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No RPM Readout after trike rebuild

in 912 / 914 Technical Questions 11 years ago

  • Re: No RPM Readout after trike rebuild

    by » 11 years ago

    Bill,

    Just checked the resistance across the trigger coil - I'm getting 232ohms so this looks ok.
    When the engine is running what would I measure to ensure that the trigger is picking up the rotor - is it a voltage that is produced??

    Many thanks for the help!!


    Steve.
      
    Report

  • Re: No RPM Readout after trike rebuild

    by » 11 years ago

    Steve,

    The trigger does produce a voltage spike once per revolution but it happens so fast (1000rpm and up) that that you wouldn't be able to read it with a voltmeter. If you have access to an oscilloscope, you can read it that way. There is an illustration of the waveform of a properly operating trigger in the heavy maintenance manual. (click on manuals under the support tab at the top of the page)

    I've never actually checked a trigger with an oscilloscope. Every trigger I've ever checked, I've done with the volt/ohmmeter.If you are getting the proper ohm readings, and apparently you are, I'd say the trigger is OK and the problem has to be the gauge. Unless the trigger has been moved, I doubt seriously it is out of adjustment. Maybe Rob or Roger could jump in here and lend their expertise.

    Bill.
      
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  • Re: No RPM Readout after trike rebuild

    by » 11 years ago

    Yes, it's very strange! Didn't think a gauge would just stop working altogther.
    The trigger wasn't moved so I can definately rule that out.
      
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  • Re: No RPM Readout after trike rebuild

    by » 11 years ago

    I got my rev counter fixed today!! After having absolutely no luck in sourcing a quick swap replacement I decided to open my existing gauge and find out what was wrong. The solder joint on the negative wire had a dry joint - Luckily I have a very good soldering iron so I reflowed the joint (it seemed to use high temp solder) and then checked for continuity to the pin on the rear of the gauge and all was good.
    Inserted it back into the aircraft and she's working a treat!
    PS - Opening the gauge is a complete bitch!

    Many thanks for all the replies!! Panic now over!!

    Steve.
      
    Report
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