On Jan 24, 6:52*pm, "Phil Allison" wrote:


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

Also, your math is wrong hotshot.

G²