Hi all, I want to be able to test for an open circuit at the mains input of the opto. I have seen somewhere that over 5v the mains is disconnected. So I have used a 2.7v connection and then on connecting the other side you might expect a 2.7v drop over a connected 1000 ohm resistance.
Not getting this on an opto I am testing.
Do you guys think this is a valid test? Or is the another test to test if the opto is working?

 

If it fails, it will most likely fail short. Just do a continuity test across the output terminals. If it is open circuit, it is probably OK.

 

It may be open circuit in operation Ian. If it was shorted I would have been getting a voltage over the load. That is why I have suggested that test and need to know if is a valid test or not.
QUOTE="Ian0, post: 1837376, member: 719943"]
If it fails, it will most likely fail short. Just do a continuity test across the output terminals. If it is open circuit, it is probably OK.
[/QUOTE]

 

It may be open circuit in operation

I've used thousands of them, and never known one that failed open-circuit. All the failures were short, and generally accompanied a failed triac.