On 2019/05/14 8:23 a.m., John-Del wrote:
On Tuesday, May 14, 2019 at 9:55:17 AM UTC-4, Bob Engelhardt wrote:
Are these "bulging"? How much bulge is too much? Or is _any_ bulging
to much? "If you can see that it's not flat, it's too much"?

https://imgur.com/GymXlUb

Thanks,
Bob

Bulging is not an indication of the condition of a capacitor. I've seen many physically large capacitors in power supplies show some bulge and be dead on for value and ESR, and others that looked brand new and were decidedly low in value and high in ESR.

Either pull them and test them or at least scope across them (watch for hot ground with your scope).


In this case (I checked the photo) the bulging is certainly indicative
of a dying capacitor. Another clue is the black plastic sleeve has
pulled away from the top of the cap. As a matter of course we replace
any caps where the sleeve has shrunk - that is an indication of the cap
overheating or simply being in too hot an environment. A new cap has the
sleeve covering around 25% of the top of the cap, if you can see signs
of shrinkage then time to test and likely replace the cap.

As an aside, it is interesting that early amplifiers put all the
transistors in sockets (pretty reliable devices actually) and yet
soldered in the most failure prone part of all - the caps! Only on the
odd rare tube equipment did you see electrolytic cans that had an octal
style plug. Of course if the caps were in sockets then you would have
one more junction to fail (OK two junctions per cap) but at least you
could replace them more easily.

Ducking.

John ;-#(#

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