NOS Mallory Cap Can?

[ALBATROS1234]

I know this may be controversial, but I just purchased a tube lot for a very reasonable price which had some tubes I needed but there were also some NOS boxed relays, pots, resistors and a cap can. It is a NOS/NIB Mallory Cap Can (40-40-40 @ 450v) Obviously a usable can in our neck of the woods. I could theoretically reform this and put it in an amp. But there is part of me that wonders if this will be bad form and I just wondered what you guys would think about using a NOS NIB Electrolytic Cap Can. I dabble into radios, R2R's, record players etc as well as vintage guitar amps and I have found in existing circuits usually coupling caps and such are generally leaky to some degree even if the circuit functions pretty well as intended but I have had 50/50 success on reforming cap cans like this which were used and in circuit and some cases are still presently working well after reforming 5-6-7 years ago plus. I know some would say throw all capacitors which are not new production in the trash, but I sometimes feel if it isn't broken don't fix it.

[ALBATROS1234]

Ripley's Believe it or Not: Check out the link below, this is the part number on this cap can box. Maybe I should try to resell this can LOL because the whole lot of tubes I bought was $20 plus shipping and I got all NOS, 3, 6SF5 octal preamp tubes, a 5U4, an 80 rectifier (a 4 pin 5Y3) plus some horizontal deflection amps which are basically a 6L6g with a top plate connection and various other tubes including some Novar triple triodes and various compactrons.

https://www.vivatubes.com/nos-nib-vintage-mallory-type-fp377-1a-can-capacitor-40-40-40mfd-450-450-450vdc/

[WimWalther]

Definitely try reforming the cap. If it's successful, test it for capacity and also ESR, if possible. There is no reason not to use it, if it can be brought around.

[ALBATROS1234]

Yea, that's what I am thinking. It is literally new in the box so I would imagine is the perfect candidate to reform. It seems like most cases the multi cap cans respond well to reforming. On my 1954 Kodak projector amp a slight hum came back and eventually one cap failed where it started a slight hum and made a tremolo type sound. I basically just added a cap with a terminal strip, and it has been working since which is about 5 years at this point. Also, I have a nice 1962 Magnavox Radio/Record Player console which worked fine for after reform for a few weeks them it started giving minor hum problems after the amp warms up and plays for a half hour. If you turn it off it goes back to working right until it is played for a while again so that one, I will change. I have also had some that didn't respond at all to reform. But I have a more than a few 1930's and 40's Philco's, Zeniths, and many more radio and record players and tape recorders which continue to operate perfectly I just never have taken an old part and built it into a new amp build.

[WimWalther]

In any conventional electronic power supply, it's usually the 1st cap, the one right off of the rectifier, that takes the most abuse. Consequently, this is often the first (sometimes, only) cap to fail outright. If you replace only that cap (or cap section) you might find that the rest of the supply continues to work just fine.

It's usually not the right thing to do for customer equipment, but when it's your own stuff, it's more acceptable.

Fisher did their PSUs right on most of their 60s-era gear. They used a SS voltage doubler for the first stage, with a pair of discrete axial lytics. These are often bad, but very easy to replace.. and the rest of the supply then comes around fine.

[ALBATROS1234]

Yeah, that's basically what I have found too. I just got finished tube rolling these 58' RCA 12AX7's Lowery pulls and boy wow these sound fan-freaking-tastic. I am not a rich man so I would say more than half of my guitar amp tubes comes from pulls as I am always buying a R2R, record player or something for $20 and getting a few nice tubes. I have a couple long black plate RCA's from pulls and they test good but not great or NOS. I think they really sound good, I have a few more short plate RCA's they are OK. I have gotten Mullards from pulls that test well and I even got an Amperex Bugle Boy from a lot which the guy claimed to have gotten all of the "good" tubes. When I was examining, I noticed the alpha numeric codes from a Holland 9 pinner with obvious long triode plates and I could just make out the bell of the trumpet, that one sounds damn good. I mostly have Sylvania pulls which I like quite a bit, various other brands from the 50's to 1970ish. I have bought some power tubes and preamp tubes but usually from someone who is saying "Test Strong" or "Test good" when they are selling for sub $40 on a 12AX7. Again, I don't have Brent Jesse money. When I pulled these from that organ and saw beside the Lowery logo 58-52 274 EIA code I was hopeful, when 5 out of 6 tested NOS with 2 on the high end of NOS I got excited. Today I finally cranked my 54' Kodak projector amp which I modded and normally use a late 50's long plate Mullard pull in V1 which sounds great, These RCA's smoke that Mullard and sound unbelievable. Don't get me wrong, as I am sure you know different manufacturers tubes have different tonal characteristics. Mullards, Amperex, Telefunken, Eico, Sylvania, Hytron, Raytheon all have a slight different tone/feel. One of these RCA's now lives in that amp permanently.