Lots of broken capacitors

Discussion in 'General Electronics Chat' started by Addison, Sep 21, 2014.

  1. Addison

    Thread Starter New Member

    Sep 21, 2014
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    Hello, about two weeks ago I bought a box o' capacitors from electronic goldmine because I read some good reviews and I wouldn't mind having some extra capacitors lying around. I currently play around with electronics at home; making circuits, tearing things apart, etc. My issue is that when I started to sort out this box of capacitors, I found that a lot of them were broken to my knowledge. Every time I hook my capacitor up to a particular capacitor, there would be no reading. The funny thing is that it seems to be certain types of capacitors that aren't being read and then there is other types that are working fine.

    To get to the point, my question for you guys is should every type of capacitor be able to be read with a multimeter? I suspect there might be certain types that can't be detected by a multimeter. Below are some of the capacitors that did not read a value?

    A side question: I received 10 paper-in-oil capacitors that say 0.068(uF presumably), but they read like 0.080uF. Is that kind of tolerance expected? (Yellow thing in picture)

    Side Question #2: There was 3-4 different types of ceramic disc capacitors. They said things on them like R2R1, R4R7, R3R9. There was nothing that showed the capacitance, just numbers like this: R2R1, R4R7, R3R9. The weird thing is when I plug them into my multimeter, which has a 4000uF max, it shows OL. Something seems fishy, so is this normal or is this an indication of the capacitors being bad?

    Thanks for your time.
     
  2. studiot

    AAC Fanatic!

    Nov 9, 2007
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    How do you know the capacitance ranges on your meter are working properly?

    Do you know the test voltage applied by the meter, is it suitable for all the caps?

    The leads of many componenets oxidise with time and you can get a bad connection with crock clips to old wires.

    Yes a .068 old type cap could easily read .08

    Oh and please don't use such large files fopr the pics when it is not warranted 0.25M would have been enough.
     
  3. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Not necessarily. You might want to turn off the auto scaling on your meter to keep it in the high resistance position. If you're actually using the capacitance function, you may have more capacitance than they meter can read.

    I would ALMOSt bet that all those caps are good. :)
     
  4. ISB123

    Well-Known Member

    May 21, 2014
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    Charge the capacitor using battery and connect resistor and LED in the circuit if LED is still emitting light for a while after battery was disconnected then the cap is working.
     
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  5. alfacliff

    Well-Known Member

    Dec 13, 2013
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    the r is a decimal point.
     
  6. Addison

    Thread Starter New Member

    Sep 21, 2014
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    I apologize about the big files, they were that size when they came off of my camera phone, and I know that some forums automatically resize when they are uploaded. I shall resize them next time.

    I tested my multimeter with electrolytic capacitors that I have had and it was reading them fine.

    My multimeter does not have an auto ranging option, so I don't think that is the issue. I have been setting it to 4uF and the capacitors I try still do not read anything.

    So if the R is a decimal point, what would be the capacitance for the three that I listed above? R3R9, does that mean 0.3.9 3.9, or 0.39?

    As for the battery trick, the capacitance values are too low to even see a LED turn on for a second. I tried it with a broken capacitor and nothing. Then I tried it with an electrolytic and it worked. Then I tried it with a working ceramic disc capacitor and it did not work. By did not work, this means I could not see a flash of light. Even with the electrolytic it was small.
     
  7. ISB123

    Well-Known Member

    May 21, 2014
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  8. Brevor

    Active Member

    Apr 9, 2011
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    That wont work for the small value capacitors that he has.
     
  9. Addison

    Thread Starter New Member

    Sep 21, 2014
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  10. vk6zgo

    Active Member

    Jul 21, 2012
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    Are you quite sure they are capacitors?

    From time to time I have run across resistor which are in a very similar package to small mica capacitors.
    We verified that they were resistors by tracing the circuit,reading the labelling on the PCB,measurement,& substitution.

    If some of these became mixed up with caps,they would not test OK as capacitors.
     
  11. Addison

    Thread Starter New Member

    Sep 21, 2014
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    I just checked the resistance on them and they all show OL on the screen, so they are not resistors.
     
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