oops, fried regulator?

[Wheels]

Ok, here it is on the forum for all the world to see. I bought a battery to start my kit fox 1200 with a rotax 912. The terminals were backward to the one I pulled out and I didn't notice the orientation difference. At first start the starter ran backwards! Just the starter, not the prop. I didn't make a second attempt. I was in shock. I investigated, corrected it, started the engine and the VOLTMETER reads zero. the fuses to the voltmeter and the voltage regulator are visually fine. But I suspect I fried the voltage regulator. Can I test it? How? I have a fluke meter but never have learned the finer points of electrical troubleshooting. the learning curve is high today.

[HighWing]

I am definitely not the expert you are looking for, but it would seem to me, that even if the regulator is fried, your panel volt meter should read the voltage it is connected to - the voltage output of your battery. What does it show with the master switch on and the engine not running. That is the first thing I would check with the Fluke to see if it and the panel meter are reading the same. If it shows a voltage, I would leave the clips on the battery and start the engine and then see what it reads. If it is the same, the regulator could be gone. If it reads a higher voltage, it would suggest the regulator is charging the battery. How to check the regulator with the Fluke? I have no idea.

[Wheels]

I was flying one time when I lost the voltage regulator. the volt meter just went to zero and stopped charging the battery, so when I replaced the regulator, the voltmeter showed the charging system at 12+ volts again. So, that being said, I think its possible to lose one and not the other, but I am going out to start the plane and see if I can read voltage with the fluke.

I'll keep you posted.

[Av8r_Sed]

If you've got a protection diode on the starter relay (most likely), it may have fried with the reversed polarity. It may be now acting as a short circuit and your regulator output protection could be triggered.

Many multimeters have a function to check diodes. See if you can isolate the diode from the coil and test it. Also check any other protection diodes on relays in your system. Hopefully you haven't toasted anything too expensive. Fuses only protect against overcurrent. They may not help you for reversed polarity.

[Wheels]

Thanks for the tip on the possible diode problem. I'll search the threads here and rotax owner. com and see if there are any "short schools" on troubleshooting. I went to get the fluke meter and didn't find it but do have a multimeter, (im reading the manual.)

[n85ae]

Don't get led astray with "Fluke" meter, etc. This is not the issue. This could
could be troubleshot with the cheapest meter you can find. Or even in a
pinch with a flashlight bulb, a battery and a couple wires ... Seriously
this is not the issue.

These light aircraft electrical systems are super super simple, however
that is because I have an electronics background. The questions you are
posting suggest that your background is probably something else.

Really the best advice I can think of - Is that you should seek somebody
who has an electrical/electronics background to help troubleshoot your
problem in person.

This is not meant to be insulting, but troubleshooting like this is very simple
and making a really minor mistake can end up doing a lot more damage (i.e.
smoke, etc).

Get somebody with experience to help you in person, NOT a forum. Contact
your local EAA chapter, I'm sure they have somebody who would run over
and help out for free.

Regards,
Jeff Hays

Thanks for the tip on the possible diode problem. I'll search the threads here and rotax owner. com and see if there are any "short schools" on troubleshooting. I went to get the fluke meter and didn't find it but do have a multimeter, (im reading the manual.)

[Wheels]

A local builder from the Eaa chapter is coming over tomorrow to put his multimeter on some components. I appreciate the idea, He offered to come over as soon as I called. Thanx to you for your insight on both the electrical and the human.

[n85ae]

That's the best idea. Hopefully it turns out to be just a smoked rectifier/regulator. Seems like a logical component to fail if the battery
was reversed.

Jeff

[Wheels]

I am still not done chasing the problem, but the guy with the multimeter knowledge will be here tomorrow. I started the engine and did all the checks. Everything looks and sounds great to WOT. but I need to deal with the prop pitch. Its to deep. I had good checks on all so I took to the sky for the first flight since beginning the refurbishment. All went well. The plane picked up at least 10 mph with the wing strut fairings. the wire that I connected in the ICS was the power wire, so now THAT works. My wife will be able to tell me how Im flying. I have started the motor about 15 times and no apparent drain on the battery. I am beginning to think the voltmeter in the cockpit is all that got fried. but will check it tomorrow. I have a new regulator on order anyway.
Thanks for the help. pics soon.

[Wheels]

Ok, still not done. My multimeter wielding friend couldn't come over.
I replaced the Voltage regulator because I could. I have one. The plane starts fine and runs well. the voltage meter in the cockpit reads Zero. It should be reading 14 +. I removed the voltage meter and cleaned the grounds when I replaced the regulator. The voltage meter is one of those 18.00 dollar units they sell at Autozone and everywhere else. I took it with me to match the size and type and the salesman at the store put a multimeter on it. (God bless that boy)
It checks good. So he hooked it up to a battery. It showed 12 volts! its fine!
He then reversed the leads to show me that it will read zero if hooked up backwards. it read zero when hooked up backwards.
Do I dare hook it up to the plane and reverse the leads to see if that is indeed the problem? the wires in the plane are not marked, the posts on the meter are marked. I wish the wires were not in such a crazy tight bundle but they are a bundle and chasing one wire to see if it is the hot or ground looks like a wiring nightmare. Ideas? or can I go with plan "A" and hook it up opposite to what I had before and see it that is the gremlin? Thanks in advance.