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Fuse Failure on Switch/Fuse Module

Kip

Member
Has anyone had the 1 amp fuse on the AV-50001 Switch/Fuse Module that goes to pin 16 (VREG) on the connector fail? If so, what do you think caused it to fail - inadvertent short? What is the fuse intended to do - protect the wire in the harness and on to the master switch? More importantly, how did you fix it? It is soldered into the board and not intended to be replaced!

If I am not mistaken this supplies voltage through the master switch to the control pin (C) on the Ducatti voltage regulator, which won't function without voltage to that pin.

There has been talk about placing a jumper wire from pin C to the Batt++ terminal to solve this (apparently as is done on the Silent Hektick regulator). But does this have some negative consequences? I'm considering placing a jumper wire around the fuse on the board and then installing a small 24 ga wire on the harness outside on the module as a fuseable link, or maybe a replaceable 1 amp fuse. Thoughts?
 
Mine failed when my Ducati failed. I don’t know which was the cause and which was the consequence. Van’s Builder Support told me the fuse was added — it wasn’t in the original design — because some builders had fried their entire systems while bench testing their systems during the building process. I replaced the entire Switch/Fuse Module.
 
Yes, RV-12 owners have inadvertently shorted the wire going to regulator terminal C and
have blown the 1 amp fuse. You are correct that terminal C gets voltage from the master switch.
Do NOT jumper from terminal C to terminal B ! !
If there is smoke in the cockpit, shutting off the master switch will NOT shut off the
alternator. Your stinging smoke filled eyes will not be able to see the 30 amp fuse to pull it.
The correct fix is to install an inline ATC fuse near the voltage regulator. Connect
one lead of the fuse to regulator terminal B. Extend the other fuse lead through
the firewall and connect it to the 8 inch long white/yellow wire that goes
between AV-50000A ignition pin 13 and AV 50002 pin 13. The circuit might now
look different, but is electrically identical to the original circuit.
Notice that the light on the master switch now works.
If you do this modification, let us know how well it works.
 
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I blew that fuse while doing avionics upgrades to my RV-12. I installed the auto-pilot control module, knob module, ADS-B receiver, 2020 GPS, put a new stick grip on with pitch trim, put a double usb outlet on the panel. I did not know to disconnect the battery ground cable before I started. So I think the cause was something shorted while I was working and it would have been avoided if I had disconnected the battery ground cable. I did all this in July 2018 and did the test flight after finishing the day before I was going to fly to Oshkosh. On that flight, the battery was not charging and it was late on Saturday afternoon. So I had to choose between staying home and trouble shooting the issue or driving to Oshkosh. I drove to Oshkosh and did the trouble shooting when I got home.


There is disagreement on how to fix this. On the new aircraft with the SH voltage regulator, Van's suggested wiring is to jumper the two cables on the voltage regulator. That is what I did to fix mine. I did that in August 2018 and it is still that way. When that 1 amp fuse blows, the LED light on the Master Switch does not work. I took the panel out, ordered some 1 amp fuses from Amazon, and a flying buddy who is into electronics soldered a new fuse in for me. Now the light on the Master Switch works but I left the VR terminals jumpered.

I have read that Rotax suggest jumpering the two terminals on the VR as their suggested wiring. I realize that if an electrical fire starts, that I have to turn off the Master Switch and pull the 30 amp fuse.

I am comfortable with my aircraft with the two terminals jumpered. But some on here are not. So I think you just have to make a choice on which way you want to fix it. If you want to replace the fuse, you can send it back to Van's and they will fix it. If you do it yourself, when you get the fuse module out, you have to take it apart and you have to be very gentle during this process.
 
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