With any ESR meter there are 'gotchas' to beware of. Any
ceramic caps in parallel with a 'lytic will mask the true condition of
the 'lytic.

** Totally insane ******** !!!!!

A 0.1uF ceramic has an impedance of 16 ohms at 100KHz - while a typical
100uF electro has an impedance of 0.16 ohms at 100kHz. That is 100 times
less !!!

Imbecile.


If it reads bad, it IS but if it reads good it might not be.


** Only time that is ever true is if the electro is shorted - internally or
externally.


May times I've run into boards with many caps of the same value.
If one of those is bad I change all of that value figuring if one is
bad the others aren't far behind.

** Not a bad idea - if all the electros have been subjected to the same
temps for the same times.

Also, the output caps in SMPS need to be nearly perfect.


** Well, that may be so in some cases.

But designers usually leave a margin for component variations and some
deterioration in electros.

Once the ESR of an electro rises by more than 50%, it may be time for
replacement - cos it is now gonna keep rising.



...... Phil