noise from inside capacitors

[megawhat]

Hello,

been a while since i posted here... hope everyone is well.
I'm having a spot of bother with a little project. It's basically a JCM800 build, but rather than use radial can caps, I opted to use 2x 220uf/350v F&T caps in series for the first two filter stages, and 47uf/450v for the 3rd and 4th.

when the standby is thrown (DPDT before SS rectifier) the 220uf caps appear to hum/tick mechanically, sounds like its coming from inside the cap.

This noise is getting into the audio at roughly the same level as the gain hiss i'd normally expect.

short of re working the ground scheme, I've almost eliminated everything as a problem, but I'm waiting on parts to swap the caps.

Anyone had anything like this happen before?

[John_P_WI]

Do you have balancing resistors across the cap sections?

[megawhat]

If i'm being honest, not originally. I was mistaken in thinking the balancing resistors in were acting as bleed resistors. I have an elevated heater reference circuit which acts as a bleed. so i left the balancing ones out. since then I've realised my error and put 220K/1W across each cap in those first two stages (4 in total).

That hasn't solved the issue, but I'm guessing there is a chance i've damaged the caps?

[Andy Le Blanc]

swap them out temporarily, see if its the issue

I've had that happen, I exceeded the V rating on a ps cap tinkering around

you could hear it pop thru the cap, it was never the same, noisey...

caps are self healing to a degree. it could also be be wire insulation...

give the wire dress a good look for abrasion or solder melt...

[megawhat]

ok.

I'm waiting on two more caps.
I swapped two out (2nd stage) and added some voltage balancing resistors again but the noise is the same.

I also thought the rectifier diodes might be an issue since they took a bit to heat and get the solder flowing and they are cramped together a bit, so i put in some spare 1N4007's with the snubbing caps and careful soldered them in place. This made no difference to the ticking/noise.

so next it's the wait for the 2 caps I need to swap out the 1st filter stage.
might also get some spare switches, I think if the 1st stage getting swapped doesn't solve the issue, the switch is the last think to try.