A buzz in both channels

[Skipperrik]

I checked the resistors. The B side measures 2.44KΩ but the A side measures 7.4KΩ. That's bizarre!

How do you check a regulator?

[Paul Birkeland]

I think I'd start by replacing the regulator resistor on that funky side. 

[Skipperrik]

Okay. I’ll order one and let you know the results.

Thanks for your help, Paul. I really appreciate it.

[Skipperrik]

I received a couple of new 2.49KΩ 1/4w resistors. I measured one of the new ones prior to installation and it measured 2.48KΩ. After removing the original one and installing the new one it measured 7.5KΩ, just like the original one did.

What could be causing this?

[Paul Birkeland]

Are you measuring the resistor with your meter across the resistor itself while it's soldered into the circuit?  Did you measure the ones you took out?

[Skipperrik]

Yes, I measured it before inserting it (2.48KΩ) and in place (7.5KΩ). The one I pulled out measures 2.4KΩ.

The resistor on the B side measures 2.44KΩ in place. Something is different on the A side.

[Paul Birkeland]

Pull the 431 regulator on that side and measure again.

[Skipperrik]

It's still 7.5KΩ.

[Paul Birkeland]

I'd post some pictures of your board, something is definitely not right...

[Skipperrik]

The regulator is still out. I may have to replace it. On the underside, the red wire on the left broke while removing it so it will have to be replaced.

[Skipperrik]

Just to clarify something, in the photo of the underside of the board the black wire appears to be connected to the Kreg terminal. I had to disconnect it from the -reg terminal to remove the capacitor and it only appears to be connected at Kreg. It was connected correctly before I removed the capacitor.

Just for the heck of it I measured the resistance across the capacitors. I don’t know if this helps but here are the values:

A side (the problem side)
0.1uf 400V = 146
2.2uf 250V = 145.8

B side
0.1uf 400V = 34.2
2.2uf 250V = 35.4

That’s a pretty big difference so it should be an indication of something.

[Paul Birkeland]

I have no idea how the measurement of the 2.49K resistor is increased by installing it in the circuit.  Something is definitely amiss, but I have no idea what that is.  Did you end up replacing the 431 regulators? 

[Skipperrik]

I don’t have a replacement but the value is the same whether it’s in the circuit or out. I could swap the one from the good side if you think it would help but that’s a lot of trouble.

[Skipperrik]

I have a very embarrassed look on my face. I pulled the transistor out previously, not the regulator. I just pulled the regulator out and the wayward resistor now reads 2.48K ohms. I guess the regulator was allowing current to be sucked out of the leads of my ohm meter.

[Skipperrik]

I need to replace the transistor. Mouser has two, an MJE350 and an MJE350G. The G looks like the one that is used but I want to make sure it's the correct one since the specs differ. Should I order the 350 or the 350G?
https://www.mouser.com/c/?q=MJE350

Is this the correct regulator?
https://www.mouser.com/ProductDetail/926-LM431ACZ-LFT3