Atlas ESR60 - Low ESR Meter

[BigAlNZ]

Heya guys,

Well I splashed out and got myself a Low ESR meter. I went with the Atlas ESR 60.

So I decided to test it out on a bunch of new caps I got here which are mainly Panacsonics like 1000uf 6.3v with some 1500uf 10v, and 1000uf 10v, 1200uf 6.3v.

Most came in at about 0.05 Ohms through to 0.12 Ohms. So I am guessing this is normal range.

Now I grabbed the only bad motherboard I had lying around and put the meter on a clearly venting cap (not the worst example I have seen but it does have a little electrolyte out the top). The cap is rated at 6.3v 1500uf 105deg. It looks like its marked RLS / Ost?

Anyway to my surprise it measured 6000uf (waaaay out) but only 0.13 Ohms (which is not that different to what I got on the good ones)

So what gives? Why is its value so close to the good ones?

Also I note this atlas esr meter with give capacitance as well as low esr, but it states that sometimes it cant calculate capacitance in circuit. I notice when testing the above capacitor it says *in curcuit* in place of the capacitance reading, EVEN when I have pulled the cap out of the circuit.

Why would that be?

Puzzled...

-Al

[BigAlNZ]

Re: Atlas ESR60 - Low ESR Meter

PPS: I also note that when I tested this VRM cap in circuit the ESR value was 0 but asume thats because of other caps on the mobo which may be in parallel with it (though it wasnt in a line of caps).

-Al

[Wizard]

Re: Atlas ESR60 - Low ESR Meter

I'll ask you to measure the voltage output on that esr tester, should be below diode breakover point (around .45V max) and what KHz esr generates, for that case, you need scope. The standard to compare against is bob parker's ESR meter as your measurements sounds odd.

Cheers, Wizard

[BigAlNZ]

Re: Atlas ESR60 - Low ESR Meter

Hi Wizard,

I will do that. It says in the manual the output is 100Khz.

Interestingly I found the spec sheet for that OST, RLS series 6.3v 1500uf cap. The spec sheet says it should have ESR of about 0.02. Thus if its reading 0.13 it is about 7 times over its rated ESR...

Do I need to open this meter up to measure the output voltage?

[BigAlNZ]

Re: Atlas ESR60 - Low ESR Meter

I'll ask you to measure the voltage output on that esr tester, should be below diode breakover point (around .45V max) and what KHz esr generates, for that case, you need scope. The standard to compare against is bob parker's ESR meter as your measurements sounds odd.

Cheers, Wizard

PS: Whats your method for measuring with scope? I tried with the ESR meter connected to the probe and gnd clip, but when I press the test button the meter says open circuit or low capacitance so I am not sure if its putting the signal out?

-Al

[Wizard]

Re: Atlas ESR60 - Low ESR Meter

ESR meter is constantly outputting when on. All you wanted is to measure peak voltages.

I could not find what I'm looking for, but bob parker said train of pulses at 500uS.

Cheers, Wizard

[BigAlNZ]

Re: Atlas ESR60 - Low ESR Meter

ESR meter is constantly outputting when on. All you wanted is to measure peak voltages.

I could not find what I'm looking for, but bob parker said train of pulses at 500uS.

Cheers, Wizard

Okay, but the method in terms of connecting probe to ESR clip, and GND on probe to other ESR clip sounds right?

Cheers

-Al

[Wizard]

Re: Atlas ESR60 - Low ESR Meter

yes as long as it is isolated power or on battery power.

Cheers, Wizard

[BigAlNZ]

Re: Atlas ESR60 - Low ESR Meter

yes as long as it is isolated power or on battery power.

Cheers, Wizard

OK, will have another go tonight. It wasnt a very thorough attempt at 6am this morning!

Also I have been told that a increase in ESR from the spec sheet value of 2x-10x is typical of a cap thats gone bad. Sounds about right?

IF this rule is true, then looking at the spec sheet tells me the ESR should be 0.023/0.038/0.041 (depending on the size) (spec sheet @ )

Now the cap I have is measuring 0.14 - easily more than twice the above values, and thus the cap is bad...IF the 2x-10x rule is true?

-Al

[severach]

Re: Atlas ESR60 - Low ESR Meter

There is nothing wrong with the measurements. I've measured a lot of popped caps with my Atlas ESR60 where the ESR is decent and the uF is double or triple. I think it's a just a failure mode of some capacitors before they crash and burn.

To duplicate what you see I tested a 820uf cap with a 1 ohm resistor in parallel. The ESR was still 0.06 but Atlas said it was in circuit. There are other strange messages you can coax out of the Atlas with other resistance values.

While the Atlas ESR60 is a nice meter I always reach for the Bob Parker unit when troubleshooting boards since it is so much easier to use. I use the Atlas to test pulls to discard them if the capacitance is too much.

[i4004]

Re: Atlas ESR60 - Low ESR Meter

>Now the cap I have is measuring 0.14 - easily more than twice the above values, and thus the cap is bad...IF the 2x-10x rule is true?

there's no such rule: when cap will make problems for mobo depends on the mobo design.

ie it wouldn't be surprising to learn that mobo was actually working, but as severach says, those caps might just be on the cliff after which they'll burn the mobo too...

in other words, you can have venting cap, and everything works fine. then suddenly mobo doesn't work anymore...
and then one wonders was it increased capacitance that killed it rather than esr...heh...or just cap going short circuit...which is more likely...

either way that is advantage of being able to measure both capacitance and esr...