Regular multimeter to test for ESR?

[volto]

Hi, I'm new here. I'm in no way an electronics guru, or even somewhat adept, but I've already fixed a few power supplies and LCD monitors by swapping the bad capacitors. I've just replaced them all, and I would rather have a way to test before unsoldering and replacing them, or to test new capacitors to make sure they fit the bill. Ive looked around some and it seems ESR meters are either too expensive or you have to build them yourself, and I don't have the time or experience to do that. I was wondering if something like this would do the trick for measuring ESR, a regular Ohm meter, says it measures down to 0.01 ohms, but is that the same as ESR? TIA.

[i4004]

Re: Regular multimeter to test for ESR?

no, esr is measured via ac.

that thing won't do.

[PCBONEZ]

Re: Regular multimeter to test for ESR?

The simple explanation is that ESR is 'like' resistance, only at a frequency.
ESR meters measure by injecting a 100kHz signal (usually, 100kHz is the standard) and measuring what happens to it.
Regular ohm meters inject plain DC volts and won't work to check ESR.

.

[PCBONEZ]

Re: Regular multimeter to test for ESR?

*IF* there are no other capacitors in parallel you can check ESR in circuit with the correct kind of meter.
-
I built mine from one of those kits.
It's very easy and doesn't take that long.

.

[starfury1]

Re: Regular multimeter to test for ESR?

yeah as above re multimeter
best way ESR meter either a kit or pre made unit OF "quality"
but yes not that cheap

if you search the net you will find cheaper ways to build something but accuracy probably wont be that good.
Adapters for multimeter's and using microamp meter movements

but its possibly better then nothing as when ESR goes it usually goes big time.
So somewhat treat them as a "go no go"

also depending on circuits there can be some traps with in circuit testing

Since caps don't cost the earth thats probably the simple quickest way
it (mostly) wont hurt anyway.

ESR meters, they are handy to have but you can get away without them if you only do it occasionally

you will get to know which caps are most likely to fail, like DC output in PSU and VRM on MB

Having a multimeter and knowing how to use it with some basic knowledge of electronics is a must I think for trouble shooting

theres a few threads on esr meters around here.

HTH

Cheers

[i4004]

Re: Regular multimeter to test for ESR?

if you search the net you will find cheaper ways to build something but accuracy probably wont be that good.

why not?
scale is pretty strecthed on lower ohm values, so i don't see any way a digital-readout mater would be better.
as you said esr is pretty high when it becomes problematic so 0.0x doesn't mean much, and 0.1ohm you can easilly measure with analog diy meter.

So somewhat treat them as a "go no go"

not at all.
the only thing limiting their accuracy is one's willingness to calibrate them with precision that is needed, ie using few resistors with small values and marking the scale.

so i would say these are not inferior to expensive meters at all(i think you mostly pay for that digital readout..heh).

those who think they are can send me some badcaps they measured with their digital meters, and i'll measure them with my meter so we can compare the results.
i believe discrepancies will be minor and irrelevant.
(PM me and i'll give you my address)

[volto]

Re: Regular multimeter to test for ESR?

Thanks for all the info. I will look through the many esr meter threads, i'd like to spend less than $50 on one, or less than 5 hours building one. That might not be possible tho.

[willawake]

Re: Regular multimeter to test for ESR?

i would get this one http://www.anatekcorp.com/blueesr.htm
but i like expensive tools

[volto]

Re: Regular multimeter to test for ESR?

Certainly tempting. I just don't know if I can justify spending $80 on it...

[PCBONEZ]

Re: Regular multimeter to test for ESR?

Their use is to find out if caps that are not bloated or are in question for some other reason are bad or not.
- If they are bloated then you KNOW they are bad anyway. No need for a meter.
- If they are a crap brand and the board is misbehaving just replace the caps. No need for a meter.

Other than just curiosity checks the time a meter helps is when you have all good brands, nothing is bloated, and the board is unstable.
-
If that doesn't come up that often in what ever it is you do then you don't really need a meter.

NICE to have one when it does come up though.

.

[volto]

Re: Regular multimeter to test for ESR?

Yeah. Every once in a while the power supply in one of my computers goes BZZZZZZZ, and sometimes it shuts off while its buzzing, other times, it just buzzes for a while and doesn't turn off. I looked at the caps and none of them look bad, but I might just replace them all anyway.

Under further investigation, the noise seems to be coming from my UPS, but nothing else connected to it turns off. I dont know, it doesn't happen often enough or long enough to quickly pinpoint exactly where the sound is coming from.

[PCBONEZ]

Re: Regular multimeter to test for ESR?

Caps (among other things) go bad in USP units too.
-
With the way you describe it it may be fluctuations from the power company and not your gear at all.

Keep about a 2 foot piece of small diameter tubing handy.
It makes a great stethoscope when you don't know where a noise is coming from.
With one end of the tube in your ear just touch both boxes with the other end and see which one is loudest.
[Sounds hokey but it works very well.]
.

[starfury1]

Re: Regular multimeter to test for ESR?

i4004
The statements above are "broadly" speaking since he did mention he wasn't going to spent the earth on one (not that you really need to)

I was thinking more along the lines of salvaged parts to build one for cheap
(note that if you happen on a good size, quality meter you could end up with a good unit)

Basically you are talking small orders with low ESR and that mostly what you would be liable to be measuring so cap A and cap B would probably be fairly close

Contact resistance may play a bigger part.
(a point to watch out for)

True if you find a good design, build it with a good meter and Calibrate it you could get an accurate Analogue Unit

the "go no go" was in ref to the fact that normally the ESR goes thorough the roof
( from what I understand)

even something that is somewhat inaccurate would be better then nothing
and yes its only up to you how far you want to take it,
but to tweak something does require an understanding of how it operates.

one important thing is to play with it and measure known good caps and some bad ones to get a good feel of were things lay.

anyway you will find some links off this page volto, I haven't build any so don't have a clue on these.

http://octopus.freeyellow.com/esr.html

BTW I think there was a post on using a CRO for measuring ESR...

99 cent ESR meter

http://octopus.freeyellow.com/99.html

Hope that clears that up and yes I agree, given the right stuff, & tweaks you could build a very accurate analogue meter.


HTH

Cheers

[i4004]

Re: Regular multimeter to test for ESR?

but to tweak something does require an understanding of how it operates.

one important thing is to play with it and measure known good caps and some bad ones to get a good feel of were things lay.

to tweak it, you only need few ressitors of low value, like i said.
resistance of resistor at measuring freq. is same thing esr is.
1 ohm resistor is same value(and same readout on analog instrument) as badcap with esr of 1 ohm.

with due respect to bob parker i dunno why he failed to build decent analog meter, as he says
"After a few fairly unsuccessful attempts at designing an ESR meter around analog circuitry, I realized that this was an ideal application to take advantage of the speed and versatility of a Zilog Z86E0408 microcontroller".
http://www.anatekcorp.com/testequipment/esrtext.htm

microcontroller for measuring just the resistance at xx khz? seems like overkill to me.

to say measuring esr needs to be expensive is but a nonsense to me. it needs to be cheap so more people can do it. having such overkill/overpriced instruments is making people like volto stay away.

to that extent, here's one more cheap analog design:
http://members.shaw.ca/swstuff/esrmeter.html
total cost of components is about 22€ (about 30$) here(in usa it should be much cheaper), with batteries.

as for 99cent meter, i doubt volto has a scope...

[starfury1]

Re: Regular multimeter to test for ESR?

"tweak" as in possibly modify circuit

"calibrate" resistors, agree

to say measuring esr needs to be expensive is but a nonsense to me. it needs to be cheap so more people can do it. having such overkill/overpriced instruments is making people like volto stay away.

Agree,
but I dont think anyone said it "needs" to be, just that pre-made units tend to be...take a look at the cap wizards price and thats analogue meter (dont know what the circuit is thought)

Yes with a bit of scavenging and a circuit you can build one for cheap
all I was really driving at was for the low ESR caps you may need to optimize it.."not as accurate" depending on what circuit and what you build it with

It was a general statement

on the Cro ,
very much doubt he has
The question was asked in another thread so thought Id make mention on it

There are 1 or 2 or more threads on ESR meters and circuits going in the test eq section I think
(which I made ref to above)


so I was just trying to keep it brief here

probably should have put a link to them, here's one for starters...there are a few from a quick look

https://www.badcaps.net/forum/showthread.php?t=2478

there is also a thread I posted a lot of links in but cant find it now
(including the links above)


BTW I4004 if you don't mind what is the unit you got, as in which circuit did you use?


Cheers

[Bob Parker]

Re: Regular multimeter to test for ESR?

with due respect to bob parker i dunno why he failed to build decent analog meter, as he says
"After a few fairly unsuccessful attempts at designing an ESR meter around analog circuitry, I realized that this was an ideal application to take advantage of the speed and versatility of a Zilog Z86E0408 microcontroller".
http://www.anatekcorp.com/testequipment/esrtext.htm

microcontroller for measuring just the resistance at xx khz? seems like overkill to me.

to say measuring esr needs to be expensive is but a nonsense to me. it needs to be cheap so more people can do it. having such overkill/overpriced instruments is making people like volto stay away.

I was trying to keep the circuitry very simple - too simple. Remember that this was back in 1995. I didn't have an internet connection and I didn't have lots of other people's designs to get ideas from like everyone's got now. I had to find my own way.

The microcontroller allows it to have digital displays. Drop an ESR meter with an analog meter movement off a repair bench and you'd be lucky if it still works. LED displays don't have that problem.

Also the microcontroller allows it to automatically switch between ranges to always have best resolution, and to turn itself off if it's idle.

Finally .... the ESR meter I designed was intended for professional repair people, not hobbyists. To someone making a living from doing repairs, they can often make back the price of an ESR meter (of any kind) in just one or two days, from the time it can save in tracking down the causes of faults and getting more paying jobs done. The economics of professional electronics repair are completely different to students etc who just want to fix their misbehaving motherboards.

I agree that it's not necessary to spend a lot of money to measure capacitor ESR. There are quite a lot of simple designs which drive analog meters on the net, which would easily identify bad caps. High accuracy isn't needed because ESR has to rise to a very high value to cause problems in almost all circuits.

[i4004]

Re: Regular multimeter to test for ESR?

"tweak" as in possibly modify circuit

ah, that.
well it's easy enough to ask for help from maker of the design.
or me, for that matter, as i can tell you about usual mods for these 2 designs, if need be.

but I dont think anyone said it "needs" to be, just that pre-made units tend to be...take a look at the cap wizards price and thats analogue meter (dont know what the circuit is thought)

probably these(like any esr meter type) don't sell that well, and then they rise the margin to silly values to compensate.
frankly, i dunno would they sell well even if they were on all places were cheap digital multimeters are AND they were very cheap.
many people just wouldn't know what is that.
many people know they need avo-meter and they know how to use it and they do use it etc.
but not many are familiar with esr concept.

heck i think in times before web even most of the electronics repairmen didn't use it/know about it, if there were any esr-meters to buy to begin with.

all I was really driving at was for the low ESR caps you may need to optimize it.."not as accurate" depending on what circuit and what you build it with

it is only "not as accurate" in a same sense any digital meter is to analog meter.

BTW I4004 if you don't mind what is the unit you got, as in which circuit did you use?

https://www.badcaps.net/forum/showthread.php?t=3081

i also got parts for the 30$ version i linked above, but gave up on that: there was a snafu upon ordering it (had to enter components few times to the web-page...not my fault).
and when you build one you kinda don't need one more, so by that time i lost any will to do it.

i sent components to my friend, but it seems it got stuck in the mail. we'll see what happens.

Drop an ESR meter with an analog meter movement off a repair bench and you'd be lucky if it still works. LED displays don't have that problem.

first thing to do when you get an instrument: throw it off the bench and see what happens!

Also the microcontroller allows it to automatically switch between ranges to always have best resolution, and to turn itself off if it's idle.

it was to be expected to see some advertising here..hehe...
btw. the funniest thing is the 'auto-ranging'.
you have that, and i have 0-30ohm scale, and in the end we have same thing.
turn itself off when idle; yes, i'll admit that is one advantage i must acknowledge.
then again i didn't notice leaving my analog meter (accidentally) on for few hrs consumed much of the battery.

Finally .... the ESR meter I designed was intended for professional repair people, not hobbyists. To someone making a living from doing repairs, they can often make back the price of an ESR meter (of any kind) in just one or two days, from the time it can save in tracking down the causes of faults and getting more paying jobs done. The economics of professional electronics repair are completely different to students etc who just want to fix their misbehaving motherboards.

this is completely irrelevant and serves only to justify your (too)high price.
be it "professional" or amateur they can both get the same job done with either of the two designs.
the only real difference is the price.
or, in other words, how much money does somebody want to throw away.
because if somebody loves electronics, i expect he can make a basic project.

something else; i don't put people into "pro" or "hobbyist" categories, because it discards the factor of love and interest towards something, and that is more important than diploma.
(anybody here graduated on 'capacitor university', heh? you just have too many items of interest in todays world, schools can't cover them all, and what's learned wears off rather fast)

esr-meter is for people that want to know esr value, no matter who they are.
it should be cheap so they can easilly find out. if they need it for 10 caps in their whole life, let them buy it for those 10 caps.

about accuracy (because there seems to be a light-motif of this thread to put down capabilities of analog meters);
with my analog meter i can detect a difference between normal(gp) and low-esr capacitor, when they're both new, offcourse.

[Bob Parker]

Re: Regular multimeter to test for ESR?

first thing to do when you get an instrument: throw it off the bench and see what happens!



it was to be expected to see some advertising here..hehe...
then again i didn't notice leaving my analog meter (accidentally) on for few hrs consumed much of the battery.


this is completely irrelevant and serves only to justify your (too)high price.
something else; i don't put people into "pro" or "hobbyist" categories, because it discards the factor of love and interest towards something, and that is more important than diploma..

OK, I understand your attitude. In the 12 years I've been supporting the meter I designed but which others sell, in my own time at my own expense, I've met a few others like you.
I am going to ignore you from now on.

[Spacedye69]

Re: Regular multimeter to test for ESR?

Here is a link to an EVB brand Bob Parker meter review. Price isn't that bad for the kit.

Who's ugly fingers are those in the pic?????

I think I paid about $35 US including shipping when Dick Smith sold out the kits, but I would probably pay $80 for a good kit. Much cheaper than buying an assembled meter from other companies. I use mine quite a bit, so I could justify the cost.

[i4004]

Re: Regular multimeter to test for ESR?

I am going to ignore you from now on.

i can never top that.
i can't ignore human beings.
won't categorize 'em, can't ignore 'em...