Quote:
the sprint rev counters do work off the coil.
I made up a test loom for my spare rev counters so that I could connect them to the coil in the engine bay.
sometimes you have to tap the glass to wake them up, seems to be a common problem.
My 1850 has a luminition unit fitted and the rev counter/tacho works fine with that, other electronic ignition units may be different.
Not sure how you would test a tacho with a signal generator, maybe google can assist.
Malcolm
My theory is a rev counter works by reading the pulse from the points switching on and off. In theory this pulse will look like a waveform on an oscilloscope.
So in theory you could use a signal generator to send the same function to the rev counter and get it working. I am not sure what function would be correct. I suspect a square wave, as the point are suppose to switch off pretty rapidly.
Anyway the loom is homemade, so the first thing I will do is check the wiring.