Stereotech 1200 Channel Issues

[BSharp]

Hey AK,

been lurking here for a while because it seems all you people are my kinda people.

I’ve become the owner of a Stereotech 1200 in decently nice condition. All inputs and outputs work, sounds immaculate, and is a lot better than the Pioneer VSX that I previously used as a receiver. On top of all this, the wife loves it because of the wood paneling on the sides, so in her opinion it looks great and sounds great.

Here’s the rub: I’ve discovered that my left channel (while using either Aux 1 or Aux 2) gets weak and crackly after power on. I haven’t noticed this issue on the phono inputs, only on aux 1 and 2.
I’ve used deoxit (the 100% stuff) on the input selector, volume pot, speaker outs, input jacks, pre-amp jumper, and spent maybe an hour just rolling those dials and switches back and forth.

I then sprayed those areas with the 5% deoxit to hopefully blast away the corrosion that would be worked loose from the 100% a little more but still keep the contacts conditioned.

I am fairly certain there isn’t a bias offset, and I’m also certain that this doesn’t have to do with the contacts related to the switches or the dials on the front.

I guess I’m asking if I should look for solder points first or if I should just start attacking resistors and such with my multimeter and see if anything pops up throughout that signal chain for the aux inputs.

I’m hoping there’s some stereotech wizard out there to point me in the right direction or someone who has encountered this issue on recievers/amps in the past and fixed it multiple times and could help me find the path forward.

I can’t imagine fixing this issue will be as stressful as fixing the Nakamichi Dragon CT I just refurbished for a guy but now that I’ve said it, I’ve probably jinxed myself.

 

[Binkman]

Welcome to A.K
throwing darts here...The selector switch may need more contact cleaner and inspecting for aged solder joints is always a potential. The service manual shows a pc board for Aux 1&2.. could trace that back.
Readers comment was in high regard for this unit and worth a read. Good manual, too
https://www.hifiengine.com/manual_library/stereotech/1200.shtml

 

[BSharp]

Thank you for your response Binkman.

I cruised through the service manual and I just want to be sure what I'm looking at is the right thing.

Firstly, I will definitely give the input selector a good dose of Deoxit again. I was pretty thorough before targeting each individual ring of contacts but maybe I ended up missing a point of contact as there are A LOT of contact points on that thing.
I'll probably also trace the left channel in the AUX section to make sure the resistors are good in that line.

Secondly,
Would it be a bad thing to just reflow the solder joints in the Aux line on the PCBs or is that bad-juju and I should prepare myself to remove all the old solder and doing new solder joints for the whole board?

Last question: attached is a snippet of the manual, highlighted in yellow up to the weird sickle thing. Am I safe to assume that the sickle-shape is the ring of contacts on the input selector dial?
It looks pretty dang similar to the contacts I was cleaning the other night, but I just want to be certain that it isn't some sort of Illuminati shenanigans that is on a whole other level than I am prepared to deal with.

 

[Binkman]

Would it be a bad thing to just reflow the solder joints

Use a little flux to reflow. might post a pic of the component side of the pcb to show whats installed.

Yes the C shape snippet is the selector switch.