GRT Avionics

I have an HXr and the voltage has always read low.
I removed the display and made a new harness to test all 3 inputs with a battery.
The voltage read with a Fluke meter was 12.6 but the HXr showed 12.2 on all three inputs
This seem like a lot of error, Is this normal?
Thanks
-Rob

No.

Sounds normal to me.

The units have diodes (and probably other stuff) inside to make it possible for them to be feed from multiple power sources.

A .4 volt drop across a diode is not out of the ordinary.

Press on!

James

I disagree, mine reads correctly. It should be no worse tham 0.1 volts error.
Before calling GRT check all power AND ground connections.

A question of clarification ...

Bob,

Are you saying that you are seeing only .1 volt difference in the EFIS V1, V2,V3 and actual battery voltage????

I need to go back and check mine as I *think* that mine has always been a lot bigger difference.

Not disputing. Just checking to verify.

Thanks!

James

I have found the same thing with my HX system. The voltage measured by any of the EFIS inputs is always .3-.4V lower than what the EIS reads. The EIS happens to agree with what my DVM shows at the fuse block, so that's the one I pay attention to.

-John Basol

Curious. I have an Hx, EIS, and other brand D6. The Hx is on the avionics buss, the other two are not. All three agree within 0.1 volts if I turn off all other avionics. If I turn on the usual avionics I see that buss drop 0.1 or 0.2 volts. I figure it's a small resistance across the CB.

If you have a long harness and the HXr screen is at full brightness, you will see a voltage drop just because of the current through the wires. The backlight uses a lot of power. The voltage drop will decrease when you reduce the brightness of the screen.