Amp making popping sounds and noise?

[67Mopar]

I ordered Nichicon VY... Are those okay?

[guitardude57]

Good eye Jana!
I'm getting out the door, and didn't look real hard at the pix... went off of descriptions of the problem...
Cya all later...

[NickC]

I ordered Nichicon VY... Are those okay?

Others may feel differently, but I've used Nichicon's and think very highly of them.

[67Mopar]

I'm looking at the second photo. The tube socket in the middle sort of to the left (a 9 pin socket). There is a wire going across the socket to bridge two pins. Is that wire touching the center shield pin thing? If so, and if it's not soldered to that pin, I would highly suspect that as a source of noise and pops.

The wire is not touching the center post. Solder is good.

[Structo]

Pictures?

Isn't 67 Mopar someone we know?

What amp is this?

[67Mopar]

Okay... I've replaced the preamp filter caps and touched-up the solder joints, but the noise still exists. I took a reading at the heaters, and my Fluke meter is reading 3.2VAC! The schematics read 6.3VAC...

[guitardude57]

where are you reading from? Sounds like one leg measured to ground?

[67Mopar]

I touched one leg (-) to chassis, and one (+) leg to the heater terminal(s).

[guitardude57]

You will get about 3.2 or so, between ground and pins 4/5, and also pin 9 and ground... on a 12ax7 type. Gives you 6.3 together... give or take.

[guitardude57]

Any way of recording the noise? May help.

[67Mopar]

I thought it was suppose to be 12.6 volts combined?

[guitardude57]

In series... yes. 12 volts AC or DC
Parallel 6.3 VDC

[guitardude57]

What amp circuit is this?

[67Mopar]

Got it! Reading 6.3 between pins 4/5 and 9.

[67Mopar]

What amp circuit is this?

Cornford RK100

It's a sort-of a white noise with random popping. Like a cold-joint, or maybe a failed capacitor maybe? There's a JFET in the circuit, and I'm suspecting it may be the culprit. I replaced all of the sockets with NOS McMurdo's, and I know those are good. If I bypass the effects loop, the noise is not audible. Rather, if I plug into the effects return, the noise is very faint - nearly inaudible. If V1 is 1st and 2nd stage gain, then V2 is 3rd stage gain and cathode follower. V3 is effects and 4th stage gain. V4 is PI. If I remove V2, the noise stops - but so does the entire signal...