Hi Michael,
Two things to help further your education:
1) there are almost always multiple devices in parallel, or
series with every device you may wish to test in circuit.
2) Sooner or later you have to test the courage of your convictions,
by removing the suspected bad part and testing it out of circuit.
That is the only sure way of not being fooled by the other parts
that share its nodes.
I find it more likely that you didn't notice that the optocouplers
are usually faced in opposite directions... some sending signals
to the high side, and others sending signals to the low side.
I still put an optocoupler failure in a switching supply at less than
1% probability.
-Chuck Harris
Mlynch001 wrote:
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Chuck,
Sorry, I was not at all clear, I should not have used the term "continuity" as I am using the Diode Test function on my DMM.
To be precise:
IC7 is open (infinity) in one direction (Red on Pin 2 and Black on Pin 1) and the meter reads 1.305 (volts) in the other direction (leads reversed from previous).
IC2 reads .512 (volts) in BOTH directions.
One thing that I have learned is that when two supposedly identical devices test so differently, using the same test instruments, there is a good chance that one of the two is defective.
I have also seen two posts on different web pages that have pointed to optocoupler failures on this particular power supply.
Does this alter your assessment of the situation?
I am always suspect of my knowledge and abilities, NOT questioning anything that you are trying to convey to me.
I appreciate your response and your patience.
Sincerely
