testing capacitor with multimeter

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • chicagodiyer
    New Member
    • Dec 2012
    • 2
    • usa

    #1

    testing capacitor with multimeter

    Hi, I read that you can test whether or not a capacitor is working by using an ohm-meter. if its working the resistance will slowly increase if you connect the probe in the correct polarity and decreases if you connect it in reverse. Is this true?

    I tried doing this on a power supply board, almost all of the capacitor behaved as described above, except two capacitor, does this mean these two capacitor are not working anymore?( I did not desolder the capacitors and just test them on the unplugged board)

    I also did this test on a good capacitor and a slightly bulging capacitor (both were desoldered) and gave the same reading of slightly increasing resistance, does this mean the slightly bulging capacitor is still working?

    is this a reliable test to figure out which capacitor to replace? (i dont have an esr meter or capacitance meter.)
    thanks
  • Rulycat
    Badcaps Veteran
    • Apr 2010
    • 724
    • United Kingdom

    #2
    Re: testing capacitor with multimeter

    I made sometihng to check the capacitance a while back:
    https://www.badcaps.net/forum/showthread.php?t=19156

    See if this helps you in determining the status of these capacitors.

    By the way, if it bulges, it's bad!

    Comment

    • Dgtech
      E. Technician
      • Apr 2009
      • 1462
      • Steeler

      #3
      Re: testing capacitor with multimeter

      Depending on your multimeter, you might have a capacitance checker on it. A lot of fluke models have one. Whenever I remove a bulged capacitor, i check it just to see how it failed. Most of them fail lower in uF value than what it's rated for. For example, a good 1000uF measures 1033uF. I would change a 1000uF if it measures less than about 980.

      If you try your method with testing the lower cap, you wouldnt know it was bad. It would still charge up and discharge.
      The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS

      Comment

      • redwire
        Badcaps Legend
        • Dec 2010
        • 3900
        • Canada

        #4
        Re: testing capacitor with multimeter

        I find the multimeter test kinda useless for capacitors nowadays. You can check for shorts or high leakage, when an ohm reading levels and stays low.
        You don't know your meter's test current on ohms, so should it take 5 seconds or 15 or 30 seconds? Proof is your bulging caps look okay - at this point they should at least be low in capacitance due to electrolyte loss.
        I find it best to just "shotgun" whatever you are repairing - that is, change all the electrolytics. It's quicker than troubleshooting down to the exact part and there's no risk of leaving a weak part in.

        Comment

        • Tube_Dude
          Senior Member
          • Feb 2011
          • 51

          #5
          Re: testing capacitor with multimeter

          Originally posted by Dgtech
          . For example, a good 1000uF measures 1033uF. I would change a 1000uF if it measures less than about 980.
          980uF in a 1000 uF capacitor is 2% of tolerance!

          Usually electrolytic capacitors manufactures gave 10% or even more rated tolerance...

          Comment

          • Bills86e
            Member
            • Nov 2012
            • 24
            • usa

            #6
            Re: testing capacitor with multimeter

            Are there other parts on a cb that has electrolytics? It intrigues me that capacitors are
            a type of rechargable battery
            I'm a newby

            Comment

            Related Topics

            Collapse

            • dj8452000
              How To Test a P-channel Trench Mosfet Using A Multimeter In Diode Mode
              by dj8452000
              I am new to electronics and I'm understanding most of what I'm reading but I have a mosfet on my board that I've identified as a P-channel Trench Mosfet. I haven't a clue how to test this and what I should expect to see with the multimeter probes. I am hoping someone with years more experience than myself can help me understand how to use a multimeter to read this. Please look at the drawing I have attached to this and can you try to explain to me what I should be doing with my multimeter in diode mode and what results I should expect from a good mosfet?...
              02-18-2025, 08:28 AM
            • jinu_j
              How to test Subwoofer Amplifier with only a multimeter
              by jinu_j
              Hi Folks

              Need some advice on how to test a subwoofer amplifier if i have access to only a multimeter.

              Problem
              I have a Boston Acoustics active Subwoofer (soundware S). Its rated output is 200W. But the output i am getting is very low i can barely hear/feel it even if put the gain at max. I replaced all the capacitors in the Subwoofer amplifier but still no change.

              Is there anyway to test this without getting an oscilloscope/Function generator to see if the fault is with amplifier, driver or the source??

              Any advice would be appreciated...
              08-29-2024, 02:05 AM
            • chth96
              How Can I test PWM DM0365R?
              by chth96
              Hello
              I have power adaptor(220V/input, 12V 1.2A/output) which has symptom of fluctuating output DC voltage between 11.5V-12.2V.
              So I opened its plastic case and when switched it on, I heard constant tik tik sound from inside its PCB.
              I measured DC voltage between negative and positive pin of the largest capacitor(400v 10uf) and it was measured contant 300V.
              I also measured ESR value of all capacitors and I noticed that one of capacitor(KMG 16v 470uf), which located in the secondary side, have high ESR value(10 ohm),So I replaced it with same specification NXH capacitor....
              Yesterday, 04:14 PM
            • lmcancu
              LED Strip test points and testing?
              by lmcancu
              Hi is there a guide in this forum on how to test the LED backlight TV strips? I purchased an LED tester on amazon, but I am a bit confused on the test points and how to test the individual LEDs? I took apart a RCA 43" TV Rlded4331b. Please see attached pictures. I understand that all the LEDs are in series, but on these strips I don't see any individual test points for each LED? Any tips or guides?
              Thanks in advance...
              03-20-2023, 07:52 AM
            • ttmi100x
              HANNSG Hi221 -- 2 secs to black feat. CCFL flicker & "burn" marks on power board
              by ttmi100x
              Greetings everyone,


              I have a HANNSG Hi221 monitor that exhibits two seconds to black issues (backlight goes off, display is still on as confirmed by shining a flashlight on it) with some additional oddities...


              The monitor failed on me with a standard "2 seconds to black" some time ago prompting me to initially replace most of the electrolytic capacitors (some of them were bulging/leaking).
              Things kinda sorta worked for a night, then the problem returned along with some flickering and "buzzing" noises.

              Upon closer inspection...
              07-31-2024, 06:36 PM
            • Loading...
            • No more items.
            Working...