Alternator/tach problem

I don't think your problem lies at the altenator.

The tach is merely counting revs of the altenator by reading A/C voltage cycles (much like the speed sensor does in your car or truck) and converts this value to an analog readout via a "Speed buffer" at the input of the tach.

Sounds like the buffer (an electrical device at the tach) is getting hot and throwing the wrong readings.

Just guessing,

Allan

It's kinda like an electrical gear reduction box.

Hope ya get 'er going,

Allan

I'm not familiar with your exact application.

But, every one that I've ever replaced were a bolt-on little black box at the back of the tach or speed-O head.

Maybe yours is built into the tach itself, I just dunno.

It's gonna have to be a dealer item tho, because of the ratios involved for your particular model of tractor.

If the dealer doesn't list it separately, then it is internal to the tach, I would think, because that altenator lead is just an A/C tap ahead of the rectifier.

I just don't think that they would build the buffer into the altenator--but, I've been wrong before.

The parts books should call it a "Speed Buffer".

Hope this helps,

Allan