Marshall Power Break Problem

HHwarner

Following on from my other thread JCM 800 biasing problem, I mentioned a problem with my Marshall Powerbreak, anyway I finally got round to taking the cover off for a poke around and found this. I have soldered it back on but the insulation was split. I wound insulation tape around it, It all works again now so touch wood all is good.

ICBM

HHwarner said:

Following on from my other thread JCM 800 biasing problem, I mentioned a problem with my Marshall Powerbreak, anyway I finally got round to taking the cover off for a poke around and found this. I have soldered it back on but the insulation was split. I wound insulation tape around it, It all works again now so touch wood all is good.

Ouch. Good thing you found that!

I'd be inclined to use some hot-melt glue to really secure it in place.

HHwarner

Yes ill stick it down good and proper, will it hurt that the insulation has split. I have wound insulation tape around it but didn't know if the wire at the lower terminal (it goes from the top down) was also under the insulation. Iv taped under that wire so it is still exposed. Im guessing this is some sort of choke?

ICBM

Unlikely to be a problem. Yes, it's it's a choke (inductor) and is wound with wire that's already coated, so the plastic sleeve is more to hold it together than to insulate it. It should have only two connections, one at each end, so both should be connected through the board and soldered. If you can bend or 'rivet' the wire ends over before you solder them it will make it even more robust.

If the insulation has split as well as it coming unsoldered, I'd suspect the unit has been driven very hard by something with an excessive high-frequency content which has overheated the inductor… maybe a distorted solid-state amp. (Unless you know the history of it!) It probably won't have done any serious damage though, it's extremely hard to burn out since really it's just thick coper wire.

HHwarner

I'm not sure of distant history as I bought it second hand. The guy I bought it from used it in a 4 input non mv JCM 800. Would some epoxy glue ie araldite be ok to stick it down. Iv no hot glue. Cheers for the help. Scott

ICBM

HHwarner said:

I'm not sure of distant history as I bought it second hand. The guy I bought it from used it in a 4 input non mv JCM 800. Would some epoxy glue ie araldite be ok to stick it down. Iv no hot glue. Cheers for the help. Scott

Yes, anything that stops it vibrating. You don't need much. It's a good idea to do any other component which looks like it could move, too.

Those non-MV 800s are really trebly! That might well explain it. They're probably the loudest 50 and 100W amps Marshall ever made and are not subtle, in any way.