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  #21  
Old 06-20-2017, 11:38 AM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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The Rotax dynamo will keep on working even if the battery is disconnected. However without the battery, the voltage will not be stable and vary up and down about 3/4 of a volt from its setpoint. That causes the Dynon to give a voltage alarm. The voltage regulator does not think that the voltage is low because it monitors electrical system voltage, not battery voltage. The regulator does not call for full output. The electrical system voltage is still around 14 volts, plus or minus one volt. All electrical loads are still powered by the dynamo like they always are, whether the battery is connected or not. The trim worked because it was powered by the dynamo.
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  #22  
Old 06-20-2017, 03:57 PM
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Piper J3 Piper J3 is online now
 
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Update: Iím still verifying wiring while waiting for the new Master Relay from Vanís. I was convinced that the AV Control Board 12 (fuse/switch assembly) was unharmed even with electrical smell (see post #1). Well I guess it was fake news or alternative facts, because the master switch isnít working.

I removed the sheet metal protective backing on the circuit board and can now see where the foil tracings have lifted from heat. This is not an easy fix because the tracings are inaccessible as two circuit boards face each other and cannot be separated.

The solution is to replace the entire assembly. Iíve called Vanís and they stock the part but the cost is prohibitive. Iím wondering if someone might have one of these assemblies lying around. Perhaps someone built their own panel or installed a different engine and didnít use the AV Control Board 12 that was furnished with the kit.

Let me know if you have an AV Control Board 12 and we can work a deal. Iíll also post an ad in the VAF Classified Thread.

Thanks for listeningÖ

Direct email is strickjc@frontier.com
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Jim Stricker
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80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 288
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  #23  
Old 06-20-2017, 08:53 PM
rv7charlie rv7charlie is offline
 
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I'd tentatively agree with Mike, pending more info about what's actually on those circuit boards. You do need to determine what overloaded that trace.

Does Van supply a *complete* schematic for the a/c, including all the interconnections on that module? If so, it can possibly be repaired. Separating the two boards, & repairing the burned trace, shouldn't be too hard for an electronics tech.

If you have good docs & you want to give repair a shot, send me an email with some more pics. Try to show the burned trace & how the boards are married to each other.

Charlie
mcsophie@gmail.com
(electronics tech in a couple of former lives)
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  #24  
Old 06-22-2017, 03:48 AM
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Piper J3 Piper J3 is online now
 
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I installed the new Master Relay with my new wire that controls it which I soldered to the back of the master switch. Success. Master Relay pulls in and reference voltage shows up at the voltage regulator.

Engine runs and voltage regulator works so main problem is solved. Both ignitions working. Avionics and EFIS are working.

All functions working accept the following:

• Master switch LED indicator does not work
• No LED’s working on any of the panel switches (avionics, landing lights, etc)
• Trim motor not working - fuse OK
• Stall warning not working - fuse OK
• Audible warnings in headset not working

My question - is there something in common for all these items to not have power? Does the master switch also power these items and the fact that it’s own LED doesn’t light mean its not passing power to these other items? When I had power surge from the defective Master Relay could it have damaged the master switch in a way I can’t detect with an ohmmeter? My suspicion is the master switch has an internal fault. I’m also thinking maybe sensitive electronic components got damaged.

Beginning to look like I need to replace the entire Control Board. Anybody have a Control Board left over from maybe a panel upgrade or engine conversion requiring different controls?

Again, any help appreciated…
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Jim Stricker
Hinckley, Ohio
PPL - 1970
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC 7/12 Bought Flying 10/2015 with 48TT - Hobbs now 288

Last edited by Piper J3 : 06-22-2017 at 04:01 AM.
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  #25  
Old 06-22-2017, 04:29 AM
BigJohn BigJohn is offline
 
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Jim, so sorry for your problems. It is beginning to look like the surge cooked several of the more sensitive electronic components, such as the dimmer circuitry, trim servo, audio circuits etc. some of the electronic gurus can weigh in on this, but that's the way it seems to me. Even if you were able to replace/repair individual components, I think tou need to ask yourself if you want to fly behind a module that has been subjected to this kind of abuse.
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  #26  
Old 06-22-2017, 04:29 PM
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Tommycat Tommycat is offline
 
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Mike,
Thank you for that excellent schematic!

Quote:
Originally Posted by Piper J3 View Post

I installed the new Master Relay with my new wire that controls it which I soldered to the back of the master switch.

It may be helpful if you where to draw on the schematic where the trace was burnt, and where you installed the repair wiring.


My question - is there something in common for all these items to not have power?

I would suspect it's not about having power...but having a good ground.


Does the master switch also power these items and the fact that it’s own LED doesn’t light mean its not passing power to these other items?

The master switch itself only supplies power to terminal 1 when ON, which is connected to the voltage regulator C terminal for voltage sensing and the LED anode for operation indication.


When I had power surge from the defective Master Relay could it have damaged the master switch in a way I can’t detect with an ohmmeter?

Possible...but unlikely. You could also try a light probe tester. But remember always isolate the components when troubleshooting. And that this switch internally has 2 different switches, that control 2 different circuits.


My suspicion is the master switch has an internal fault.

It pulls in the master relay, and the regulator is working properly...it's two jobs in life. If the LED is rated at 12 vdc, grounding terminal seven, with switch on should light the light. Verify rating and isolate before trying...

I'm sticking with damaged or missing ground.


I’m also thinking maybe sensitive electronic components got damaged.

Innocent until proven guilty.
Lots of wires and pins here... I would recommend re-seating every connector paying particular attention to P2, a PCB interconnect and double checking grounding wires,pins, and connections.
If needed I would pick out the easiest circuit not working to troubleshoot, and go from there.

Best regards,
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Last edited by Tommycat : 06-23-2017 at 06:23 AM. Reason: Not sure of LED rating...
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