Yamaha Ca-2010 Relay Ticking Issue

If power supply voltages and relay coil voltages check out, I would start investigating the preamp - specifically what Yamaha schematic calls TONE CONTROL BOARD.

I'm looking at a CA-1010 schematic - but the 2010 is similar. The volume control is a somewhat complicated arrangement that, honestly, I've never really bothered to figure it out completely. The volume control has 4 potentiometers. Two are ahead of the tone board and two are after the tone board.

If the tone board is passing DC it MIGHT be increased or decreased by the volume control. (i.e., increasing the volume increases DC that is passed to the amplifier and triggers the protection circuit)

This is shotgunning it a bit, but at close to 40 years old, it's due. Check all solder connections on the tone board, replace all electrolytic capacitors, and replace VD1212 and HV46R "double diodes" with two 1N4148 diodes in series.
 
Well if I have the right pins the voltage starts at 1.5v when the relay is clicked on and it does slowly drop after it clicks off.
 
Check the voltage on the coil of the relay. I've seen many regulators go bad that are feeding power to the relay itself and they will present the symptoms your seeing. Leave your meter on the coil and increase the volume to see if you get a drop when the relay opens.
Well if I have the right pins the voltage starts at 1.5v when the relay is clicked on and it does slowly drop after it clicks off.

How about when you vary the volume control?
 
Alright, so this amp isn't being very consistent. Before when I first tested it after putting in new caps it would only click off if I increased the volume and it would stay off. Then after awhile it went back to ticking like it was before but now it will tick on and off every few seconds even if I have the volume all the way down.

As for voltages I have not tested to see if the preamp is outputting DC but I have tested the power supply voltages and they seem OK but I'm not sure if I'm looking at the schematics wrong but I can't find what voltages they should be.
 
Here's an update-

So I don't think it's the preamp since it is not outputting DC and the problem continues even after disconnecting it with the switch in the back. Now I'm back at looking at the power supply. Went through and checked every transistor and found two c1775 transistors to be faulty. Does anyone know where I can find replacements or equivalents?
 
HI there, I think I may be having the same issue with my CA-2010. Were the burnt out diodes and faulty transistor the only things wrong with your unit? Also when it was acting up, was your headphone out fine?
-Hope you're enjoying your unit!
 
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