[TechAssist] Opto-Isolator testing
- From: "Christopher Barnak" <cbarnak@xxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Tue, 26 Jul 2005 12:30:57 -0400
Yes Ken, I have tested many an Opto-Isolator by
applying voltage to the secondary pens of the opto
on the secondary side of SMPS. Either current limit
your power supply or use a current limiting resistor
or use the resistor that already may be there. I have
had good luck without having to remove any componets.
Connect your meter to the primary side of the opto and
put it on diode or ohms. Start with 0v on the sec. side
and gradually increase it (observe polarity). At some
point the primary will go down to almost a dead short
in ohms reading. The OPTO should be good if it does.
The fixture thing sounds good, if the opto can easily
be removed.
But like you, lately I have been replacing it. I'm afraid
of the possibility that the opto was damaged due to
a overvoltage condition and may be intermittent or
not work properly under operating voltages. I was
bit by ONE of those boggers.
Chris Barnak
Norfolk Public Schools
Norfolk, Va.
-=-------------------------------------------------------------------------------------------------
Jerry,
That is a truly outstanding suggestion. I have often wondered how I
could check an opto-isolator, but usually just replaced them if I had
any
doubts. Bet I've replaced lots needlessly.
May try to build a test jig with a socket, battery, limiting resistor,
and posts for a meter.
You have helped many techs with that suggestion.
Thank you,
Ken Smith
Gulf Technical Services
3034 Gulf Breeze Parkway
Gulf Breeze, FL 32563
850-934-8324 (Voice) 850-932-0819 (Fax)
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