Right channel noisy. Help troubleshooting

[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.

 

[denti alligator]

Again, I’m giving up. I can’t see where this is coming from. If I jab every single terminal, plus some of the wires, plus some of the resistors and capacitors and it makes no difference; if I re-flow almost every connection and the right side and it makes no difference; I don’t see what else to do. I guess I could switch out the sockets for the 2A3 tubes and see if it changes channels. I’m getting to the point of frustration—and also totally bummed to be throwing a small NYE party with no music.

 

[denti alligator]

Happy New Year!

I’ve got my PayPal invoice to send this to you, Paul, but want to give you a chance to weigh in one last time after hearing the recording (posted on previous page). Let me know if there’s any last-minute tests you think might help locate the source of this problem. Otherwise, I’ll pay the invoice and initiate the repair shipment. Thanks!

 

[Paul Birkeland]

I still believe it's a loose connection with the realistic possibility that when it gets here it makes no noise in my workshop.

 

[denti alligator]

And most likely it is, but damned if I can’t locate it. Would you suggest trying to swop out the tube sockets? If the noise moves channels, we’d at least know it’s something there.

 

[Paul Birkeland]

I think if you tried to remove the tube sockets, you'd probably damage one in the process to the point where it would no longer be useful, so you'd be worse off than you are now.

 

[denti alligator]

Too late, unfortunately. And I have to say, the socket on the right doesn’t look good. One of the pins drops down into the socket all the way. The other socket looks good. I’ve done the desoldering and hardware exchange. I’ll resolder
after dinner and report back. If the noise moves channels I might as well start by replacing the socket.

 

[denti alligator]

That was a bunch of work for nothing!  Switched out the sockets and the noise is still in the same right channel.

There’s no way you won’t hear this, Paul. I’m very curious to know the source and am very happy for your help on the way and your repair expertise!

Thank you. I’m paying for the shipping box now.

 

[Paul Birkeland]

I appreciate your willingness to spend some time on your end before sending it out.

 

[denti alligator]

I’m very grateful for your patience troubleshooting with me, especially during the holiday week.

 

[Paul Birkeland]

I finally had some bench time to explore this repair.  The noise was absolutely there, so Denti isn't crazy.  I ended up shorting stages to chase the noise and it was present even with the 2A3 grid shorted on the channel, so that localized it to a very specific spot.  When I was looking around there, I noticed this crazy green corrosion on the tube socket, and I could poke around with my meter and measure some substantial DC voltage crawling around on the surface of the ceramic, so out that went and in went a new tube socket and all is well.