[RedBarchetta]

Paul, it's a SPF factory Smiths tach. Worked fine until I disconnected my ignition system (MSD 6AL, etc.) for maintenance. When I buttoned-up the ignition, the tach started to bounce and then it went dead. The tach is wired with one, 5-wire connector plug. I guess it's possible for a bad ground, but the circuit (according to the SPF owners manual) is also shared with other instruments and components. So I don't suspect a ground problem, as all other components are functioning. I have also researched this problem and apparently it's hit or miss with Smiths tachs and MSD ignitions. The tach has a weak circuit board and is prone to failure from voltage spikes.

The new circuit board that I'm having installed will allow me to bypass the MSD box altogether and go straight to the (-) side of the coil (as was factory installed).

-Deano