removing the "death cap" on a 72 JCM800

[PRNDL]

This old 1972 JCM800 Super Lead (2203) has a two-prong cord and polarity switch.

My first step is putting in a 3-prong cord with the ground to the chassis (I put it onto the filament CT cap).

Do you remove the death cap by snipping the positive lead?
It's that simple in Fenders, I just wanted to check because it's a bit more complicated - the board has a bunch of leads.

Thanks

PS
If you're interested, the amp has scratching tone and volume pots. My first suspects are the two .022µ caps to the mid and treble.
-- It turns out to be bad electrolytics. One has an unsightly bulge, and the B+ voltages are all off.

My next question is whether to also replace the two 22µ 1000V caps on the far right of the board across the bridge rectifier. AES doesn't carry them. Someone said they could be removed and not replaced.

[Robert M. Martinelli]

Hi PRNDL,
sorry for asking, but are you sure the amp is a 2203? I'm asking this because you state it's a '72 JCM800, and, AFAIK, the JCM800 series hes been introduced by Marshall only in 1981.....Also, all the 2203 schematics I've seen don't have a polarity switch.....I'm a little confused
Best regards
Bob

[PRNDL]

Bob, you are correct!

It's a 1972 JMP Super Lead, which is almost the same as the JCM800, except for extra input jacks and standby switch.

Schematics are here, and they show the .22µ caps across the power transformer secondaries, and the .05µ death cap on the polarity switch.
http://www.drtube.com/marshall.htm

Here's a photo of 1973 JMP. The 1972 has a standby switch, and all three switches were black plastic instead of chrome. Also, the letters "JMP" are not on the front plate.

[Robert M. Martinelli]

Ok, so it's a 1959....

Some time ago I restored a July '69 one for a friend of mine, the lucky b@$t@rd also owns a fully original '66 strat in candy apple red .....

The .22 uF 1000V caps across the sec should be there for transients, so i think there's nothing wrong in replacing them...

As to the "death cap" you don't need it if you are going to install a three-prong cord, so you can either cut and insulate the wire going from the cap to the polarity switch or disconnect and insulate the wires from the polarity switch to the PT primary winding.....

Hope this helps

Best regards

Bob