ESR readings

[davg]

Just purchased an ESR meter and now I need to learn how to use it. I have done some reading but I cannot find if it is necessary to have the mb powered up when taking a reading or not. Is there a rule of thumb to follow to determine if a cap is good or bad.

[lucky13]

Re: ESR readings

You take readings with the mobo off!

You take the reading and write it down. Go look up the specs of it and see if it is within the range.

BTW, which meter did you get?

[Per Hansson]

Re: ESR readings

And you take readings with the capacitor discharged

[davg]

Re: ESR readings

You take readings with the mobo off!

You take the reading and write it down. Go look up the specs of it and see if it is within the range.

BTW, which meter did you get?

Thanks lucky I picked up a cheep analog meter mul 3333 so it is difficult to get an accurate reading that's why I was asking if there was a rule of thumb. When I put the leads across a cap it shoots all the way to the right as if it were a short and I believe I read that is indication that the cap is good??

[Toasty]

Re: ESR readings

>>When I put the leads across a cap it shoots all the way to the right as if it were a short and I believe I read that is indication that the cap is good??<<

"Basically" a correct assumption.

For the caps we are usually dealing with, motherboard VRM and power supply filtering, that meter is really not sensitive enough. The typical caps in these applications would read <.01-.02 ohms. Your meter pegging full right "approximately" indicates a good cap. However, I doubt you can tell the difference from a .08 ohm (bad cap) reading to .02 (good cap).

Even if the meter were 100X more sensitive, with that scale reading 1 ohms max, it still might not be able to discern the good from the bad in the caps we typically deal with here. It would have to be 1000X more sensitive to be able to discover the bad .08 ohm cap. That means full left on the meter would START at 0.1 ohm.

The digital meters are truly the way to go. I use the Blue Meter, which gives a me a resolution of .01 ohm.

Your meter would be okay for those repairs where super-low ESR caps are not used.

Power to the unit under test MUST be off and any caps should be drained either by using a resistor to bleed them down or the "cheating" method of shorting them with a jumper (or tool). Regardless, you should check the cap with a voltmeter first to ensure it is discharged.

Toast

EDIT: My advice would be to return that unit if you are seriously going to be working on computer and video related equipment. Save your bucks and buy the Anatek Blue ESR Meter.

[lucky13]

Re: ESR readings

Thanks lucky I picked up a cheep analog meter mul 3333 so it is difficult to get an accurate reading that's why I was asking if there was a rule of thumb. When I put the leads across a cap it shoots all the way to the right as if it were a short and I believe I read that is indication that the cap is good??

Wow, that looks like one el-cheapo meter.

Seriously, the resolution is too lousy to make any sense of good/bad.

Listen to Toasty and get yourself the Anatek Blue ESR Meter. That should be my next tools purchase once I work myself out of this funk I am currently in. Getting beat up by all sorts of "issues" when I was hoping to be "lucky" and get some quickie jobs done....

[davg]

Re: ESR readings

Thanks all just my luck to buy something no good but I did see in here where homemade meters were being used to determine good or bad caps and I was hoping this would do the job for me. No return policy? Shoot!

[Toasty]

Re: ESR readings

MAT Electronics - 14 Day return policy

http://www.matelectronics.com/Policies.html

Bought on Credit Card? Contact CC issuer. CC policies prevail over store/merchant. Store "works" for them.

Toast

[davg]

Re: ESR readings

MAT Electronics - 14 Day return policy

http://www.matelectronics.com/Policies.html

Bought on Credit Card? Contact CC issuer. CC policies prevail over store/merchant. Store "works" for them.

Toast

Thanks Toasty I tried to return it today to the local supplier I purchased it from but I was told it was a special order and non returnable and since I did ask them to order it for me without checking the scale I did not give them any hassle. I will try to re sale it or find a use for it.

[Toasty]

Re: ESR readings

Okay. It wasn't a direct purchase then.

Curiosity - Is there a schematic of the meter in the manual?

Hope you go Blue soon!

Cheers!
Toast

[davg]

Re: ESR readings

Okay. It wasn't a direct purchase then.

Curiosity - Is there a schematic of the meter in the manual?

Hope you go Blue soon!

Cheers!
Toast

The manual was a single sheet of paper with just a few words saying to add batteries (in poor English).

[i4004]

Re: ESR readings

davg, while that's certainly not the best resolution even for analog meter, you can still use magnifying glass and a known good cap to see if you can establish difference between good and bad ones.
mark where does good cap place a needle and then comapre to some known badcaps...
mobos that work ok have ok caps(so you have a way to distinguish good from bad). also, most of the time badcaps are visibly bulging.

also, view such comments
"08 ohm (bad cap) reading to .02 (good cap). "
with scepticism.

there's no such precise disctinction that 0.08 is a bad cap and 0.02 is a good cap.
at some systems(cpu and mobo architectures) 0.1 may be ok, at others not, but you probably can see 0.1 vs. 0.0 difference on that meter, if with lil help from practices i mentioned above(hard to say as i can't see the size of that thing).

read the "Sample ESR Readings" chapter from here
http://www.capacitorlab.com/esr-meter/index.htm
(and following chapter)
and from that perspective maybe your analog meter is usable.
either way, i encourage you to play with it and see if you can find it usable.(find some dead mobos(of types you intend to fix), get some new caps and measure etc.)
don't discard it that easilly...

i have analog meter myself (though it has a bit more stretched scale on 0-3ohm range than yours) and i can detect pretty damn small esr differences.
usually i don't even need a good low esr cap to measure against.
as badcaps are usually pretty obvious.

[Toasty]

Re: ESR readings

>>The manual was a single sheet of paper with just a few words saying to add batteries (in poor English).<<

Shame. I was hoping to see if you could modify the meter to at least get better sensitivity out of it.

Toast

[Solder Boy]

Re: ESR readings

I gotta put my 0.02 cents worth here. There really isn't anything wrong with the meter you purchased. For $60 it's been a godsend to me.

For the amount of motherboards I repair spending upwards to $300 on a " good" ESR meter didn't make much economic sense to me.

Thanks to this ESR meter I have repaired mobos that were previously declared dead. And a friend of mine who has well over 20 yrs experience repairing electronics, wonders what he did without it.

The meter you bought isn't junk.

[Toasty]

Re: ESR readings

>>...spending upwards to $300 on a " good" ESR meter...<<<

Blue Anatek is $79 in kit and $109 pre-built

The unit is not sensitive enough to detect marginal caps that we commonly work with and discuss here. As in my example, a cap that is spec'd to .02 ohms and is actually .08 ohms will not be discernible on this meter. If the cap has failed and gone to .25 ohm or higher, then it would be obvious with this meter there is a problem.

The meter is good for the standard/common caps and non-low ESR types. Yes, I'm sure it will detect its fair share of obvious failures. But, the marginal failures will be missed.

Toast

http://www.anatekcorp.com/blueesr.htm

[davg]

Re: ESR readings

>>The manual was a single sheet of paper with just a few words saying to add batteries (in poor English).<<

Shame. I was hoping to see if you could modify the meter to at least get better sensitivity out of it.

Toast

So how can it be made more sensitive? And discharging the cap, is this done to protect the meter or will it effect the reading?

[Toasty]

Re: ESR readings

Not being familiar with your meter, I do not know. That's why I had hoped for a schematic.

Discharging is done to protect the meter.

Toast

[i4004]

Re: ESR readings

>So how can it be made more sensitive?

wikipedia article on esr should link to at least 2 diy analog meter projects, and both should provide info on how to stretch the scale, if not on the web sites, then by contacting authors...

[lucky13]

Re: ESR readings

So how can it be made more sensitive? And discharging the cap, is this done to protect the meter or will it effect the reading?

The sensitivity is determined by the circuit driving the analog meter. Unless you open it up and reverse engineer it to see if you can perhaps add an op-amp circuit to multiply the driving signal for the meter, otherwise there is no hope.

Think like signal amplifier to pull in those far away signal. It is not easy to do.

It is much easier to attenuate a signal that is too strong.

[i4004]

Re: ESR readings

http://cgi.ebay.com/In-circuit-Capac...86.c0.m14#shId