Dave Dobeson wrote:
Andrew9
It should not be the back emf from the starter motor causing your problem. If it was it, would also probably fry any other lights, radio etc turned on.
A positive earth generator would fry it as would a high current (maybe short circuit) in fuel gauge and sender or engine temp gauge and sender circuits.
Do you have the filtering capacitors either side of the 7810?
That's what he said it was, the EMF, or magnetic field of the motor collapsing as it is turned off. I don't really understand that stuff myself.
Car is now negative earth with an alternator, was positive earth generator a long time ago.
I haven't got around to using a multimeter to check anything, both the fuel gauge and temp gauge "work" they are just a-ways of; Temp gauge is half way when car is cold, and hot/overheating when at normal running temp. Fuel gauge shows empty when empty, but full when only half full. so they seem to behave how I would expect with the slightly higher voltage.
I didn't use any caps, as I thought they were only to provide noise suppression? as opposed to providing protection to the chip, but it might have helped?
I plan to measure some stuff to check no weird voltages or anything and then probably fit a Old style metal voltage stabilizer.
I have a temporary digital temperature gauge fitted, so I've not worried about fixing it for a while