Vintage HiFi Audio Forum

Repair / Help Forum => Repair / Help => Topic started by: scorpio333 on April 01, 2018, 01:52:13 PM

Title: Scarred cap
Post by: scorpio333 on April 01, 2018, 01:52:13 PM
Any idea what causes this? It's a cap on a power supply board. While it looks like it could make contact with the aluminum fin, it's just an illusion. There's no way it could have bent over that far.

(https://uniim1.shutterfly.com/ng/services/mediarender/THISLIFE/021042486451/media/83791914472/medium/1522604742315/enhance)
Title: Re: Scarred cap
Post by: Sir Thrift-a-Lot on April 01, 2018, 06:41:10 PM
I don't know what caused it, but I know I would replace it.   My WAG is a manufacturing defect that didn't reveal itself until power or enough heat caused it to act up.
Title: Re: Scarred cap
Post by: scorpio333 on April 01, 2018, 08:13:16 PM
The JD9 that cap is in has an audible hiss in it. Tried multiple different remedies - tubes, OP amps, rerouting wires, etc and so far nothing has tamed it. So I was in there looking real close and found that cap. Some suggest multiple caps and diodes be replaced in the power supply, I'll add that one to the list.
Title: Re: Scarred cap
Post by: OldiesButGoodies on May 07, 2018, 01:11:54 PM
The JD9 that cap is in has an audible hiss in it. Tried multiple different remedies - tubes, OP amps, rerouting wires, etc and so far nothing has tamed it. So I was in there looking real close and found that cap. Some suggest multiple caps and diodes be replaced in the power supply, I'll add that one to the list.

Scorpio - IMO you are overthinking this. "When I doubt, recap" - that is my motto. But seriously - why not remove the cap and test it?  For more than a basic test I acquired this thing from Amazon on the cheap:

https://www.amazon.com/Multifunction-transistor-Capacitor-Inductance-screwdriver/dp/B071Y5CHPK/ref=sr_1_7?ie=UTF8&qid=1525712694&sr=8-7&keywords=electronics+tester (https://www.amazon.com/Multifunction-transistor-Capacitor-Inductance-screwdriver/dp/B071Y5CHPK/ref=sr_1_7?ie=UTF8&qid=1525712694&sr=8-7&keywords=electronics+tester)

Of course, I would rather have a Sencore cap analyzer like OCCD,  but this does well enough for $16, able to measure ESR etc. Also great if you have a bunch of similar caps built to a certain tolerance and wish to match several to lower tolerance for a left/right circuit recap.

OBG