Replacing Electrolytics

Jul 23, 2024 Last reply: 1 year ago 6 Replies

HI all,



Electrolytics of all values tend to fall under suspicion when any vintage piece of equipment develops a fault. I'm just seeking a bit of clarification on a couple of points:


1) Axial electros are getting really hard to find new and even my old spares bin doesn't have that many to choose from. I find increasingly there's no option but to replace axials with radials. This results in longer lead lengths than one would like, however. Is that likely to be a problem generally speaking (ignoring the issue of whether they can be accommodated on a board 'expecting' axials).


2) Unused old caps ("NOS" stock). Is there any reason why one shouldn't use NOS electros for repairs? Assuming they can be reformed and pass muster with an ESR meter, of course?



Yes, I know ideally you'd want to use brand new caps, but with so many cheap Chinese fakes around, I'm wondering if I'd be better off using NOS caps from unquestionably high-end manufacturers. Even Mouser's supply chain got infected with these a while ago!


You want to check out

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A reliable supplier of radial and axial lead caps for tube equipment!

John :-#)#

They have some interesting parts and appear to offer a very good service, but I'd still be concerned about them sourcing - albeit without knowing - some dodgy Chinese crap. As I said, if it can happen to Mouser....

NOS electrolytics should be re-formed before re-use.

This is a standard requirement for parts approaching end of shelf-life.

RL

Counterfeit parts exist. Hard to avoid being burned once in a while. Better to deal with a real Brick & Mortar business than buying on Amazon where companies last as long as it takes them to clear out their junk...

Just Radios has provided us with caps for years and I can't think of any failed examples that were correctly installed. I am certain that if something they sold was not up to spec that they would replace it. What more can you ask for?

John :-#)#

Indeed, yes. Unfortunately nowadays I find myself forgetting to discharge them again before fitting! That had disastrous consquences recently with a Uher Stereo Report I was attempting to get back into service. :(

A good axial can have remarkably low ESL, down to 5 nH per inch or so, compared with 20 nH/inch for wire. In boat anchors, you almost certainly don't care as much as in modern SMPS-powered boxes.

Good caps last basically forever at room temperature.

Cheers

Phil Hobbs

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