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Help with alternator diode

Icarus

Well Known Member
While cleaning my -4 up for its CI I felt a wire behind the alternator give and found a cracked diode on a wire going from the B lead to another alternator stud, pictured.

I am unable to identify the diode as the sheath got busted up. Frankly, I can't even identify the alternator. Works great with an external VR, never any hiccups.

Anyone recognize the alternator or know the diode specs? Bonus points for confirming what it is actually doing there in the first place.

Thanks gurus!

Paul

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Diode

Looks like this is a diode to protect against inductive kick. Goes from positive to ground. I cant read the number, but am wondering if a 1n5811 would work?

I will wait for the experts to chime in.
 
Possibly a zener diode, added in a misguided attempt to clamp any overvoltage event. In any case, unneeded for proper alternator operation. But.

Do you have overvoltage protection? Hint: Aeroelectric Connection.

Charlie
 
Zener diode?

If this is zener diode, then needs to be removed and not replaced. If a zener here every tripped, it would probably instantly blow apart and be useless. What is the design of the rest of the electrical system?
 
I agree with PilotjohnS. Read the pdf from Aircraft Spruce. The device needs to be in series with a fuse or circuit breaker. Without over current protection, the new device will just blow apart again.
 
Careful with terms. The transorb is wired as a shunt to ground after the protection; not in series in the circuit.
 
Like Charlie said, and I did not express clearly, the transorb is in parallel with the load.
The combination of load and transorb need to be in series with a fuse or circuit breaker.
The transorb should not be in parallel with an alternator output unless it is rated to
carry full alternator output, which is unlikely.
 
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