Tach Transducer

[mslev100]

I just finished my RV-7A and am having problems with the tach reading. I have an O-360 with Lasar ignition and Dynon Engine monitor D120. The tach reading is extremely erractic - varying hundreds of rpm's in seconds. I have checked the engine with a remote tach which reads steady without the significant variations displayed on the Dynon engine monitor. I am using the tach transducer I bought from Van's and I have confirmed the wiring is black to ground, red to 1> amp fuse and white to the monitor wire. I talked to Van's and they now say that they don't think the transducer is compatible with the Dynon monitor. I would appreciate any suggestions.

 

[dynonsupport]

Plenty of people have used the transducer with great results, so we know it works. Is it one of the "VTACHGEN" parts?

You should not have a resistor between the transducer and the EMS. Just checking that this is true.

If there's any noise on the power for the transducer, this could cause weird readings. Are you running it off the 12V out from the EMS or the aircraft power?

The only other thing I can think of to try is the other EMS RPM input. It will use whichever input has an RPM input, so this might tell you something.

 

[mslev100]

It is one of the "VTACHGEN" parts. There is no resitor between teh EMS and transducer. I have the transducer hooked up to the airplane power through a 1 amp fuse. I have the EMS on a separate 5 amp fuse. I'll try switching ot the other PRM output.
Thanks.

 

[paul_romine]

So,
Did you get it to work? I am just hooking up my transducer and wondered if I was goin to have a problem too.
PR

 

[mslev100]

I did get it to work and confirmed it against a remote prop tach. I switched the p-lead wires and for reasons that escape me, it seemed to cure the problem.