Yamaha CA-810 Missing R Channel

[ukfan4sure!]

Hey, I'm hoping someone will have the heart to give me a hand here. I recently (and finally) purchased a CA-810 that I've always wanted. Problem is, it's got a right channel out problem and I just wanted a little advice on how to figure this bugger out.

I've determined it's in the preamp. If I jumper in from another preamp, the main works fine. I had a suspicion it was the volume/balance knob as the balance is scratchy. Not sound scratchy, mechanically scratchy. I removed the 4-gang pot and it seems all of the potentiometers are doing their jobs. In measuring the center leg to each outside leg, I get expected resistances, and the expected resistance across each outside leg, the total R value of the pots. They are Balance: 5K, and Volume 200K.

So being of limited means (no O-scope), is there a way to find out where exactly I'm losing this signal? Can I use a multimeter to trace the analog through it on the right side? I'm going to tear it down and do a preliminary de-oxit, just in case I'm losing it through one of the switches.

Thanks!!

 

[avionic]

Exercise or clean the Input Select slide switch. These are best removed , disassembled and cleaned..

 

[MonkeyRelish]

A great way to test for audio signals is to get a cheap guitar amplifier. The cheaper the better.
Make an audio test lead out of a guitar lead by adding an 0.1uF capacitor inline.
Google “audio test lead” for a how to.
Plug the test lead into the guitar amp, and probe the signal path with a signal source connected.
You will be able to listen to the signal along the circuit, and find where it is missing.

Mr Relish

 

[ukfan4sure!]

A great way to test for audio signals is to get a cheap guitar amplifier. The cheaper the better.
Make an audio test lead out of a guitar lead by adding an 0.1uF capacitor inline.
Google “audio test lead” for a how to.
Plug the test lead into the guitar amp, and probe the signal path with a signal source connected.
You will be able to listen to the signal along the circuit, and find where it is missing.

Mr Relish

Interesting. Thanks!!

 

[mbz]

A great way to test for audio signals is to get a cheap guitar amplifier. The cheaper the better.

+1 on the audio probe. You can use any cheap amp/spkrs, even chip-amps on ebay. They also have "toy" oscilloscopes
which are some help for binary yes/no testing, much prefer my tektronix but it's still waiting a fix.

 

[thoresui]

Toy scope is pretty helpful and portable for basic troubleshooting you just need be aware of its limitations. There are multiple variants usually without power supply and 10x probes under 35 USD with shipping.