OK so I was looking at a friends machine (roadshow) that had a solenoid that was not working. I pulled out the mutlimeter to see if it was getting power to both lugs or not. First was fine, when I tried the second I got a spark and the solenoid activated. Now it is operating normally. I don't get it... Any explanations would be very welcome!
That was about what I worked out! I reckon something else is going on and that it is going to stop working again though and worry about the long term survival of the patient without a transplant of some sort...
My only guess is that multimeters do use a very little bit of voltage to make the test. The voltage that fires a coil is actually pretty low (I think ~1.5v). I guess there's a small possibility that testing on the side that the transistor fires to when grounded, somewhere along the lines in the test, there may have spiked enough voltage from the DMM to fire the coil. This is just a theory, but that would be my guess...
I suspect that is what happened to fire it. What I really don't get is why it was not working at all but then after the DMM fired it it is working again. I am guessing it will stop again and I can try and diagnose better then.
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Tilton, NH