Hi, Got one of the repo tachs for my 71 GS convertible clone but not sure on the wiring. It has a white back and has 2 connections - I assume one for ground and one for the coil. Connections are same as on the clock - one is horizontal and one is vertical. Anyone know which one is ground and which one is the coil? Thx, Ian jigordon@sympatico.ca 71 GS Stage 1 convertible (clone)
The originals only have one connection for the coil. If they aren't marked, put an ohmeter from each connector to the case. One connection will read a resistance, the other will be the ground.
Sorry -more info. checked the crazy thing again - it has 3 connections. One is ground, I presume the other 2 are: coil minus +12V just like a modern tach (These repos look like they have the guts of a modern tach(. From the back, three connections: Right = Ground Middle = ? Left = ? Anyone? Thx, Ian jigordon@sympatico.ca
Ian, That's a new one. Where did you get this Tach from? I'd be interested in seeing a picture if you have a digital camera. I have an Autometer Tach in my dash because the stock one gave out, and I have never heard anything good about the repros. The Autometer uses 4 connections(+12V, Grnd,Coil-, and lighting) But if someone is putting modern tach guts in a repro 70-72 GS tach, I for one want to know as much about this as I can. Any info you can provide would be great.
Got it from ebay a couple of years ago. It has 4 connections - I didn't include the lighting. I'm sure it is a repop - plastic case, and I had it apart to trace out the circuit schematic - getting a little rusty but it gave me some clues. Ground is easy (uses same ground for lights as for tach, but which one is power and which one is coil - is unknown. Any help appreciated. Thx, Ian jigordon@sympatico.ca
Ian, I would say there is no way to tell. I would go ahead and attach it to 12 volts, and the coil. It will either work or not. I don't thinkyou will hurt anything if you hook it up wrong. You have 50% chance of getting it right. Murphy's law says you hook it up wrong the first time, LOL
Took your advice - and in fact it worked with JUST the coil - connection to the middle terminal on the back - not quite sure what the other connection is for - when I did hook it up to +12 it stopped working, and reversing the connections didn't make it work either - seems accurate up to about 2000 rpm (will test in car when running to make sure) but seems OK so far.... Thanks for the advice. Ian jigordon@sympatico.ca
