user9253
Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan
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 Posted: Mon Aug 18, 2014 6:51 pm Post subject: Dynon D-180 & flickering LEDs |
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I have been corresponding with a RV-12 owner in TX. His Dynon D-180 has a problem with LEDs that flicker when they should be on steady. The D-180 supplies negative PWM voltage to LEDs which are external to the D-180. Download the D-180 Installation Manual http://www.dynonavionics.com/downloads/Install_Guides/FlightDEK-D180_Installation_Guide_Rev_H.pdf
and read about "External EMS Warning Light" on page 4-10. The aircraft owner did some experiments. Here are the results:
With the engine off and the D-180 powered by the aircraft battery, the LEDs are on steady. With the engine running, the LEDs flicker. With the engine still running, if the avionics switch is shut off, the D-180 reverts to its internal backup battery and the LEDs illuminate steadily. Engine still running and the avionics switch is turned back on, the LEDs flicker again. This experiment was repeated and the results are consistent. From these experiments I conclude that the D-180 puts out a steady PWM voltage when operating on battery power (whether aircraft battery or internal backup battery). And when operating off the alternator, the D-180 puts out an intermittent PWM voltage which causes LED flicker.
With the engine running, the D-180 indicates a system voltage of 13.7 which is normal for RV-12s. All E-LSA RV-12s have a 22,000 microfarad capacitor connected to the output of the Rotax rectifier/regualtor. If that capacitor is bad, could that cause the D-180 to output an unsteady PWM voltage to the the LEDs? Or should the D-180 be able to function even if the aircraft electrical power is dirty and not pure DC?
Thanks, Joe
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Joe Gores |
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