preinke

Alternator troubleshooting

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The alternator that came with the factory reman engine installed a year ago went offline on the last flight. I assumed it was TU but it came back on , on the flight for annual but went back offline when I put the gear up. I put the gear back down right away but dumped some load and reset the field breaker and it stayed up the rest of the flight. I have the Zeftronics 15300 regulator that I assume didn't like field resistance or the bus overvoltage but I don't think there is an indicator of which condition knocks it off. We checked field voltage (10.6) and resistance (5 ohm) on the ground . Didn't turn the alternator through to see if there were any field current irregularities. Looked the wiring over and observed the "brush block" seemed to flex. Was going to clean master terminals per DMax but am not hopeful. A&P thinks its the regulator - I think its the alternator - probably neither ! My ammeter doesn't work - anyone know where it is  and the fuses on a 1977 J ?

Paul '77J KIKV

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Can you spin the pulley by hand? Check the belt tension maybe. 

-Matt

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The ammeter shunt and fuses are next to the regulator on a shelf behind the tach.

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Field wire is often a loose connection causing some challenges with charging...

PP thoughts only, not a mechanic...

Best regards,

-a-

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Any thoughts on the connector / brush  block being movable ?

 

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Are you referring to the brushes inside the alternator itself as those are only accessible after disassembly.  

 

The stud that connects 12VDC+ to the battery can be a little loose as it has a square shank that mates with an insulating materials though the case; typically not an issue.

 

I second checking belt tension or glaze on the belt. I had something similar on the standby alt on my K. It went away with a belt change and the belt was pretty cracked and shiny.

 

iain

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The bruses come out easily and are easy to change on the aircraft. I had an alternator that needed new brushes every annual. Eventually figured out a bearing was going out. 

-Robert

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