Alternator/Voltage Regulator - 19Volts?

[RONSIM]

Week-ago Friday flew the -6A for a couple of hours. On Saturday morning, buckled in, started up, and (apparently) dead alternator. No problem, I had my "new" spare Advanced Auto Parts #13030 on the shelf. After 15 yrs of faithful service, it was time to give the old one a rest. I had to take the new one to the (aircraft) alternator shop to change over the pulley (took an impact wrench to get the nut loose). While there, the new one was put on the tester and deemed good to go. Left the old alternator for a rebuild.

Installed the new alternator and fired up the engine ---- still no joy! So, I figured the voltage regulator (Transpo P8-405A)was bad (after checking wiring and ensuring power was getting to the voltage regulator, but nothing coming out). NAPA store was able to match the VR, after some searching, and ordered one.

Today, I installed the new VR and fired up the engine --- good thing I had nothing turned on ----- Voltage output immediately jumped to 19 volts (as measured by two different voltmeters). Immediate shutdown and no apparent damage. The VR, according to the literature, was set for 14.2 volts.

I have ordered another VR, but looking for any other ideas?

Ron

 

[Mich48041]

Look for a bad connection in the regulator "SENSE" circuit. Possible suspects are the alternator switch (could be half of master switch) or field circuit breaker. Problems will show up better with the circuit loaded with an automotive light bulb. Voltage at the regulator SENSE terminal should equal battery voltage.

 

[RONSIM]

Update

Everything I checked still pointed to the voltage regulator --- since the one from NAPA had no markings, the box looked like it had been opened and beat up, I suspected that they "matched" my voltage regulator by picture only. I went to my local "aviation" alternator repair shop and talked with them. They actually had three of my exact voltage regulator, new, lying on the bench. Two were adjustable and one was fixed. The shop tested each of them right then, while I watched. All tested good, so I bought the "prettiest" one.

Anyway, back on the airplane, all circuit breakers pulled (except starter), and fired it up ------- perfect, 14.4-14.6 volts, steady. I started putting breakers back in, and adding load ----- all good!

I get to go flying tomorrow!!

(NAPA refunded my money)

EDIT: --- By the way, I am convinced I destroyed my voltage regulator by turning my alternator off and on several times while I checked my B&C "standby" pad-mounted alternator.