Restoration for Yamaha C-4 preamplifier + Sherwood s-8900A.

[In The 21st Century]

I have a Yamaha C-4 preamp. The problem is that, when you power it up it does nothing. And to add to that, I am seeking a ground up recap and restoration on this unit with good quality components. I also have a Sherwood S-8900A receiver that works, but also needs a complete overhaul. Is there anyone that can help me? If so, please let me know. I would be very grateful for their help.
Sincerely, In The 21st Century.

 

[rayma]

Do you want someone local to do that work for you, or just give advice?
If you don't have the service manuals, that's what you should get first.
Yamaha C-4 Natural Sound Stereo Control Amplifier Manual | HiFi Engine
Sherwood S-8900A Stereo/Dynaquad Receiver Manual | HiFi Engine

For the Sherwood, try cleaning all the pots and switches before changing
any parts. Sometimes things will work great just by doing that,
depending on how it was used, and the environment it was in.

This also applies to the Yamaha. It has an output muting relay, so that could be bad.
CAIG D5S-6-LMH DeoxIT Spray 5 oz. Original Can

 

[Tomom]

I am currently restoring my Pioneer TX-8100 tuner. Initially also had problem with a very weak output, almost silent. Traced it to a faulty mute circuit, faulty capacitor.