Xantrex multi stage regulator problem

[masonc]

I have an Amptech 12V 120A alternator with a Xantrex multi stage regulator. I found the 4ga battery wire had broken, disconnecting the alternator, so I put a new lug on it. I suspected the alternator was shot, but I tested it by putting 12V on the field wire at the regulator, with the regulator disconnected, and I got 100A at 200 rpms. I reckon the alternator is good now.

I cleaned all the connections on the regulator and put it back. I measured the field output (blue wire) as 3.6V. That does not vary no matter the engine speed. There is little or no current leaving the alternator and no increase in voltage.
The regulator goes through it's proper boot up sequence when ignition switch is turned on.There is two lights on the regulator, LED 1 & 2 after boot up.
The ground and positive wires are making good contact and have correct voltages. The brown ignition wire shows 13V when turned on.
Any ideas why I am not getting charging when running? Should I see more than 3.6V on the field output?
Thanks for any help,
Chris

[masonc]

Originally Posted by masonc

I have an Amptech 12V 120A alternator with a Xantrex multi stage regulator. I found the 4ga battery wire had broken, disconnecting the alternator, so I put a new lug on it. I suspected the alternator was shot, but I tested it by putting 12V on the field wire at the regulator, with the regulator disconnected, and I got 100A at 200 rpms. I reckon the alternator is good now.

I cleaned all the connections on the regulator and put it back. I measured the field output (blue wire) as 3.6V. That does not vary no matter the engine speed. There is little or no current leaving the alternator and no increase in voltage.
The regulator goes through it's proper boot up sequence when ignition switch is turned on.There is two lights on the regulator, LED 1 & 2 after boot up.
The ground and positive wires are making good contact and have correct voltages. The brown ignition wire shows 13V when turned on.
Any ideas why I am not getting charging when running? Should I see more than 3.6V on the field output?
Thanks for any help,
Chris

Just to follow up, the regulator was bad, even though it booted up and could be configured. Probably, the output transistors are bad.
I put in a pro reg d and I'm making 70 amps @ 1,5000 rpm. Took all day but I got it installed and working.

[tkeithlu]

Congratulations on your success in chasing down the problem. Nothing builds confidence faster than overcoming what first looks insolvable. I had one like that this morning. Forty years since I last overhauled a motorcycle engine, anxious about whether I could still do it, could not for the life of me figure out why the camshaft would not slip into place, and finally noticed that the flange at the top of the new cylinder was wider than the pocket in the head it was supposed to seat in. Wrong part.

[smac999]

3.6v would probably be normal with full batteries. basiclly the feild voltage will change from 0v to 12v to control how many amps come out of the alt based on the battery SOC / voltage.

[masonc]

It wasn't normal, the output stage was shot but as it was potted it could not be repaired. I installed a ProRegD and got my charging back immediately.