C / ESR meter and capacitor leakage current tester.

Thread Starter

bob2

Joined Jun 15, 2019
200
This analog multimeter has a capacitance measurement mode of capacitors up to 2000 μF. By changing the polarity of the probes, we estimate the leakage of the capacitor.
In addition, there is enough space inside to accommodate the ESR meter board.
ESR is measured at a limit of 50 uA.
Power supply voltage is 3V.
The only refinement is a micro switch that connects the ESR meter in 50uA mode.
The input terminals of the multimeter has a fuse.
The countdown is on the Ohm scale.
The ESR meter scale is almost linear.
 

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Thread Starter

bob2

Joined Jun 15, 2019
200
Hi
In more detail about work of a multifunctional multimeter.
Capacitor capacitance measurement.
On the red scale, you can estimate the capacitance of the capacitor up to 2000 μF, if the capacitance is larger, the arrow goes to the end of the scale.
In many cases, it is possible to measure the capacitance of the capacitors in the circuit. But it must be taken into account that the voltage at the output is 3V, therefore, the influence of other components is possible.
Everyone knows well that it is necessary to discharge capacitors before measuring. But there are different cases in practice and the meters fail because of this.
The multimeter has a safety fuse. But you need to work without fanaticism, adhering to certain rules.
A leak.
Capacitor leakage estimation is an old method that has been used by those who work in the field of repairs for decades. The method still remains relevant.
The only drawback is in 1k mode, voltage 3v.
But switching to 10k, we get 12v. This is a big plus of this multimeter.
ESR meter.
Scale 0.002-5ohm.
The operating mode of the circuit was very carefully debugged. Therefore, the scale is almost linear. There is little non-linearity only at the end of the scale.
The maximum sensitivity of the circuit was achieved by using a specific transformer that can operate on 3V and the very sensitive mode of the multimeter 50μA.
Probes in the form of tweezers 40 cm long. The use of a thick, flexible wire, introduces a minimum error in the measurement.
Thus, we have a multimeter capable of assessing the operational state of a capacitor by three main parameters — capacitance, ESR, leakage.
 
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DickCappels

Joined Aug 21, 2008
6,591
I have never felt that I needed one either, but I have a friend who is constantly refurbishing old electronic appliances and I doubt he could get much work done without an ESR meter or just shotgunning it and replacing all the old electrolytic capacitors.
 

Thread Starter

bob2

Joined Jun 15, 2019
200
I have never felt that I needed one either, but I have a friend who is constantly refurbishing old electronic appliances and I doubt he could get much work done without an ESR meter or just shotgunning it and replacing all the old electrolytic capacitors.
Yes, such devices are most needed by those who service and repair various electronic equipment.
Regarding the technical capabilities of the ESR meter.
A good ESR meter should not only determine whether the capacitor is good / bad, but also measure this parameter with maximum accuracy.
 

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Thread Starter

bob2

Joined Jun 15, 2019
200
Hi,
In-circuit measurement of capacitance in different situations.
Naturally, it raises a lot of questions.
Measuring signal of a multimeter in the mode of measuring capacitance. Influence of other components.
Two multimeters measure differently, but the result is almost the same.
We see that in this case, there is no influence of other components. Two multimeters correctly measure the capacitance of the capacitor.
 

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rsjsouza

Joined Apr 21, 2014
262
I usually repair old electronics and have done numerous tests to evaluate leakage in old capacitors.

Sometimes the degradation is quite obvious - most commonly is the reduced capacitance due to dielectric loss (common in aluminium electrolytics) but the effects vary greatly with solid dielectric ones. Yet yesterday I got a "X2" solid dielectric capacitor that is severely reduced in capacitance, probably because in its lifetime it was hit multiple times by transients.

One aspect of leakage is that, depending on the maximum voltage of the capacitor, the leakage will vary greatly. In my experience, when repairing switching power supplies or vacuum tube circuits, the large high voltage capacitors can show low leakage under the very small voltages of a DMM or a LCR tester, but orders of magnitude higher leakage under the stress of hundreds of volts. For that you could count on one of the vintage vacuum tube leakage testers or make your own.

A similar thing happens for semiconductors such as diodes and transistors, especially when they operate under stress: when trying to evaluate their performance, sometimes submitting them to a low current/voltage swing of a diode tester is not enough to trigger a bad behaviour.
 

Thread Starter

bob2

Joined Jun 15, 2019
200
Hi,
The multimeter has pretty high-quality measuring probes.
You can even measure low resistance resistors up to 0.1Ω.
 
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