Maidna@comcast.net
I love flying!
- Joined
- Jun 16, 2018
- Messages
- 5
I would like to verify whether the following conditions could possibly harm a Skyview Classic EMS-200 unit and/or devices attached thereto:
1. Leaving an unused, unconfigured input pin, specifically C37-P22, physically shorted to ground.
2. Powering up a Dynon C-to-V converter (Dynon p/n 100654-000) when its output signal (white wire) is shorted to ground, remaining powered up for 15 minutes to 2 hours at a time.
I can't think up any reason for number 1 to be an issue for any EMS input. But, trying to be a hair smarter than the average idiot, I try to remember I don't know what I don't know, and ask for expert opinion.
For number 2, the converter was either disconnected from the fuel tank's capacitive plates, or connected to the tank of a Van's RV-9A, with varying amounts of fuel in it from empty to full. The C-to-V converters' outputs on my RV-9A range from ~0.9 to 1.3 V, empty to full, as read by the EMS-200's enhanced general purpose input pins. When the converters are disconnected, the output voltages are ~0.2 V.
Background details:
I recently had to rewire the C-to-V converters in my airplane after de-winging it for over-the-road transport following an off-field landing. (Long story...)
When everything was back together, I discovered the left tank converter output wire was shorted to ground. No amount of fuel in the tank changed the reading from 0.000 V. Rather than take everything apart (AGAIN!) to track down the short, I fixed it by configuring a blessedly accessible, unused enhanced GP pin, C37-P31, for the left tank level. Cutting the converter's white wire, I connected it physically to C37-P31. That left the other side connected both to ground and to pin C37-P22, now de-configured and unused.
Although both tank levels now respond to varying fuel levels as they've always done before (the right C-to-V converter was rewired correctly and worked from the get go), I would like to confirm whether some latent harm may have been done to the left C-to-V board. It should have been trying to raise its output to 0.2-1.3 V, but the current it could put out went directly to ground. Since no fuses blew, and input voltage didn't sag, I surmise the output current must be limited. What is the max output current?
It's of interest because the re-routed wire connecting P31 and the C-to-V output now goes through the fuselage next to the fuel line from left wing. Bad juju, I know, running wires next to liquids in tubing. I wrapped the fuel line with extra anti-chafe insulation, and the co-linear run about 3" at most. The probability of the C-to-V board or the EMS P31 pin pumping enough energy into a 22AWG wire to burn through a stainless braided Teflon fuel hose before an upstream fuse blows seems...quite remote to me.
But that's what I thought about the cause of the off-field landing until it happened.
1. Leaving an unused, unconfigured input pin, specifically C37-P22, physically shorted to ground.
2. Powering up a Dynon C-to-V converter (Dynon p/n 100654-000) when its output signal (white wire) is shorted to ground, remaining powered up for 15 minutes to 2 hours at a time.
I can't think up any reason for number 1 to be an issue for any EMS input. But, trying to be a hair smarter than the average idiot, I try to remember I don't know what I don't know, and ask for expert opinion.
For number 2, the converter was either disconnected from the fuel tank's capacitive plates, or connected to the tank of a Van's RV-9A, with varying amounts of fuel in it from empty to full. The C-to-V converters' outputs on my RV-9A range from ~0.9 to 1.3 V, empty to full, as read by the EMS-200's enhanced general purpose input pins. When the converters are disconnected, the output voltages are ~0.2 V.
Background details:
I recently had to rewire the C-to-V converters in my airplane after de-winging it for over-the-road transport following an off-field landing. (Long story...)
When everything was back together, I discovered the left tank converter output wire was shorted to ground. No amount of fuel in the tank changed the reading from 0.000 V. Rather than take everything apart (AGAIN!) to track down the short, I fixed it by configuring a blessedly accessible, unused enhanced GP pin, C37-P31, for the left tank level. Cutting the converter's white wire, I connected it physically to C37-P31. That left the other side connected both to ground and to pin C37-P22, now de-configured and unused.
Although both tank levels now respond to varying fuel levels as they've always done before (the right C-to-V converter was rewired correctly and worked from the get go), I would like to confirm whether some latent harm may have been done to the left C-to-V board. It should have been trying to raise its output to 0.2-1.3 V, but the current it could put out went directly to ground. Since no fuses blew, and input voltage didn't sag, I surmise the output current must be limited. What is the max output current?
It's of interest because the re-routed wire connecting P31 and the C-to-V output now goes through the fuselage next to the fuel line from left wing. Bad juju, I know, running wires next to liquids in tubing. I wrapped the fuel line with extra anti-chafe insulation, and the co-linear run about 3" at most. The probability of the C-to-V board or the EMS P31 pin pumping enough energy into a 22AWG wire to burn through a stainless braided Teflon fuel hose before an upstream fuse blows seems...quite remote to me.
But that's what I thought about the cause of the off-field landing until it happened.
