Interference, smoking potentiometer

[Swollazn]

Hey all, not sure how to diagnose this but the crack randomly has loud paper crumbling sounds. Also, I notice this happening also when I physically move the crack around (tapping the crack, fiddling with the headphone jack). I wonder if this means that I have a short somewhere?

And while reflowing the solder, I noticed the potentiometer smoking at one point. I've kept a good eye on it and it hasn't happened since. But the cause of most problems is whenever the potentiometer has slight movement. I keep the crack on its side now since it happens much less like that.

Should I replace my potentiometer or resolder something else?

[Paul Birkeland]

Can you post some build photos and your DC voltages?

The potentiometer handles no DC current, so if it is getting hot and emitting smoke, there will be something very, very wrong with your voltage checks.

Also what kind of flux/solder did you use on your build?

[Swollazn]

1 65V
2 179v
3 1V
4 178v
5 83v
6 1v
7 100v
9 111v
oa 64
ob 82
g 1v
b+ 178
ia 180v
b/ab 0
ib 178

b3 b6 no resistance (very strange), fuse still intact.

Using kester 44 rosin core.

https://imgur.com/a/ydwN5IN

[Paul Birkeland]

Were these problems present before you installed the Speedball?

[Swollazn]

No, it was absolutely great before the speedball.

[Paul Birkeland]

A lot of problems can arise if one black wire on the headphone jack isn't well captured by solder.  Nothing is awry with your voltage checks, so there wouldn't be any reason for your potentiometer to heat up.

[Paul Birkeland]

The black wires on the potentiometer could also use a little extra heat and solder.  Your green wire going to A4/A5 is supposed to be stripped back 1/2" but it looks like it was stripped back at least 1".  If it touches the chassis, you will destroy the power transformer.

[Swollazn]

I can make those changes, I had  a couple Qs. What are symptoms of a blown transformer? And would removing the smaller board potentially solve these issues?

[Paul Birkeland]

A blown transformer will blow the fuse the instant you turn the power switch on and will not produce any correct AC/DC voltages.  To be absolutely sure, one would remove all of the secondary connections on the power transformer and then double check that it still blows the fuse under these conditions.  You 100000% do NOT have a blown power transformer.

You are welcome to remove the small PC board and put the 22.1K resistors back if you like.  In your situation it's not completely clear what exactly the issue is.  What you're describing outside of the smoking potentiometer would be pretty commonly associated with a bad solder joint or improper flux used on the kit.

[Swollazn]

Hm, latest soldering attempt. No huge random crackles so far, only thing I notice is slight movement of potentiometer will lead to the bubbling interference. Also I miswrote what I said before, it wasn't the potentiometer smoking it was the RCA jack.

[Swollazn]

And I think I fixed the buzzing from the potentiometer.. I took the cap off the potentiometer rotary switch and tightened the nut. So far no problems! Again thanks for walking me through. It was a mix of soldering and just tightening the bolts.

[Paul Birkeland]

If the potentiometer doesn't touch the chassis very well, then you could certainly get a little noise.  There just isn't any way I can think of for an RCA jack to start smoking, but often when there's a problem in the circuit, you will start cooking the 270 ohm 5W resistors.