MoreDat

A Student Network for Collaboration and Sharing

Signup on MoreDat.com

What’s Next For Electronic Devices. Have you heard of FPGAs? Find out now here. And as a bonus get your free guide to writing a successful resume. Just Signup now and it’s all yours free.

Would the process below be any different testing capacitors in circuit on board.

1) Discharge the capacitor by shortening its leads. That is - use a wire and connect the leads of the capacitor together. This will discharge it.

2) Put your multimeter in the high ranges 10K-1M

3)CONNECT MULTIMETER TO CAPACITOR LEADS(OBSERVE THE POLARITY IF ELECTROLYTIC). AS SOON AS THE LEADS MAKE CONTACT, THE METER WILL SWING NEAR ZERO. IT WILL THEN MOVE SLOWLY TOWARD INFINITY. FINALLY THE METER WOULD COME TO BE INFINITE OHMS BECAUSE THE CAPACITOR IS BEING CHARGED BY THE BATTERY OF THE MULTIMETER.

4) IF THE CAPACITOR IS BAD, IT WILL GO TO ZERO OHMS AND REMAIN THERE. THIS IS CALLED A SHORTED CAPACITOR.

5) IN THE CASE OF AN OPEN CAPACITOR THERE WILL BE NO OHMMETER INDICATION.

6)SOME CAPACITORS HAVE A LOW DIELECTRIC LEAKAGE. YOU WILL KNOW THIS IF THE OHMMETER COMES TO REST AT A POINT LOWER THAN INFINITE. TEST A KNOWN GOOD CAPACITOR OF THE SAME TYPE TO BE SURE

1000uf 16v capacitor test results after discharge on x10 scale analog meter

measurement upon reading goes to about 5 ohms and stops
when reversing leads, goes to about 60 ohms and stops on some and discharges on others
my analog meter is powered by 2 aa battery, 3V is that enough voltage to
load capacitor? or is still being in a circuit giving me strange readings?
I am getting readings like this on Caps that appear fine.
Thanks for your help.

Views: 46

Reply to This

Replies to This Discussion

The process you describe is essentially correct for simple testing of capacitors out of the circuit.  However there are two things I would change.

  1. When testing an electrolytic capacitor you do not need to observe polarity.  You will be reversing the leads anyway, so polarity is of no concern.
  2. The scale you set the analog meter on will be determined by the value of the capacitor.  Use higher scales for smaller capacitors, use lower scales for larger capacitors.  The voltage and internal resistance of your analog meter also affect your results, which may require different meter settings.

As far as testing a capacitor in a circuit, there is no good way to do it using a meter because it will be measuring all of the rest of the circuit that the capacitor is connected to.  If you suspect a capacitor is at fault, the best in circuit test would be to bridge a capacitor of like or similar value across it in the circuit and use an oscilloscope  to see the results.  In the case of audio circuits you just need to listen for a change in the output.

RSS

© 2024   Created by Jerome Trent.   Powered by

Report an Issue  |  Terms of Service