ESR Meter Calibration, no manual

[nickBcap]

Hi,
I thought this a good idea and paid the expensive price(for me) for an ESR meter. I took it to a retail shop that specialises in electronics and the boss suggested this ESR meter may need calibration. It is a bit weird, I am sure the battery is ok and swapped it out for a new one too to test new capacitors I bought and initially some gave proper readings on both the ESR and the multi meter but later would not give proper readings.
Looking on YouTube I looked at a video showing how to calibrate "a" ESR meter but it is different to the ESR here and not a lot different.
In the YouTube video the ESR meter is shorted in the testing sockets where the capacitor wires go. However I am not sure which are the holes I should use there or how to adjust the trim pot.
Can anyone suggest how I calibrate the ESR meter?
Or if it is ok to just experiment. Would experimenting cause damage to the 9Volt ESR meter?
Photos coming.

[mariushm]

Re: ESR Meter Calibration, no manual

You should be able to tell if it's accurate or not by shorting the - and + with a small piece of wire (basically a 0 ohm resistor) and then with a 1 ohm 1% or better (or several resistors in parallel to lower resistance value).

I would try to see if there's a calibration menu by shorting - and + while powering the meter. Or keep reset pressed and power on the meter while reset is pressed. Or both short + reset and power on.

Can't think of anything else.

This meter is basically a microcontroller with a 3.58 Mhz oscillator, a LM339 quad comparator, those 3 small transistors or mosfets switching between different current values and a 5v linear regulator near the capacitors.
The display is a 2-3$ one off eBay, it's a standardized display very easy to use with microcontrollers. If there's any calibration data, it's in a EEPROM memory inside the microcontroller, or it's made using that potentiometer by the reset button. The other potentiometer is most likely for LCD display contrast.

[vinceroger69]

Re: ESR Meter Calibration, no manual

pdf in post 6 may help
https://www.badcaps.net/forum/showth...heap+esr+meter

[multimeter]

Re: ESR Meter Calibration, no manual

dont forget ambient temperature will have an effect on capacitors ,the warmer they are the lower there esr value

[nickBcap]

Re: ESR Meter Calibration, no manual

You should be able to tell if it's accurate or not by shorting the - and + with a small piece of wire (basically a 0 ohm resistor) and then with a 1 ohm 1% or better (or several resistors in parallel to lower resistance value).

I would try to see if there's a calibration menu by shorting - and + while powering the meter. Or keep reset pressed and power on the meter while reset is pressed. Or both short + reset and power on.

Can't think of anything else.

This meter is basically a microcontroller with a 3.58 Mhz oscillator, a LM339 quad comparator, those 3 small transistors or mosfets switching between different current values and a 5v linear regulator near the capacitors.
The display is a 2-3$ one off eBay, it's a standardized display very easy to use with microcontrollers. If there's any calibration data, it's in a EEPROM memory inside the microcontroller, or it's made using that potentiometer by the reset button. The other potentiometer is most likely for LCD display contrast.

I shorted the actual battery terminal connections on the board and no calibration feature appeared. I shorted a wire in to the 2 test point sockets and no calibration menu appeared. Thanks for posting ps(I paid probably a sillie, $15) imagining ok this time I am going to pay some dollars for something better

[nickBcap]

Re: ESR Meter Calibration, no manual

pdf in post 6 may help
https://www.badcaps.net/forum/showth...heap+esr+meter

Going to check this out, thank you.

[nickBcap]

Re: ESR Meter Calibration, no manual

dont forget ambient temperature will have an effect on capacitors ,the warmer they are the lower there esr value

Not sure the low temperature differences will have any affect in this situation. I am more asking to find a calibration feature to hopefully correct the seemingly confused state of the ESR Meter.

[mmartell]

Re: ESR Meter Calibration, no manual

You may have used this on a cap that wasn't fully discharged and damaged it. Get your DMM and check the resistors in the vicinity of the test leads and make sure they are good.

[nickBcap]

Re: ESR Meter Calibration, no manual

You may have used this on a cap that wasn't fully discharged and damaged it. Get your DMM and check the resistors in the vicinity of the test leads and make sure they are good.

Hi, ok, will do. Will post back soon. Thanks.

[nickBcap]

Re: ESR Meter Calibration, no manual

Testing the same capacitors on the multi meter gives equally erratic results. I will test the capacitors today in both devices. The multi meter tests some lower capacitors with low values with near accurate results, so may be I tested some caps that were not completely discharged on the multi meter also.
I will post back in a day or two, thanks.

[mmartell]

Re: ESR Meter Calibration, no manual

Test the resistors with your multimeter too.

[nickBcap]

Re: ESR Meter Calibration, no manual

...or I will post back in 5 or 6 days.... soon, thank you

[nickBcap]

Re: ESR Meter Calibration, no manual

Hi, thanks for you helps on this one.
I figured out both the ESR meter and the multi meter were not discharging before I was taking a subsequent reading. Well that is my inexperienced theory for now. This time around I began shorting the multi meter probes after each reading and watched as the reading backed down from something like 1500 to 0 in about 2 seconds and realized what it really meant to wait until the multi meter is fully discharged before taking another reading. So now I will turn off the multi meter for around 15 seconds to be sure the multi meter has discharged fully and then I may get correct readings.
Also I think one of the capacitors on the ESR board is dead because it is one of the three capacitors that I get a reading that immediately shoots up to around 1500 reading when I begin to measure it with the multi meter then drops to 1 then to 0.