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Voltage Regulator Failure Mode (deja vu)


FastEddieB

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A few weeks ago I started my Sky Arrow for a trip to Knoxville and the VOLTAGE light stayed on at my normal 2,200 rpm or so after engine startup. However it went out and stayed out after I goosed it to about 3,000 rpm, and it stayed in normal mode for the trip up and back to Knoxville.

 

Yesterday, I went to fly with Karen to Dalton, GA and after engine start the light just stayed on - drat!

 

This happened once before, details here: http://ctflier.com/index.php?/topic/330-rotax-912-voltage-regulator-failure-mode

 

I'm going over to the hangar today to troubleshoot connections and grounds. If that fails I have a spare voltage regulator I'll try. Its the stock Ducati part. At least its far easier to access after my aforementioned relocation of the voltage relay.

 

Do I remember that someone is making a more reliable replacement? I tried Googling and could not find anything (though my prior thread was the first Google hit!).

 

If its not one thing...

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Hi Eddie,

 

I'm not saying the reg/rec never goes bad, but they are pretty reliable and failures are few. It is usually a bad connection or broken wire. While your looking for a bad connection make sure you pull on each wire going into the reg to make sure it is seated and locked in place. It is a common problem when anyone has disconnected the reg. at some earlier time.

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I'm not saying the reg/rec never goes bad, but they are pretty reliable and failures are few.

 

Funny, I thought they were notoriously unreliable.

 

It does say "DUCATI", after all!

 

Headed over to the hangar shortly and I'll tug on a bunch of wires.

 

Do you think a loose wire could cause the voltage regulator to burn out? And do you recall the possible alternative to the Ducati part?

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Follow up.

 

I started the plane to verify the problem was still there - it was.

 

I pulled the cowling, removed the voltage regulator and applied some Stabilant-22 to the lugs. Reassembled and I was back in business.

 

Still, I pulled the plug again and cleaned up the lugs and ran some sandpaper into the plug sockets and then sprayed some contact cleaner in.

 

The only thing suspicious is what looks like a small burned area on one of the lugs:

 

6795714442_c31957734b_z.jpg

 

Is there an easy way to tighten up the sockets? I'm thinking it may be a slightly loose fit that keeps causing this to recur.

 

6795713848_646851604a_z.jpg

 

Again, its always something

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Heat and vibration can make these connections loose. I had a problem with this on my fuel pressure sender between corrosion on the VDO sender and very loose spade lugs. It's much more criticalon the reg since these connections need to handle up to 20 Amps. You can crimp snug them with pliers but also, I would use some pro-gold contact preservative on them

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You can crimp snug them with pliers but also, I would use some pro-gold contact preservative on them

 

I'm a bit naive on this kind of connector. How does one access the connectors in order to crimp them?

 

And what is pro-gold? Stabilant-22 is the weapon of choice in the Cirrus world.

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Hi Eddie,

 

See the tiny square slot just above each connector. Slide the small tip screwdriver that Kurt mentioned into that slot. It will depress the barb inside and release it. When you go to put it back in make sure you push the little tab on the connector back up above the connector's plane. Then when you push it back in place you should hear it click and if you pull on the wire it should be locked in place. If you had a loose connection it can absolutely burn this connector and wire up. When you push the whole connector back onto the reg/rec push it very hard with both hands to make sure all connections slide in place and make a good connection.

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I have had problems with wildly fluctuating current,ie, the amps can go from +10 to -10 and everything in between with high and low current alarms 2 to 3 times in 5 minutes. We checked the ground connections, the shunt, the ground post , changed the battery, and the voltage regulator rectifier, and tightened bolts all over. I notice my battery voltage may start at 13.4 (it is on a charger all the time) but goes up and down to 11.5 as this amp fluctuation occurs, albeit not quite so wildly. Nothing appears loose but it sure acts like something is loose. Looking for suggestions.

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