[Test-Equipment] ESR meter reviews

[Carl]

----- Original Message ----- 
From: "Richard Knoppow" <dickburk at ix.netcom.com>
To: "Discussion of Electronic Test Equipment" 
<test-equipment at mailman.qth.net>
Sent: Monday, June 27, 2011 6:42 PM
Subject: Re: [Test-Equipment] ESR meter reviews


>
> ----- Original Message ----- 
> From: <bonddaleena at aol.com>
> To: <TekScopes at yahoogroups.com>;
> <test-equipment at mailman.qth.net>
> Sent: Monday, June 27, 2011 3:07 PM
> Subject: [Test-Equipment] ESR meter reviews
>
>
>>
>>
>>
>> Hi. As a long time ham and restorer of older radios and
>> test equipment, I have always been aware of capacitor
>> failures. This started when I was an Engineer with IBM and
>> did failure analysis on circuit boards. This discussion
>> will focus only on electrolytic caps.
>> Since then, I have found 'buckets' full of bad caps in all
>> vintages of equipment.
>> I now own 3 quite different ESR meters and thought I'd
>> share the info with you folks. All 3 have good/not so good
>> points.
>> First an important caveat that even very experienced techs
>> overlook....
>>
>> The use of a small, DVM style cap 'tester' will tell you
>> nothing about leakage or ESR. They are great for finding
>> VALUE.
>> You can find a comparison of the following meters on the
>> AnaTek website.
>>
>> My meters:
>>
>> Mat Electronics Model MUL3333. This was my first ESR
>> meter. It's analog and cheap, er, inexpensive. ha ha
>>
>> Pros:
>> works OK
>> inexpensive
>>
>> Cons:
>> scale too compressed at low resistance end
>> " makes it difficult to find shorts
>>
>> Observations:
>> I believe this meter got a bum rap in the AnaTek 'review'
>> because of a broken battery contact. I have had no such
>> problems in 2 years.
>> The 'overly compressed scale' situation, is easily
>> rectified by putting an inexpensive DVM (with a buzzer
>> function) in parallel with the MUL3333. This easily senses
>> the difference between a short and a low value ESR cap.
>> This does make for a bulky combo.....
>>
>> Peak ESR 60
>>
>> This was my second purchase. Kind of a strange shape
>> factor but that doesn't really matter.
>>
>> Pros:
>> Works SUPER
>> Gives you cap 'values'  (out of crcuit) + ESR
>> Automatically discharges small (!) caps. It won't bleed
>> down your linear amps caps!
>>
>> Cons:
>> Clumsy to use, due to it's need to 'restart' constantly
>> (see Observations for more info)
>> Small alligator clips with short leads
>> Can't go from cap-to-cap quickly
>> High $
>>
>> Observations:
>> At first, I thought the constant need to restart the
>> device was a major disadvantage. However, I have come to
>> learn that in it's 'start up' routine, it checks for
>> charged caps and discharges them,
>> I built a small aluminum stand to prop it up for easier
>> viewing.
>> I notice Peak has a newer model
>>
>> EVB Esr meter
>>
>> Just got this one
>>
>> Pros:
>> Simple to use
>> Well made
>> Beautiful display
>> Vitor (seller in Portugal) is a great guy! I have NO
>> connection with him
>> Based on the proven Dick Smith design
>> Has handy chart on front of meter (ballpark numbers)
>>
>> Cons:
>>
>> Comes without test leads. (no biggie)
>> Awful redesign of the power/calibrate switch! This has
>> been documented by several other users as well. Mine
>> failed in the first 10 minutes of use.
>>
>> Observations:
>> If you look at the EVB site and download the Manual, you
>> will see what the above switch USED to look like. Now, you
>> have to press on the hard plastic front face. This in turn
>> pushes on a plunger, that connects to a small switch on
>> the PC board.
>> I replaced this setup with a Radio Shack mini switch that
>> is the exact duplicate of the original design. Works
>> great!!
>>
>> These observations MAY also hold true for the "Blue ESR
>> Meter". The blue model comes with permanently attached
>> test leads. I actually prefer the EVB setup better, I just
>> wish I had known about the 'no leads included' up front.
>> Again, no biggie.
>>
>> As you can see, all devices have their +/- aspects. I
>> believe the EVB will become my favorite..............
>>
>> ron
>> N4UE
>>
>     My only comment is that many caps will test OK for ESR
> and value but have low parallel resistance, AKA, leakage.
> ESR testers usually don't test for this. High leakage is a
> common problem with electrolytic caps because they tend to
> have high leakage even when new, but it _can_ be a problem
> with other types of caps. I've found paper and even plastic
> caps which test OK on an impedance bridge but don't work in
> the circuit. The reason; high leakage.
>     I have two methods of testing because I don't have a
> special instrument for making the measurement. I either use
> a small adjustable power supply and a meter capable of
> reading micro-amps, or a General Radio megohmeter. The later
> works fine but has a fixed test voltage of 500V, too high
> for many caps. To use the power supply, I simply hook up the
> cap and meter in series. Thsi particular supply has current
> limiting but a series resistor might be a precaution
> otherwise. I bring the voltage up to the rated voltage while
> watching the amp meter. If the cap is nearly shorted it
> shows up right away and I can shut down the supply.
> Otherwise I bring it up and leave it at the rated voltage
> while watching the meter. For paper, or film caps the
> current should be no more than about 5 uAmps. Modern film
> caps have such low leakage its hard to detect.  I use a
> Tektronix DMM which has enough sensitivity. For
> electrolytics the dielectric layer may take some time to
> form. If its been used recently the dielectric should be OK
> but a cap that's been out of service for some time may take
> half an hour or more to form. Set the voltage at a moderate
> level and watch the current. It should go down with time and
> if it does raise the voltage to the rated voltage in steps.
> A good electrolitic cap should have leakage current of no
> more than about 15 uAmps and it should not rise as the cap
> runs. Again, normal ESR or capacitance bridges may not
> measure electrolytics correctly because they do not bias the
> cap. Without bias the dielectric layer may not be completely
> formed which will affect both value and leakage.
>
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com


For SS voltage caps I use an Anatek Blue which does the job.

For tube gear I dont even bother checking 40-80 year old 'lytics, they get 
replaced as doones in  most SS supplies that are over 30 years old.

A big problem these days is mica and some HV ceramic caps showing leakage. 
Silvered ceramic and mica trimmers are another source of trouble. You need 
to test these at or near their working voltage.
Sprague made a series of excellent cap testers from the 1939 Model 16 to the 
60's TC-6A. The military ZM-11 is another good one. I have the 3 above and 
use the 16 a lot since it will adjust from 0 to 1000V and has caused me to 
trash many NOS mica caps. Naturally it had to be rebuilt first!

Carl
KM1H