Tach Gauge repair

[zimme008]

I have a set of Airguide gauges on my recently acquired 76 Crestliner Apollo/850 Mercury and the tachometer no longer works. The wiring is good and I've tested for current and no problems there. Anyone have any suggestions for how to repair the tach? I'd like to keep it original if possible.

Thanks

zimme008

 

[Silvertip]

Re: Tach Gauge repair

The tach is probably not repairable as the bezel would very likely be damaged in the disassembly process. There are typically four connections on a tach. 1) instrument back-light (should measure 12V with light switch in the ON position). 2) Ground - should mesure zero ohms to ground (battery negative). 3) +12V - should measure +12V with ignition switch in the RUN position. 4) I -- this is the ignition terminal and the voltage measured here would be an AC signal from the stator. Measuring 3-4V would indicate the tach signal is ok and the tach is indeed dead if all other checks are normal.