The instructor in one of my classes at Vision said the proper way to test a relay was to remove it, apply power and ground to the control side and then check resistance through the load side. I don't think I like that idea.
That test isn't going to give you a result you can have great confidence in and it isn't going to be a quick and easy test to do. A relay or switch needs to be tested at near its' working current . Which is why there are a variety of by-pass tools and breakout tools for testing relay circuits.
I have relay tester I picked up in a Maplin clearance sale but it is also is of limited value -- it tests the relay is switching over repeated cycles but doesn't load the contacts to a representative load.
I keep a selection of known good relays in my tool drawer --- with relays swaptronics is sometimes the quickest easiest test.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Last edit: 7 years 6 months ago by Andy.MacFadyen.