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over voltage cessna 172

2009-09-19 23:23:56

over voltage cessna 172

hi

i am so frustrated, i am having a hard time remaining calm.

i picked up my plane from the avionics shop after having a garmin 420 installed (took three weeks to install). i now have an over voltage problem in a 1972 cessna 172 L . the needle is pegged on +60 amps. when i turn on lights, strobes, and pitot heat, the needle goes down to about + 30 amps. this is totally backwards from what i would expect.

anyone have a reason why i may be experiencing over voltage?

sincerely

a very frustrated kyle

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2009-09-22 00:25:27

Re: over voltage cessna 172

sounds like you have a regulator and/or alternator field wiring problem.

I would have thought the over voltage protector would have opened the field circuit and the OV light come on. If this hasn't happened, and the fault arrived with the avionics work, suspect they messed up some wiring behind the instrument panel.

Quick check - engine off, turn on the master switch then turn off the alt side of the switch. the OV light should come on. This doesn't tell you much if you didn't check it before, but it is what is supposed to happen.

two components in the field wiring 1. the voltage regulator located on the firewall and 2. the over voltage sensor/cutout, usually tyraped to the wire bundle above/forward of the main breaker panel.