Choosing an in circuit ESR tester

[rb0746]

I am beginning to realize the the value of such a tool for trouble shooting .
I was hoping to get some help in my selection/purchase.
A Couple things to keep in mind are: 1) I live in Canada and 2) I am on a budget .

[bp1]

Re: Choosing an in circuit ESR tester

I have just bought the esrmicro V4. Here are some links which you may find interesting on esr meters. They certainly helped me in my purchase choice.

https://www.badcaps.net/forum/showth...257#post114257
https://www.badcaps.net/forum/showthread.php?t=7394

Hope the above helps

kind Regards
bp1

[tmwalsh]

Re: Choosing an in circuit ESR tester

I thought that all of the ESR meters worked with the capacitor under measurement out of circuit. Am I mistaken?
tom

[Radio Fox]

Re: Choosing an in circuit ESR tester

I thought that all of the ESR meters worked with the capacitor under measurement out of circuit. Am I mistaken?
tom

The only certain way of knowing if the ESR is OK, is to measure the capacitor out of circuit.

Depending on the circuit layout, it is sometimes possible to measure the ESR while the capacitor is still in-circuit. If you measure a high ESR of a capacitor while in-circuit, then it is bad, but if it measures OK while in-circuit, it could be good or bad.

Many circuits, especially PSU's have electrolytic capacitors in parallel. If your ESR meter shows both of these capacitors to be OK, it could be that one of them is still bad, but the good one in parallel is masking the high ESR.

[PlainBill]

Re: Choosing an in circuit ESR tester

I would add to Radio Fox's explanation that interpreting the readings in terms of the circuit can help eliminate some of the guesswork. For example, if four capacitors are in parallel, the ESR spec of each capacitor is .06 ohms, and you get a reading of .03 ohms, the capacitors are bad (the expected reading would be .015).

HOWEVER, capacitors are usually specified quite conservatively. When new, the capacitors probably each read .01 or .02; the circuit would work reasonably well if the total ESR was .5. Early this year I picked up a fairly new Philips LCD TV that was exhibiting the classic 'bad caps' symptoms. Most of the time it would start after a couple of tries.

Opening it up, I found a number of bloated caps. Checking their ESR in circuit showed they read well over 1 ohm. Removing them from the circuit, each read much higher. The new capacitors were spec'd at something like .06 ohms, all read .01 or .02. Other similar capacitors in the TV gave readings well below .05. And when the caps were replaced, the TV worked perfectly.

PlainBill