Trevor,
On the back of the gauge you have 3 connection points and from the rear of
the engine you have 2 wires from the tachometer output coils.
Connect one of these wires to a good earth point and the second wire to the
Signal input on the gauge.
The other two connections on the gauge are for positive supply and earth.
Now I will also add that instead of taking the wire from the engine to
earth, I take it straight to the earth connection on the gauge which is
also separately earthed. The reason I do this is that I have done several
of these and on one installation I ended up with erratic readings and the
fix turned out to be reversing the two wire connections from the back of he
engine.
Have fun.
Dave Watts
G-BXDY Classic Mono 912S/Airmaster 2,700 hrs.
On Sat, 10 Apr 2021 at 2:25 pm, trevord <trevord@orcon.net.nz> wrote:
>
> Hello all,
>
> Perhaps someone has covered this already - I would be happy to be directed
> to the answer if so.
>
> I am trying to do something that would appear quite simple, connect the
> UMA tachometer specifically sold for the Rotax 914, to this engine.
>
> The UMA "Manual" is toilet paper at best with the cryptic note "Connect
> the signal wire of the tachometer to one of the wires from the output
> coil/pickup, and connect the other wire from the output coil/pickup to the
> same ground point used by the tachometer.
>
> The Rotax install manual appears to be translated from Latin and states (I
> am not making this up) "Feeding wiring to electric rev counter from the 36
> pole receptacle of TCU - connections: flexible wire 0,75mm2 (18AWG) white
> No.26* and flexible wire 0,75mm2 (18AWG) white No.13*.
>
> Now, I used to do electronics as a teenager, so this should be easy, but
> it seems both manufacturers have written instructions to keep avionics
> technicians in a job - this is cryptic at best.
>
> The UMA tach did not even come with any wires, just a dismantled plug and
> the Rotax 914 TCU has umpteen white only wires coming out of it...
>
> Has anyone actually managed to do this without expert help and can explain
> to me in plain english.
>
> Thank you so much
> Regards
> Trevor
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=501334#501334
>
>
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