LC meter operation
 

I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on
electrolytics, no other type caps. Other caps cause the meter to flash
a high value, regardless of control/voltage settings. The meter will
read value though for all caps. Am I doing something wrong, or is my
meter gimped? Thanks.

A long shot, but ...

Is it possible that your meter actually reads out the equivalent
parallel resistance of the cap (yes, I know what ESR stands for)? For
most caps (but not electrolytics) this would be a very high resistance -
many megohms.

Just a thought. By the way, if you didn't get a manual, you can buy the
instructional video on eBay for $10.

Bill

wrote:

I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on
electrolytics, no other type caps. Other caps cause the meter to flash
a high value, regardless of control/voltage settings. The meter will
read value though for all caps. Am I doing something wrong, or is my
meter gimped? Thanks.

My guess would be that you're measuring small uF caps and the measuring
frequency is such that the series impedance (due to the uF value) is too
high for the system to deal with.

Have you tried it with a electrolytic and non-electrolytic of similar uF?

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Bill Jeffrey writes:

A long shot, but ...

Is it possible that your meter actually reads out the equivalent
parallel resistance of the cap (yes, I know what ESR stands for)?
For most caps (but not electrolytics) this would be a very high
resistance -
many megohms.

Just a thought. By the way, if you didn't get a manual, you can buy
the instructional video on eBay for $10.

Bill

wrote:

I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on
electrolytics, no other type caps. Other caps cause the meter to flash
a high value, regardless of control/voltage settings. The meter will
read value though for all caps. Am I doing something wrong, or is my
meter gimped? Thanks.

wrote in message
ups.com...
I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on
electrolytics, no other type caps. Other caps cause the meter to flash
a high value, regardless of control/voltage settings. The meter will
read value though for all caps. Am I doing something wrong, or is my
meter gimped? Thanks.

Surely it's telling you the caps are good. Try adding a 10 M ohm resistor in
parallel with a small cap and see what it says.
--
N

On Wed, 16 Feb 2005 19:07:02 GMT, "NSM" wrote:


wrote in message
oups.com...
I recently bought a Sencore LC102 off of e-bay. It was calibrated just
prior to sale. When checking caps for ESR, I only get readings on
electrolytics, no other type caps. Other caps cause the meter to flash
a high value, regardless of control/voltage settings. The meter will
read value though for all caps. Am I doing something wrong, or is my
meter gimped? Thanks.

Surely it's telling you the caps are good. Try adding a 10 M ohm resistor in
parallel with a small cap and see what it says.

That will not tell him anything useful. ESR is important only when it
gets over an ohm or two (depending upon cap value and voltage rating).

If you are measuring small value capacitors (1 ufd or less) the ESR
meter will not be accurate as the the ESR of the cap will be swamped
out by its capacitive impedance.

Remember that the ESR meter uses a high frequency test signal so that
the capacitive impedance is insignificant with respect to the
equivalent series resistance of the capacitor. When the capacitive
impedance gets large (small cap value) the meter cannot tell the
difference between that and the ESR.

John

Thanks alot to all that replied. I haven't compared electros to other
types of same value, but will try this. I don't remember the values of
other's Iv'e checked, since I only used this meter once, but I'm pretty
sure they were of small value. I will reply with results when time
permits....working 20 straight days starting yesterday. Thanks again to
all.