Grand Rapids Technologies EIS Instrument Failure

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Methusala

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Joined
Sep 19, 2020
Messages
7
I have the above unit, 10 yrs old on a Rotax 582. It has been faultless till a few days ago when I noticed that the tachometer was displaying obviously erroneous info. Soon after that it appeared to freeze, still with the display working but the info was not updating. Has anyone experienced similar problems and what may be done? Any information or suggested remedies welcomed. Thanks Don
 

Daleandee

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Sep 11, 2015
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Is it just the tach reading or is it all of the readouts? What happens when you go to another page?

Been a few years ago but I had one in a VW powered Sonex and it was an excellent piece of equipment. No issues with it at all.
 

rv7charlie

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Nov 17, 2014
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1,367
Location
Jackson
What troubleshooting have you done? From someone with at least three past lives in electronics maintenance: When the problem isn't obvious, do the easy stuff first.
1. Reboot (I'd assume you've done that by checking that it's still acting up after shutting down and restarting)

2. Wiring/terminations

3. Sensor (if it counts pulses, try making/breaking the tach line rapidly to see if the display reacts)

4. Substitute a sensor & wiring, if one is available from a friend who's running the same setup

5. Call GRT for additional troubleshooting hints, before returning it for service.

Charlie
 

Methusala

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Joined
Sep 19, 2020
Messages
7
Thank you for your suggestions. I will check the unit in the next few days and , if necessary, seek GRT help in repairing it. Don
 

Dan Thomas

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Joined
Sep 17, 2008
Messages
5,745
From the EIS R-1 tach installation manual:

1614980082664.png

Those isolators are just resistors. I don't remember the resistance. I installed an EIS engine monitor or two in airplanes, and in one I had to use those isolators. Too much signal voltage confuses the brains in the instrument and it will act up, though I never saw one seize up entirely.

https://www.iflyei.com/wp-content/uploads/R-1-OI-II.pdf
 

Methusala

Member
Joined
Sep 19, 2020
Messages
7
Thanks again for your interest and suggestions. This instrument has been installed in my plane for over 10 yrs. During this time it has operated without a glitch. It has only just become erratic, so I don't think it is an installation problem. It is possibly age related, however I will check the security of the plug connection and for possible wiring breaks. One hopes whenever this type of bug occurs that someone has experienced it as well and found a simple solution. With my luck it is probably the 2nd law of thermodynamics (over time order descends to chaos).
 
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