Snap, crackle, POP! Chopstick test?

[dbx]

Finished retubing my Vibrolux and am enjoying some really good tone out of it...BUT

now I hear an intermittent crackling/popping at higher volumes with more bass content. I can also replicate it by tapping my hand on the top of my amp. I had this when I first got the amp, it had a bunch of cold/broken solder joints. I think I broke something some months back. During setup, the amp tipped over on it's back (I was using an ampwedge and went too far, evil thing :FM.) It wasn't powered up at the time and seemed to be OK but did make some initial light crackling noises before it "straightened out".

Apart from poking around with a scope (don't have one) and DMM, is it possible to visually check and probe connections with a chopstick (I read a thread where someone suggested this approach) while powered on? Any possibility of shorting something out while doing this? The last resort is to take it in or reheat the majority of solder joints I can see and hope I "get it"...

aaaggghhh, so close but yet so far...the sound is really juicy but interrupted by this...thanks. :o

[WaltC]

checking the tightness of input and speaker output jacks, tube sockets, cleaning and retensioning the tube sockets and cleaning the tube pins (always a good idea even if it isn't the current problem <G>, careful, the tube sockets are connected to some high voltages if the amp is on or the caps haven't been discharged) could uncover the probelm.

if not, then doing a thorough chopstick test on all the solder connections, including the ones on the pots and on the tubes, should lead you to the problem. Don't forget to check the solder joints in the filter cap can on under the "dog house" too. Pay particular attention to the resistors too because they (especially the plate load resistors and screen resistors) can crack and provide intermittant or no conductivity.

See what turns up (and be CAREFUL of course)...

[dbx]

Hey Walt, thanks for the reply...

I can do all of the physical adjustments with the amp off, but should I drain the caps even if I'm not working on the sockets? Ha I just noticed the #1 jack nut on the Vibrato side was loose...just tightened it, gonna fire it up and see if that's all it was...thanks again for the input...

:AOK

[dbx]

WALT GETS THE GOLD STAR!!!!

That was it..a loose jack nut....you saved me some $$$ man, thanks!!! Tightened down the nut, cranked 'er up to 10 on all dials and it's solid on both channels...not even when I bang on the top of the amp...

(Nice amps by the way, looks like you do some good work!)

Lunch is on me...feel like Chinese? ;)

[Blue Strat]

Before you do anything more dangerous or complicated, clean all tube pins and sockets. Details in the FAQ on my website under Resources.

Retensioning sockets would be next on the list. If tapping on the board brings on the pops, it's probably another cold solder connection. See if you can narrow down a particular section of the board and resolder everything in that area.

[dbx]

Thanks Mike, looking forward to trying those tubes you're sending...
:BEER

[WaltC]

chinese sounds good to me! Hot and Sour soup and honey-dipped walnut prawns for me....<G>

[Witek]

kellogs rice crispies!