'69 Bandmaster Reverb - really odd issue

[gui_tarzan]

I just got done re-capping this (filters, bias, trem tube cathode cap) and it seems to be working really well. But there is a static issue I have never seen before on these and it's really perplexing. Every so often I hear the static that goes with the trem oscillations. Sort of like sh-sh-sh-sh. Not constantly, just a couple of seconds and it quiets down for several seconds and does it again.

If I very lightly run my hand across the chassis top front edge over the trem channel volume and inputs (as shown in the pic) I get lots of static and hum. If I press my hand down on the edge and slide it I don't get it, but if I lightly drag my hand across that section of the chassis I do. Just that area, not on either side of it.

WTF???

[Reeltarded]

Reflow all the grounds, I think.

[martin manning]

Yes I think a ground issue for the touchy chassis. Grounds made through the pot and jack bushings in that area would be prime suspects.

[Stevem]

The intermitant hiss due to a poor grid connection on a preamp tube, so it's time to retention that issue socket and or replace it and also check the tube pins for a tarnish condition.
The poor connection make for a very high resistance!
Note that it's not the trem tube socket, it's more likely the gain stage before or after the trem stage.
I just had this same issue 3 months ago, but not on a Fender.

[gui_tarzan]

I'll start there Steve, I typically re-tension all tube sockets as part of any work I do anyway. Re-flowing ground connections isn't a bad idea either.

[Richie]

Also wouldn't hurt to remove the knobs and tighten the pot nuts. And jack nuts. Sometimes they get loose over time.

[Reeltarded]

^^ Yeah that

[gui_tarzan]

Ok, so I reflowed some of the solder joints on the chassis, as well as on the board where it looked like someone changed a ground wire or two in the past. The sockets were all re-tensioned (prior to the first post), and the chassis static was gone so it must have been an iffy ground. The next item was to check the reverb since the owner said it wasn't working. That ended up being a bad cable from the pan to the back of the amp. Easy fix. It's all back together, everything works and it sounds great!

[Stevem]

Cool deal, so it was a high resistance made for by that bad ground! easy enough fix!!