in circuit ESR meters: GM328 Mega328; resistance from leads?

[SpiderWaffle]

I was wondering if anyone knows if these work okay for testing in circuit ESR for bad caps. I was a bit worried their internal resistance, the leads, might be too high to get precise enough readings. I'm not trying to be a technician and fix things all the time, but every now and then finding bad caps would be nice.

https://www.amazon.com/gp/product/B01H6QKVOU/

https://www.amazon.com/Yosoo-Display...dp/B00OOQC2E8/

https://www.amazon.com/MK-328-TR-LCR...dp/B01N3OEBJP/

[stj]

Re: in circuit ESR meters: GM328 Mega328; resistance from leads?

the leads can be zero'd out in calibration mode,
but in circuit testing is bogus because of parallel circuitry.
and not just with those testers, but with any.
at the least, you need to lift one leg off the board to isolate the cap your testing.

[SpiderWaffle]

Re: in circuit ESR meters: GM328 Mega328; resistance from leads?

Can be zeroed out but with such low voltage if the internal resistance is too high I don't think you can get accurate readings. I suppose precision doesn't matter.

If they're not in parallel aren't you good to test ESR?

And for even for parallel, You cannot measure the individual ESR of similar value capacitors in parallel, but if the combined ESR is low enough then it would be reasonable to at least get a better idea of which caps to check first. The fail criteria for a capacitor is going to be at least a 50% increase in ESR.

So you're not getting precise readings, but if there's any accuracy you should be get some idea of the ones 50% or more off.

[stj]

Re: in circuit ESR meters: GM328 Mega328; resistance from leads?

they are IN CIRCUIT, they will be in parallel with semiconductors & stuff.