I bought an NOS .68uf Mustard for my 1972 Marshall V2A slot, should I........

H

harddriver

Well-known member
pull all the preamp and power tubes and bring the amp up slowly over 6-8 hours on a variac up to about 50-75% of 120 ACV's to let the electrolyte reform in the new nos mustard cap or just pour the coals to it? :unsure:

The NOS .68uf cap tests perfect in capacitance but obviously they have been sitting for years with no power applied to them.

For aesthetic reasons I bought this NOS mustard cap so I am replacing a Synergy .68uf on V2A which works and sound great I just wanted an actual NOS mustard there.

I've done the variac procedure in the past with amp builds that used NOS mustards and it always works well but this being just one capacitor I thought I would ask others opinions if it was worth the trouble to do it for just one cap.
 
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fusedbrain said:
There is nothing to reform, its a film cap.
Let er rip
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This is what I thought too. Only electro-lytics need to be 'reformed' afaik.

I just put two 22n Mustards in the tone stack spots in my '69 clone for same reason, it was the only non-Mustards in the amp and I wanted it all Mustards just because. The Synergys sounded fine. But I just fired it right up...they were still warm from soldering. :cheers:
 
I don't know why but I was always under the impression there was some type of electrolyte between the layers of the film/foil but you guys are 100% correct. :2thumbsup:

Thanks for all the info and clearing that up! One less thing to do after my retrofit and rework is done, I'm adding a missing Iskra that I could not salvage when I pulled the old 330uf Erie on V1A and a new power cord as well.

Merry Christmas everyone!
 
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harddriver said:
I don't know why but I was always under the impression there was some type of electrolyte between the layers of the film/foil but you guys are 100% correct. :2thumbsup:

Thanks for all the info and clearing that up! One less thing to do after my retrofit and rework is done, I'm adding a missing Iskra that I could not salvage when I pulled the old 330uf Erie on V1A and a new power cord as well.

Merry Christmas everyone!
Click to expand...

In this type of capacitor, it's a dielectric, not an electrolytic. Think of a dielectric as a non-conducting insulation between the capacitor plates. It prevents direct electrical conduction. No forming/re-forming necessary like in an electrolytic filter cap.
 
FourT6and2 said:
In this type of capacitor, it's a dielectric, not an electrolytic. Think of a dielectric as a non-conducting insulation between the capacitor plates. It prevents direct electrical conduction. No forming/re-forming necessary like in an electrolytic filter cap.
Click to expand...
Sort of like aluminum foil layers separated by a plastic film layer. Rolled up into a tube with leads on each layer of aluminum foil. Then gooped.
 
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