Testing electolytic caps in situ

[Bignumbas]

Came across this gem of a method this week.
I always have problems with cap testing and without an ESR meter its even harder to know if the cap is good even if it tests to the proper value when it is removed from the board.
This method works with the caps still installed, no desoldering.
To me it appears to work on the same principle as an esr meter but instead of seeing an ohm reading you get a volume variation that you hear.





I made up a test unit out of junk I had lying around. Samsung tv speaker, small amp out of old pc sound speaker sytem.
Plus I use a free music app on a phone to supply sound.
Works great! 

[tjohnson]

Totally funky music

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