aux signal.

Thus bad or intermittent contacts at the mic jack WILL give you erratic mic and aux connections. And iirc it's a pita to clean. It really cannot be disassembled for cleaning and is a rather unique jack.