rev counter

[norsa]

Guys. The rev counter on the midget suddenly packed up. A new/replacement may not be available. Ive done some testing, but could use some available wisdom.
With engine running, i have a good ground to the unit (negative) I have a good 12v feed to it, back light works, have continuity coil - to rev counter. I dont have multimeter with rev counter. Thoughts
Nick.

 

[The_Yellow_Ardvark]

12v supply is normally for the back light and earth.
Then a 3rd wire gives the signal and that returns through the earth. This feed is from coil or the charging circuit.
What system do you have?

 

[norsa]

system? 4 wires to the back. ground... live (light circuit..... live from somewhere and continuity wire from coil -

 

[500e]

There was another counter that had wire from coil+ through a small loop of wire on back of rev counter then back to coil + one length of wire no break

 

[500e]

We ran these in the 1300cc class of the national rally championship for years

 

[500e]

We ran numerous cars for other people

 

[evobilly666]

Are you measuring the supply with a multimeter? Is it digital and is it set to dc? Iirc alternator (clue) outputs are ac and a digital mm may not show fluctuations. Probably well off the mark but worth considering.

 

[the snooper]

Are you measuring the supply with a multimeter? Is it digital and is it set to dc? Iirc alternator (clue) outputs are ac and a digital mm may not show fluctuations. Probably well off the mark but worth considering.

i think the rev counter gets it pulse from the ignition coil not the alternator on this car

 

[normspanners]

you havnt swapped the wiring on the coil, inadvertently there is usually two similar connectors, the tacho wire needs to be on the negative one. if it is on the positive it wont get the pulses.

 

[norsa]

no it stopped whilst I was driving it. maybe ill get a mm with rev and dwell. that would be handy as its got points and stuff.

 

[norsa]

i think the rev counter gets it pulse from the ignition coil not the alternator on this car

correct. negative side as normal in this age.

 

[the snooper]

I had an Essex v6 with points I added an electronic module to the ignition, it still used the points to switch but a lot less power going through the points, the module had a 3 way switch conventional off and electronic and switching between conventional and electronic made a huge difference more power was delivered to the coil so if you get change of one they are worth having plus the points don't burn out or become pitted