"Overflow" reading on a capacitance tester - what does it mean?

Thread Starter

jbar

Joined Oct 25, 2016
5
I have a MESR-100 ESR meter and have the same issue. It is designed to test capacitors on the board/incircuit and works for many of those I've tested. However, I have board with two 0.47uF, 50v electrolytic capacitors and get an overflow message when testing. They have been discharged. Since this meter goes to zero on a direct short (clipping the leads together), can I properly assume there is no resistance in the capacitor for some reason?
 

crutschow

Joined Mar 14, 2008
26,997
Since this meter goes to zero on a direct short (clipping the leads together), can I properly assume there is no resistance in the capacitor for some reason?
I don't follow. o_O
You are reading an OF message, not zero.
OF indicates the capacitor is larger than the highest range, or you have too much resistance in parallel with the capacitor.
 

Thread Starter

jbar

Joined Oct 25, 2016
5
Do not hijack someone else's thread.
You now have your own thread.

Moved from here:

https://forum.allaboutcircuits.com/...a-capacitance-tester-what-does-it-mean.97208/
Apologize if I highjacked the thread. The first post in the thread was someone with the same problem I am having it’s just using another brand of test equipment. Usually it’s expected users search the forum before asking questions. I did this and asked a question to further clarify the issue. Sorry.
 

Thread Starter

jbar

Joined Oct 25, 2016
5
I don't follow. o_O
You are reading an OF message, not zero.
OF indicates the capacitor is larger than the highest range, or you have too much resistance in parallel with the capacitor.
It could be the meter is faulty, as it reads OF when the test leads are not connected to anything, so my presumption is the cap either has zero conductivity or it’s a bad tester. I don’t know enough about the tester to say whether a OF message when the leads are not connected to anything is normal or not. I’m ordering a new tester. Either way I will not post on this thread again as I’ve been told I’m hacking this thread. Thanks for trying to help.
 

MrChips

Joined Oct 2, 2009
23,233
This is now your thread. You are allowed to post here as you wish.

Please clarify what your meter is showing.

A low capacitance value being displayed is a different symptom from an OF reading.
As the previous member has stated, OF indicates overflow, which means that the capacitance being measured is greater than the range selected on the meter.

Are the capacitors that you are testing removed from the circuit board?
 

Thread Starter

jbar

Joined Oct 25, 2016
5
This is now your thread. You are allowed to post here as you wish.

Please clarify what your meter is showing.

A low capacitance value being displayed is a different symptom from an OF reading.
As the previous member has stated, OF indicates overflow, which means that the capacitance being measured is greater than the range selected on the meter.

Are the capacitors that you are testing removed from the circuit board?
This is a 47uF capacitor. The meter is designed to handle up to 10F caps.

The meter is a MESR-100. A little background on the meter: It's a new meter, that's why the reading I get is being questioned. Per instructions when I turn meter on, I connect leads and press Zero button to zero out the meter. After zeroing the meter if the leads are open (not connected to anything) the meter reads OL which stands for overflow or overload. When you connect a known good capacitor it will show a proper ESR value, so I 'think' the meter is working properly. However when I connect to these 47uF, electrolytic capacitors it continues to read OL instead of giving me an ESR value. It is designed to work with capacitors on-board. There are two of these 47uF caps on the board and I removed one and made absolutely certain it was fully discharged and tested it off-board, with the same result: OL.

As additional information, I do have a cheap chinese component tester I use for checking resistors, caps, etc when doing projects (I'm a HAM). On this tester the cap is reading 12uF with an ESR of 0.14Kohms.
 

atferrari

Joined Jan 6, 2004
4,278
You are instructed to zero the meter with clips already connected to the cap under test?

That I can recall, to measure caps I short terminals, zero the meter and then connect what I need to measure to them.
 

Thread Starter

jbar

Joined Oct 25, 2016
5
You are instructed to zero the meter with clips already connected to the cap under test?

That I can recall, to measure caps I short terminals, zero the meter and then connect what I need to measure to them.
Correct, I connect leads together, zero the meter, then connect leads to cap and test cap.
 
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