Marshall amp Cap Anamoly, WEIRD!

[charvel750]

Guys, I have two Marshall 3203 heads. One has TWO caps installed (they came stock with only 1) and the installation is very unusual. Most Marshalls the blue caps stick up like a tube, but this one has the blue cap wired INSIDE the amp near the circuit board, and wired right to the stock cap. Was this done aftermarket? I don't get it. What's going on here?




Here's the other Marshall 3203 without that strange cap placement:

[Spivonious]

So the bottom one doesn't have the second cap, right? That makes me think that the top one was modded.

I'm far from an electronics expert though, so let's wait until someone more knowledgeable gets here.

[Cygnus X1]

I think it was modded.
Extra filtering to reduce hum.
Is one quieter at idle than the other?

[jgcable]

Its eather one of 2 things.
Its either an extra cap for extra noise filtering..
OR
The original cap blew and the person repairing it couldn't find a 100uf cap so they wired 2 50uf caps.

[jgcable]

If one of those 3203's was mine at one time I am pretty sure that it was modded by its previous owner.

[Cygnus X1]

Meh, that's two 50's going to two different places.
More than likely B+(A) and B+(B).

A single 100uf wouldn't duplicate that...it has to be two seperate 50uf caps to do it.
The two 50's are in that one canister.

[jgcable]

Meh, that's two 50's going to two different places.
More than likely B+(A) and B+(B).

A single 100uf wouldn't duplicate that...it has to be two seperate 50uf caps to do it.
The two 50's are in that one canister.

Thanks for the tech info.

[Cygnus X1]

...Unless the two 50uf's are tied so they are providing 100 uf to one of the B+ rails.
I can't really see how it is wired in.

A clearer pic of the bottom of the extra cap would help.

[DonP]

...Unless the two 50uf's are tied so they are providing 100 uf to one of the B+ rails.
I can't really see how it is wired in.

A clearer pic of the bottom of the extra cap would help.

That's what it is - a dual 50 cap wired as 100.

Everyone mentioned the lower noise, but an additional "benefit" supposed to be a tighter / better bass response.

For example, in the 80s Marshall changed the 100 watt models by reducing the number of blue cans by 1. People started noticing a difference and started searching for the 100 watt models with the extra can.