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ESR meter. Just do it.

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I've finally ordered a "blue esr meter" kit. An esr meter has been on the want list for some time. I had it built and testing known good parts within two evenings. Last night I had a chance to really use it. The results are outstanding. In a past life I went to school for electronics(I've forgot more than I know). There was no mention of the awesome ESR meter that I can recall.

I have a small amp on the bench that was difficult to find so I took a chance. Advertised as "works great" and the price was low enough for the worst case. I was planning to rebuild it into reliable anyhow. I think they just powered it up, saw an led light and it was deemed good.

I found a hot looking area in the power supply section on the board before I powered it on. I immediately put this meter to work. I checked the worst looking cap and it was open. Checked more caps to get a "feel" of it and found another open cap. Some of the others were up to nearly 30 ohms. The entire load of caps was checked in ~10min.
I popped a couple of them out of circuit to test again and they are indeed bad. They measure the same out of circuit. All of the capacitors are toast aside from two.

Without even powering it on, the esr meter can tell us that it would be a mircacle if it passed signal. Only one cap actually looked bad. She will get some new high temp caps and I will go from there.
 
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One thing to be careful of is to make sure the caps being tested are discharged or you can wreck the IC. On the blue meter it can be replaced.

There is a brand from the UK for more money that has a circuit that automatically discharges caps if you forget.

http://www.peakelec.co.uk/acatalog/jz_esr60.html

You can buy better leads for all of them optionally.
 
Fact is, much of my service work takes place without powering the unit: in-circuit measurements to find out what's going on without making smoke. IMO, you're on the right path! There's more to consider than just esr, but it's one of the most telling things you can do quickly and in-circuit.
 
I have a DIY esr meter and it's been very useful. As Conrad says, it's not the only test but it can be very telling. If the ESR is high or the cap is open, you need go no further with that one.

I built this one. It's pretty simple and I made it almost completely from my junk box.
http://ludens.cl/Electron/esr/esr.html

Have fun with it,
John
 
Don't get "fooled!"

A SHORTED cap. MAY look "real good" on an ESR meter (VERY low Resistance) but is still BAD! :sigh:

Check ANY caps. that kind of "look too good" with a conventional Ohm meter to check for shorts (some people use a "double lead" system, two leads to the ESR meter, two to the multi meter).

When I built my "Dick Smith" ESR meter, I opted for the "protection kit" that could be added later. :thmbsp:

No test can find all problems, but at least you got the "bad ones" out for more testing, replacing ALL old electrolytic caps. is the best thing for long term reliability. :yes:

Mark T. :music:
 
grey said:
I've finally ordered a "blue esr meter" kit. An esr meter has been on the want list for some time. I had it built and testing known good parts within two evenings. Last night I had a chance to really use it. The results are outstanding. In a past life I went to school for electronics(I've forgot more than I know). There was no mention of the awesome ESR meter that I can recall.

I have a small amp on the bench that was difficult to find so I took a chance. Advertised as "works great" and the price was low enough for the worst case. I was planning to rebuild it into reliable anyhow. I think they just powered it up, saw an led light and it was deemed good.

I found a hot looking area in the power supply section on the board before I powered it on. I immediately put this meter to work. I checked the worst looking cap and it was open. Checked more caps to get a "feel" of it and found another open cap. Some of the others were up to nearly 30 ohms. The entire load of caps was checked in ~10min.
I popped a couple of them out of circuit to test again and they are indeed bad. They measure the same out of circuit. All of the capacitors are toast aside from two.

Without even powering it on, the esr meter can tell us that it would be a mircacle if it passed signal. Only one cap actually looked bad. She will get some new high temp caps and I will go from there.
Click to expand...

Nice. I can't live without my ESR meter besides me... for it's fast convenience diagnosis. Just remember to discharge any large caps before putting the test wires hehe. Even if I know that, I've toasted 2-3 times the fuse resistor inside mine... so a something like 50 ohms 10W resistor handy is a must :)
 
markn2wae said:
A SHORTED cap. MAY look "real good" on an ESR meter (VERY low Resistance) but is still BAD! :sigh:
Click to expand...

True enough. I usually make the VOM resistance scale check afterwards if they all check "ok", just to be sure. I want to see it climb as the cap charges.

Thanks for mentioning it.
John
 
I presume y'all know that ESR varies with frequency. What frequency does the "Blue" ESR meter use? Many use 1 kHz. But that's just one data point among many possible data points over the audible frequency range we all have an interest in.

One of the best pictures you can get of a cap's performance is obtained with a Woofer tester. The WT2, made by Smith & Larson Audio can also test Inductors and resistors. You pick how many data points you want over a 10-20,000 hz range and run a scan. WT2 plots impedance and phase and spits out a detail data table that includes ESR and D.F. Visit here for more info on the WT2 tests on some good and bad speaker caps. Start at Post #4 and download the pdf files. http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=6354
 
spkrdtr said:
One of the best pictures you can get of a cap's performance is obtained with a Woofer tester.
Click to expand...

I've been thinking of buying the Smith & Larson system. A friend has the WT from Parts Express and he recommended that I buy the S&L version. Maybe this is the impetus I need to do it.

Thanks,
John
 
The blue meter and many similar meters are intended to be a quick and portable go/no go tool. Someone scoped it at a 2 kHz 8 uS pulse. The standard when I was looking was 1k and the more expensive units had a selection for 100Hz. I can only vouch that it did the job fast in circuit and weeded out the go/no go units as it should for this example. I did go through checking for voltage first and I have a "100 ohm resistor on a stick" handy if anything needs discharging. If I had to do this all day I would probably choose a meter with a discharging feature like the Peak.

The WT2 is certainly nice to have and not a gross investment. I'm not sure that that it would replace this meter however. I have a very basic understanding of both so please understand that I'm just curious here. Have you tried to use it in circuit the same way you would use the esr meter?

I have a Linearx LMS system that should use the same testing modes as the WT2 for RLC. I will check out the results of both the LMS and esr the next time I have it set up. I do have some certainty that the LMS and a dedicated LC meter would unnecessarily redundant. It's a valuable tool for a long list of things as you already know.
 
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Both units sold by PE have had issues. Strongly suggest you go with the WT2. That system also has great tech service.


nerdorama said:
I've been thinking of buying the Smith & Larson system. A friend has the WT from Parts Express and he recommended that I buy the S&L version. Maybe this is the impetus I need to do it.

Thanks,
John
Click to expand...
 
I have used the unit in circuit and it works fine.

grey said:
The blue meter and many similar meters are intended to be a quick and portable go/no go tool. Someone scoped it at a 2 kHz 8 uS pulse. The standard when I was looking was 1k and the more expensive units had a selection for 100Hz. I can only vouch that it did the job fast in circuit and weeded out the go/no go units as it should for this example. I did go through checking for voltage first and I have a "100 ohm resistor on a stick" handy if anything needs discharging. If I had to do this all day I would probably choose a meter with a discharging feature like the Peak.

The WT2 is certainly nice to have and not a gross investment. I'm not sure that that it would replace this meter however. I have a very basic understanding of both so please understand that I'm just curious here. Have you tried to use it in circuit the same way you would use the esr meter?

I have a Linearx LMS system that should use the same testing modes as the WT2 for RLC. I will check out the results of both the LMS and esr the next time I have it set up. I do have some certainty that the LMS and a dedicated LC meter would unnecessarily redundant. It's a valuable tool for a long list of things as you already know.
Click to expand...
 
ESR doesn't vary with frequency, by definition. Total impedance falls with increasing frequency, until capacitive reactance falls below ESR and/or inductive reactance. Electrolytic capacitor ESR is measured and specified at 100KHz (sinewave) by manufacturers, because total impedance at this frequency is generally dominated by ESR. Pulse measurements should correlate with those from a 100KHz impedance bridge as long as the ESR meter is designed to ignore inductive effects around the leading edge of the pulse. Fortunately, that's a fairly easy thing for engineers to accomplish.
 
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I've got a Creative Labs ESR meter and it measures at either 50 KHz or 100kHz...depends on the year it was made. (The earlier versions were at 100K but their literature said it was dropped to 50kHz because the IC they changed to wasn't stable at 100k, I'm not sure what version mine is--never bothered to put it on the frequency counter)
 
I found some nice pointy probes for mine, that let me get to the capacitor leads from above. I can test all on a board in a few minutes, put a dot on each bad one with a marker as I go, replace those as needed.

esrmeter-testing.jpg
 
Thanks ED. I looked at some tweezers beforehand. That seemed to be the best route for most testing. I do not recall, but they may be a Kelvin type. Where did you find yours? These look more flexible.


spkrdtr said:
I have used the unit in circuit and it works fine.
Click to expand...

Sweet. I will try to get more time in with the LMS this winter.
 
grey said:
Thanks ED. I looked at some tweezers beforehand. That seemed to be the best route for most testing. I do not recall, but they may be a Kelvin type. Where did you find yours? These look more flexible.
Click to expand...
I bought those probably 6-7 years ago, seller long forgotten, don't see anything exactly with a quick search but these look promising. Mine were straight tips too I bent in a little. No affiliation... I know nothing!
 
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