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Old 04-11-2019, 08:21 PM
bjdecker's Avatar
bjdecker bjdecker is offline
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 1,034
Default That wasn't it...

Tried the pull up approach, using the resistance calculated from the recommended incandescent bulb ( 12VDC, 0.1A [100mA] => 120 Ohm ) -- to no effect.

The Alternator is pulling the Lamp signal hard to ground. The alternator still produces power ( 14.2VDC @ 15A ) even though it shows failure.

Bought a replacement alternator; sent emails to Hartzell -- will see what the overhaul/repair reveals.

In the mean time, I changed all my G3X indications to a much higher limit for Volts (13.4 VDC)...
Brian Decker
RV-7 (Flying)
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Old 09-29-2019, 02:36 PM
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bjdecker bjdecker is offline
Join Date: Jun 2005
Location: Georgetown, TX
Posts: 1,034
Default Bad connection

Just to update this thread --

I removed the alternator put it with the "spare parts" and installed a brand new one, problem solved -- but not really.

A few weeks later, a buddy of mine was trouble-shooting his alternator and wanted to "borrow" the diode/regulator pack from my spare stock; I carefully removed the screws connecting and holding the diode/regulator pack in place and discovered that one of the 3 wires was broken and was just making a point-contact that was very susceptible to vibration...

So, key takeaways --
1. The ALT Light is probably a good thing to have wired into the G3X touch CAS.
2. It doesn't need a pull up resistor to make it work.
3. If it goes off (#assert) it means something is wrong - for real.
Brian Decker
RV-7 (Flying)
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Old 07-13-2020, 07:05 PM
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N130WN N130WN is offline
Join Date: Jan 2005
Location: 8A7 (NC)
Posts: 340
Thumbs up Success

I recently set this up as a discrete input on the GAD 27, no resistor or relay, and it works as hoped.

On the G3X, I configured GAD 27 discrete 1, active low, input state: active. This shows an alert when the G3X is first powered on, before engine start. The alert goes away after start, when the alternator is online.

Larry Bowen
RV-8 Built, sold, missed.
RV-7 Built, sold, missed.
RV-8 Emp in progress ...
RV-8A Purchased, flying.

Last edited by N130WN : 01-03-2021 at 12:40 PM. Reason: Added detail
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