Recapping a Marshall Club & Country

[louderock]

Was given a nice Marshall Club & Country 4x10 combo. Marshall's answer to the Fender Twin. Appear to be the original caps. Amp dates between 1978 and 1982. They are Daly caps made in UK. They aren't bulging but it seems it would be good to change them and re-tube. Do any of the other caps need to be changed other than the 4 big electrolytic caps? There are 2 other large 32mf 450v caps on the board. Not bulging but do they need to be changed, also? Also a few drops and 4 smaller gold foil caps. Which need to be changed?

 

[SatelliteAmps]

If you are changing them, then change all the electrolytics. The cans, the 2 large 32mf's, and also the bias cap(s).

 

[louderock]

Actually, I think I'll do my JMP 50 watt Marshall first. It's a 1974 year model. What are the differences between this version and a model from 1969? I know that 1974 went to a board instead of handwired, right? When I search schematics, I get one that lists the lead, bass and master volume models on the same schematic but doesn't give year models. So, what makes mine different from a Plexi from 1969?

 

[SatelliteAmps]

They are pretty similar. For a re-cap job, they are essentially the same. The small parts differences aren't anything electrolytic, which is what you would be changing.

 

[louderock]

A few cap questions. I ordered the tubes and caps for my 1974 50 watt Marshall. Ordered from Antique Electronic Supply. The big cans are JJ. The bias caps on the board of my Marshall are 10 microfarad 160 volts. The only cap on their site at this value is Axial Lead. I was going to try the Sprague but it is only rated at 150 volts. Am I okay with the one I ordered or is it worth it to seek out a Sprague? Where would I find the Sprague? Also, the one other electolytic cap at the input stage is 330 microfarad at 10 volts. Not finding this at Antique Electronic. So, where can I get one of these?

This amp isn't as fun to look at inside as my 1974x handwired or my 1969 Hiwatt is. How are you supposed to get to the solder joints since they are under the circuit board? Do you take all of the jacks and controls loose and flip the board up? Looks like a few resistors were changed in the past and they just clipped the leads of the old ones and used them as solder points to the board. Peter Stroud converted this amp from a 6550 to an EL34 amp for me about 10 years ago. Been a great amp.

Also, the bright cap on the volume pot... Labeled Lemco 5k. Is this 5 microfarad? Any recommendations on different values for this?

This has always been a great amp for midrange bark. The tone controls however leave a lot to be desired. They don't do too much but I'm not sure if that's something that can be improved upon or not.

 

[SatelliteAmps]

10 uF @ 150v will work fine. The 330 uF can be found at www.mouser.com. There is a Sprague made one that is 330 uF @ 25v that will work fine. The part number is 75-516D337M025-E3. It costs $0.55.

I think the bright cap is a .005uf, but I could be mistaken. It's on the schematic.

As for soldering on that amp, yeap, you need to go underneath. It's a bit of time to undo it, but not that much. Clipping the leads on the top and trying to solder onto the little bits is ugly, and you can potentially get a lead to drop down and arc when you turn the amp on.

 

[louderock]

Mouser cap on it's way. Thanks.

 

[Swarty]

I think the bright cap is a .005uf, but I could be mistaken. It's on the schematic.

500pF; A .005uF would render the volume control an on/off switch.

 

[SatelliteAmps]

Thanks. That's why I suggested looking at the schematic.

I just looked at one of the schematics for a version of the Club & Country and it is a 1n0 cap (1000pf).

A .005uF (aka a 5000pF) would be a bit off.