Maintenance for My Marshall Amp(s): w/pics for fanatics

[knobtwirler]

In the last couple years these 2 70s amps started doing a crackling/ocean type sound if you stopped playing for a minute or so, and it would clear up after you started playing for the most part unless you were playing delicately and quietly. I ran this by a friend who deals with these amps and others all the time, and his sensible advice was to just spray out all the tube sockets, tighten the ground, it's probably nothing, and in fact these things tend to be mostly nothing and people jump to the most complicated conclusions about their amps' parts. So, for those of you that can appreciate these pics, here's one of the amps during the removal from its case and after a cleaning. But, what does one do to tighten down the ground? I stared at the wiring a bit, and I don't know electronics, so I couldn't easily see what I could do. This is a two-prong AC cable and this amp tends to pass voltage onto my guitar strings and anything else metal that's grounded to my apartment's electrical outlets. Any help is much appreciated.

[RefD]

i'm not seeing any photos, just blank pages.

[knobtwirler]

i'm not seeing any photos, just blank pages.

I don't get that. The link works for me. Anybody seeing pics? BTW, Matt Wells modded this amp for a Master Volume so I can actually play it, although he wished I didn't.

[jaguarsg]

i'm not seeing any photos, just blank pages.

ditto.

[Huntlabs]

i'm not seeing any photos, just blank pages.

Me too. No photos even when I try to open in another window.

I know Fender tube amps. There are similar to Marshalls. The standard answer for Fender amps would be:
1) check the tubes, especially the preamp tubes. Oh, and retention the tube sockets.
2) Clean / spray all the pots
3) Replace the Filter Capacitors, the big ones that filter out the AC / hum. They can go bad and bad bad things can happen.
4) Noisy resistor? Don't know in Marshalls what common ones are the problem.

Any amp over 25 years old could do with new filter caps. They don't last forever and ac in the circuit doesn't sound good at all.

You might go to the Fender Discussion Page / Amp projects and repairs for some better advice. There are some good amp techs that hang there.
J

[knobtwirler]

My usual file storage site no longer exists, so I used a new one today, turns it blows cause you can't see my pics. Anybody recommend a free one that works, I'll upload them so they work. Thanks for the advice. I was convinced they need new filter caps, like you said, and that's when my buddy said that stuff about overdoing it, maybe he didn't quite understand how old my amps are in the short conversation.

[RefD]

i keep having to remind myself that 1988 was 20 years ago.

[knobtwirler]

Yeah, this first one is 35 years old. I'll take pics as soon as I get to the second one, a 1977 50W JMP.

[RefD]

seeing them now.

looks sweet.