Right channel noisy. Help troubleshooting

[Thermioniclife]

You said you replaced the tubes, did you replace all tubes or just the 2a3's?
My money is still on the 12at7 on the offending side. a thorough cleaning / scraping of the pins and socket may help.

[Paul Birkeland]

Last time I turned it on the scratchiness started before the LEDs lit up. Not sure if that tells you anything.

That tells me it's most likely that your issue is in the power supply and/or output stage, so 4 pin sockets and power supply wiring, not the C4S boards and 9 pin sockets.

[denti alligator]

That tells me it's most likely that your issue is in the power supply and/or output stage, so 4 pin sockets and power supply wiring, not the C4S boards and 9 pin sockets.

OK, I’ll go and reflow those. Which are the main terminals for the power supply on the right channel?

I replaced the 12AT7s. The 2a3s are not an issue I don’t think. At the least, when I switch them the scratchiness stays in the right channel.

[Thermioniclife]

The SM2 uses a pseudo dual power supply, check/reflow the 130 ohm resistors and the 100uf caps on the offending side and also the connections where it connects to B+

[denti alligator]

I reflowed and added a little solder to the right side 4-pins and terminals connected to it and to the terminals where the 100uF caps are and to the tabs on the chokes.

Turned it on: scratchy.

[denti alligator]

I think I’m ready to send this in. Paul, can you tell me which terminals I should reflow besides the 4 pins, and I’ll try one more time. If that doesn’t do it, I think I’ll let you take over.

I decided to tighten the socket brackets on the 4-pin R. This has significantly reduced the amount of scratchiness. I’m getting a short pop here and there, at most. So these pins are clearly the culprit. I had already reflowed them carefully. The 2a3 was a bit too easily wobbled in place, hence the idea. Now, granted, the L side is about the same (in terms of looseness). And again, I’m still hearing a little scratch or pop every 30 seconds or so. Aaaand, as I write it’s starting to make the noise again steadily…. So never mind!!

… aaaaand now it’s quiet again, with the occasional scratch/pop. So annoying. I’ve done nothing in the meantime but sit here. I’m not even playing music.

(And if it is these pins, why wouldn’t I get a reaction from gently rocking the tube in place while turned on, which I tried?)

[Paul Birkeland]

You could try a replacement socket.  If there's any possibility that the fat pins were ever inserted into the wrong holes, or even just attempted for that matter, that can stretch things out a bit.

Otherwise just follow all the wiring that leaves the 4 pin socket to the 12 or to terminals closest to those sockets and reflow those joints. 

[denti alligator]

It was pretty quiet for about an hour, then I left the house. I’ll test it again tomorrow. I don’t think I ever put the tube in wrong. I’ll report back. Do you think replacing the socket is the way to go?

[Paul Birkeland]

If you wiggle the 2A3 around in that channel and hear the noise, I would either replace the socket or be sure that both ends of everything connected to each socket pin is well connected.

[denti alligator]

Well, maybe it’s not those pins after all. I woke up this morning, flipped on the amp, and the scratchiness started worse than ever. Moving the tube in the socket *does not* affect the noise. There is zero connection. Sometimes I wiggle the tube and it’s totally quiet. Sometimes it makes noise when I’m not touching it.

I cleaned the socket with Deoxit again. Nothing. But now as I’m writing it has stopped. Maybe warming up has an effect on it?

Nah, it just started again. If I didn’t know better, I’d say this is interference from a wireless signal or something. It’s so erratic.

At this point I think I’ll contact Eileen and get it sent out to you. Not sure what else to do.

P.S. Yeah, I’m done. If anything, it’s gotten worse. I tried tightening the sockets again. No difference. I’m very curious what you find, Paul! Coming your way soon.

[Paul Birkeland]

Can you post a recording of the noise? 

[denti alligator]

Can you post a recording of the noise?

Sure. Gimme a minute or two.

[denti alligator]

Here is about 1:30 from the moment I turned on the amp.

https://www.dropbox.com/s/swy8l1cuzyluszc/New%20Recording.m4a?dl=0

Just so you know: I left the amp on and it’s quiet now. Won’t last more than 30 seconds, though.

[Doc B.]

Hum balance pot, maybe?

[denti alligator]

Hum balance pot, maybe?

I reflowed the connections there and have adjusted it to see if it has any effect. None.