71' Marshall super lead, Replace capacitors?

[FriedWires]

Hey to all you marshall masters, I've done a cap job on a 71' super lead 1959. Does anybody know if the 2 Hunts .22 @ 1000 DC caps are electrolytic and if so what do you replace them with? Did a complete tube + cap job, set bias, etc... I am getting a type of oscillation.(tremelo like) Thought of shortening grid wires or maybe sheilding the wire. Used F&T's, sprague's + JJ's. Charged it up slowly with a variac. Just curious if those Hunt's caps could be the culprit. Any info is greatly appreciated- thanks, FriedWires

[didi]

It depends where they are in the circuit. Any indication of their function might help?

[Gtr_tech]

Hey to all you marshall masters, I've done a cap job on a 71' super lead 1959. Does anybody know if the 2 Hunts .22 @ 1000 DC caps are electrolytic and if so what do you replace them with? Did a complete tube + cap job, set bias, etc... I am getting a type of oscillation.(tremelo like) Thought of shortening grid wires or maybe sheilding the wire. Used F&T's, sprague's + JJ's. Charged it up slowly with a variac. Just curious if those Hunt's caps could be the culprit. Any info is greatly appreciated- thanks, FriedWires

They're not filter caps....leave 'em.

[tboy]

Does anybody know if the 2 Hunts .22 @ 1000 DC caps are electrolytic and if so what do you replace them with?

A value of .22 isn't likely to be electrolytic.

[jrfrond]

Those caps are "snubber" caps to keep the Standby switch from arcing when activated and burning the contacts. They have nothing to do with the signal path or power supply and can be left alone.

[acorkos]

if you do decide to replace them, Mouser Electronics - Electronic Component Distributor carries these...they're small and fit the space available well:



Mouser Part #: 5984-940C10P22K-F
Manufacturer Part #: 940C10P22K-F
Manufacturer: Cornell Dubilier
Description: HV Metallized Polypropylene Film Capacitors 1000V .22uF

[FriedWires]

Hey , thanks everyone! All this info is much appreciated!!!!!

[bsmith]

Hey to all you marshall masters, I've done a cap job on a 71' super lead 1959. Does anybody know if the 2 Hunts .22 @ 1000 DC caps are electrolytic and if so what do you replace them with? Did a complete tube + cap job, set bias, etc... I am getting a type of oscillation.(tremelo like) Thought of shortening grid wires or maybe sheilding the wire. Used F&T's, sprague's + JJ's. Charged it up slowly with a variac. Just curious if those Hunt's caps could be the culprit. Any info is greatly appreciated- thanks, FriedWires

If you installed new F&T's you should never charge up slowly. Those caps have already been pre-formed by the factory. \

[pdf64]

It's not necessary, but I don't see how it could hurt anything.

[melvin]

So the oscillation is not hum? You say it's like a tremelo, so really low frequency? Does it sound like motorboat? Is it on all the time or just when you turn it up? You seem to think it's a parasitic, and shortening grid wires will help, of course. And that particular amp may need it, regardless.
Did you recap the bias supply?
Also, sometimes with that age of an amp there are many bad solder joints to be found. And the resistors in the power supply often need changing.
When I do a cap job, I also replace all the plate load resistors, all the resistors in the bias supply, clean/retension all the sockets and pots, check the grounds. I'm always surprised how many problems this can solve.

[FriedWires]

I ended up sheilding the input grid wires with the sheilding ground at the front of chassis. No more ugly out of tune sound. Yes I did replace the bias caps and also had to replace 2 noisey plate resistors and one of the bias resistors was way out. I've tinkered with enough amps where I thought I had some experience, but this amp was trouble shooting 101. This amp wasn't kept in a good dry environment for apart of its life that I can tell. Now that I've given it a tune up and then some, it sounds like an old marshall again. I usually do what you recommended to every amp. Thanks for the input!