More tach questions

[Jeff Erwin]

I have this tach:

The internals all look great:

No burn marks, no charring, no smells. Only thing I notice is that the needle on the face, when I move it manually, does not return to 0 by itself, I have to move it back. Don't know if that is correct.

In any case, I hook up the negative side of the coil to the correct post, power to the correct post and ground one of the other lugs. Double check all connections.

Start the engine, nothing. Needle doesn't move. I am getting 12v to the instrument and double checked the negative side of the coil.

So is this thing just toast? Can it be fixed? Am I doing it wrong?

 

[Rockland71GTX]

I can't help with that, but RT engineering has a solid state board to replace the electronics:
https://www.rt-eng.com/index.php/67-74_Tach_Board_with_Calibrator_Built_In.html

 

[pnora]

What ignition are you running?

 

[Billccm]

I 2nd the rt-eng.com solution. I have some tach troubleshooting videos I can send to you.

 

[Jeff Erwin]

Problem found and solved. The clue was the needle not returning to 0 if I moved it manually. In looking over the information on the replacement circuit board they mentioned the needle and a small adjustment screw that affected its movement. I had to take the thing mostly apart but found the screw. The needle was too tight.

Hooked it all up to power, ground and negative coil and it works perfectly!

Thanks to everyone for your help!

 

[davek]

thank you for letting us know.