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Hello All,

I purchased a UMA 3 1/8 inch electric tachometer specifically sold to work with the Rotax 914.

It arrived with no wires, just a dismantled 9 pin plug. 

It comes with what appears to be a peice of toilet paper sized instructions written in blurry writing so small that I need x5 ready-readers to make out what it says (I have a pilot medical so my eyes are normal). This two page "manual" is generic accross several guages, so they do not even provide specific instructions for the gauge they actually sold me. The instructions (attached PDF) say ....

"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*.

I posted this on the Europa forum and unfortunately the only answer was from someone with a 912 which is clearly different.

Has anyone actually wired up a UMA Rotax Tach to a 914 and can explain to me in English how to find the correct wires from the 914 to attach to the UMA tachometer and which of the 9 pins on the UMA plug to connect them to please - much appreciated.

Many Thanks 

Regards

Trevor

8576_1_10-04223instruct.pdf (You do not have access to download this file.)

Regards

Trevor

  • Re: Connecting UMA Tach Gauge to 914

    by » 4 weeks ago


    Hey Trevor. I connected that same Tach to my new 912.  Does the 914 engine come with a two wire harness with a factory connector like my 912 did? If so I can assist.


  • Re: Connecting UMA Tach Gauge to 914

    by » 4 weeks ago


    Hello Jim,

     

    The 914 does not come with a harness of this kind that I can find.

    It would seem that instead you have to somehow connect it to the Turbo Control Unit but it neither explains this in the UMA manual nor the Rotax manual.

    Regards

    Trevor

     


    Regards

    Trevor


  • Re: Connecting UMA Tach Gauge to 914

    by » 4 weeks ago


    Thanks All,

    I did finally work our the wiring for the 914 RPM gauge, no thanks to Rotax nor UMA - Bud kindly suggested to me that it is "all in the 914 manual" and yes he is correct, but there are instructions and "instructions written by an engineer for experts to follow" and I am an amateur builder. The words "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* Do not make easy reading to me. 

    I plan to write a set of instructions that are in plain English for UMA as the blurry, microscopically written set they provide is an insult to what appears to be a very nicely made instrument. It really should not take DAYS to work out how to connect an instrument. 

    Eventually I did this by ELIMINATION - the only wires left coming from the Turbo Control Unit (TCU) that were not connected had to be the tacho cables and when I put my x32 ready-readers on that I use to look at bacteria, I could see in super tiny pen writing on the cable the word "tach" done by the previous builder who I trust. Without this secondary reassurance, I would probably have removed the TCU and examined the plug or counted the pinouts to find wire 26 and 13 as they are not numbered or labelled by Rotax.

    Now the plug is wired, I find that UMA did not supply those little screws to screw the dismantled DB9 plug they supplied onto the tach they supplied. Way back 20 years ago I had boxes of these as "computer" plugs lying around spare with spare captive screws, which have all gone to landfill long since - I had to dismatle another device I was using that had some captive screws and steal them to secure the plug to the instrument - I hope this works when I get to engine start - ha - not impressed with UMA so far - how hard would it have been to supply a plug correctly wired that screwed into the instrument, I would happily have paid $100 extra for the many hours of time it took to work all this out. By comparison, my MGL engine instruments all came with wired plugs with COLOURED wires and a manual that at least mentions the colours and what each wire does. 

    Now I know why so many builders have a profressional do their wiring !

    Thanks again for support from the forum.

    Regards

    Trevor


    Regards

    Trevor


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