Enough to drive you nuts!

[bluesguitar]

I've been tracking down the source of a rustling static in a '67 Super Reverb for a couple of months. Finally, after re-soldering the eyelet of the # 2 pin (grid) of the PI the rustling stopped, and all appeared fixed. I have no idea why, because I replaced that 1M resistor and took care in my soldering. Now, three weeks later it is acting up again. Sure enough, re-soldering that eyelet makes a difference. However not always for the better. Sometimes I can't get a sound out of the amp. I've learned that this PI circuit will give me every symptom of a bad OT- loss of volume, lots of static, and eventually cutting out completely. So I suck the solder out, and try it again. But now it has a lack of bass, or no sound at all. Finally, I sucked the solder out and left it that way. There is just enough residue of solder on the leads that they are stuck on the eyelet, but the eyelet has no solder in it. Beautiful tone, as if there was never a problem. Of course, I figure it is only a matter of time until it starts acting up again. Why would this eyelet be giving me so many problems? There are only three leads connecting and I have replaced the two components, and re-tensioned the tube socket. So, other than a possible bad tube socket I have run out of explanations. For those of you who fix amps for a living what tests would you do in such a situation to come up with a definitive diagnosis and fix?

[beasleybodyshop]

Could be that the circuit board is going conductive?

Have you tried chopsticking your solder joints to see which area is acting up?

[ampgeek]

Maybe something going on at the backside of the board? A thread of solder creeping to other wires/eyelets or legs of the new 1M a tad long and lightly touching the chassis?

Just thinking out loud!

Good luck,
Dave O.

[Phil_S]

Conductive board or a whisker of solder or wire. See if you can simply put the stuff for that eyelet up in the air and rest it on something non-conductive like a bit of rubber glued over the eyelet. Eliminating the eyelet as a point of contact seems to be what's needed.

[jjman]

I had the same problem on the 5-way junction eyelet to the grid of the 3rd preamp stage on my DR. I lifted the connection using a terminal mounted via the board's nearby screw.