how to test optocoupler using multimeter?

Discussion in 'Technical Repair' started by zippora, Sep 14, 2016.

  1. zippora

    Thread Starter New Member

    Aug 27, 2016
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    0
    how to test transistor side of optocoupler using multimeter?
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,001
    3,229
    Generally, you can't unless the transistor has the base connection available externally.
    What is the optocoupler?
    Does your multimeter have a transistor test option?
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,524
    2,369
    If the base pin is there then it should check like a normal transistor on the Diode check scale.
    Max.
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Even if the base pin isn't there, you could try connecting the + and - probes of a DMM to the collector and emitter pins respectively, setting the DMM to an Ohms range, passing a small current through the opto LED and looking for a change in the meter reading.
     
    JoeJester likes this.
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
    744
    Put your meter on Diode test, across the C/E of the opto, power up the led and it should read or beep.
     
  6. zippora

    Thread Starter New Member

    Aug 27, 2016
    10
    0
    Thank you all.
    The optocoupler do not have the base pin. So I need to use second method you mentioned.
     
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