Geoff Posted January 13, 2019 Report Posted January 13, 2019 Hey guys, I just scrubbed a flight due to a low voltage indication in my 82 12 volt 231. Both the annunciation panel and the JPI 900 were warning low voltage. The JPI showed 11.7 volts and 0 amps. This was after a ground run and engine run up. Any thoughts as to what it could be? I flew the plane 1.6 hours the previous day which was the first flight since an oil change and all was well. Quote
carusoam Posted January 13, 2019 Report Posted January 13, 2019 First thing to look at... The field wire. This is the wire that the VR sends a signal to the alternator to generate voltage... If the wire has become disconnected, no signal is received... no voltage gets supplied... Common casualty of high temperature and vibration. If broken, weakened, or accidently grounded, a visual inspection may be a simple way to find the problem... find the VR, find the Alternator, they should be connected together by a few wires... one is marked ‘field’... or it’s stub is connected to the empty spot marked ‘field’... PP thoughts only, not a mechanic... Best regards, -a- Quote
Geoff Posted January 13, 2019 Author Report Posted January 13, 2019 Where is the field wire located and what does it connect to? I assume off the regulator somewhere? Quote
carusoam Posted January 13, 2019 Report Posted January 13, 2019 4 minutes ago, Geoff said: Where is the field wire located and what does it connect to? I assume off the regulator somewhere? I was editing as quickly as possible.... See the rest of what I updated above. Finding the voltage regulator in a K may be more challenging than other Mooneys... Some may be copilot side, inside firewall...behind the instrument panel...(?) Best regards, -a- Quote
jackn Posted January 13, 2019 Report Posted January 13, 2019 Like Anthony said. My guess is that the alternator is located very close to oil filter. Somebody may have knocked off(or broke) one of the alternator wires. The alternator is attached to the back of the engine just behind the oil filter. 1 Quote
Guest Posted January 13, 2019 Report Posted January 13, 2019 (edited) The alternator is low on the back of the engine. My finger is pointing at the field terminal. You can check for power at the terminal with a volt meter, or turn on the master and alternator switches, then using a few paper clips linked together to form a chain, swing them near the back of the alternator to see if its created a magnetic field. Clarence Edited January 13, 2019 by M20Doc Quote
DonMuncy Posted January 13, 2019 Report Posted January 13, 2019 On my 82 231 the voltage regulator is over the copilot's feet. 1 Quote
Geoff Posted January 13, 2019 Author Report Posted January 13, 2019 Thanks guys for all the suggestions. I wil let you know how it turns out. Quote
Warren Posted January 14, 2019 Report Posted January 14, 2019 Check the drive coupling. Mine failed last year and after lots of electrical troubleshooting I discovered that the rubber drive coupling was slipping. You can check this by trying to manually turn the alternator through the holes in the cast mounting adapter that goes between the alternator and the engine. With mine, I could turn the alternator by hand. $500 later, new coupling and it works like new. Quote
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