using ohm meter to test capacitors

Discussion in 'General Electronics Chat' started by electronis whiz, Jun 19, 2013.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
    519
    27
    I just pulled some electrolytic caps off a fried motherboard. I didn't see any of the usual signs of failed caps before I pulled them, but after pulling them I noticed that some the bottom was slightly pushed out and pushing the against the plastic wrapper that is folded over the bottom. most are like 1000 -4000 UF too high for my meter to test in cap range which maxes out at 200UF. I remembered I have don it before using ohm meter setting. usually put on one way then meter rises then maxes out reversal usually does same thing.
    last I did this was with my old DMM which max ohm was 2 meg ohm my new DMM goes up to 40 meg ohm. I try this test on the questionable caps it gets to about 2M ohm then it gradually starts heading back towards zero. does this mean those are bad or just result of using such high resistance range meter?
     
  2. tindel

    Active Member

    Sep 16, 2012
    568
    193
    If there is any bulging of caps then they need replaced. No need for an ohm meter - an ohm meter won't tell you if it's good or not anyway - it will tell you if it's taking a charge or not, but that tells you nothing about the ESR or capacitance.
     
  3. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    An ohmmeter won't tell if a capactor is good but may tell if it is bad.
     
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