"Bob Parker" wrote in message
...
That's an excellent explanation, mate! You wouldn't believe how
many times I've been asked "What's a good and bad ESR reading?" as
though it's a hard and fast value for a capacitor like its working
voltage is.
I'm going to make it into a text file and send it to people when
they ask me that question. Thanks!!

Regards
'Terry'

Hi Bob

Ha ! Fame at last ... Please feel free. What's with " Terry " ?

Arfa



On Sun, 09 Apr 2006 11:13:56 GMT, "Arfa Daily"
wrote:

Although I've said on many occasions that the Dick Smith meter gives
unambiguous readings, that statement has to be tempered with a degree of
experience. Interpreting ESR readings is a mixture of art and science, and
if you deal with the subject a lot, you will rapidly get a " feel " for
bad
caps. As others have said, a lot depends on capacitor type, and where it
is
located in the circuit, as to whether its going to cause trouble. Surface
mount electros tend to have a higher ' natural ' reading than their
corresponding-value conventional types, so it's often a good plan to do a
comparison with a known-good similar type.

I use a Dick Smith virtually every day, and the chart on the front is, in
general, a very good guide, but it should be used as just that, not a
definitive good / not good indicator for all cap types. In normal
circumstances, I would consider anything giving a reading of twice or more
the *expected* value, to be at least on its way, if not truly u/s. Other
indicators help with the suspicion of a bad cap. These are -

Its proximity to anything that gets hot

The ripple ( or other 'AC' ) circumstances under which it normally works,
and how hot this causes it to normally run

To some extent, the normal voltage that's across it, compared to its rated
voltage

Arfa