1641 voltage regulator problem
 

I just acquired a 1641 from my neighbor. He was upfront that there was a problem with the electric PTO. In troubleshooting that, I noticed that the voltage on the battery terminals went as high as 15.5 volts when I was near
maximum throttle. I backed off from that in a hurry. It starts fine and the battery voltage is 12.6 volts with engine off. At low throttle the battery reads
around 13v but the voltage increases with engine speed. So I'm assuming that
the voltage regulator is not working. My question is - does anyone know where
the regulator is - I can't find it anywhere.

Also, does anyone know where I can get a service manual. I've seen one
on Ebay which is on a CD and the seller is in France - does anyone know if that
is a good manual?

I assume I should fix the regulator problem before dealing with the PTO.

The voltage regulator is on the same side of the engine as the starter. It has two yellow wires and a red wire. The connections are twist lock.

a PDF version of your owner's manual is here:
Still looking for a service manual link.
http://dl.owneriq.net/3/3b9a8e0b-28c...4396b988fb.pdf

Update
 

Thanks for the helpful replies. It looks like I had a marginal battery. I went to
TSC and bought a full size battery. I now get 13.5v at the battery terminals
and it only varies from 13.3 - 13.5 between min to max throttle. Also, the tractor seems to run better and has a higher full speed.

In regard to the regulator, I'm still not sure. As cubs-n-bxrs pointed out, there is a unit called the Regulator/rectifier but from my electronic experience
it looks like a full wave rectifier. To me, the voltage regulator should control
the field current to the generator in order to regulate the output voltage.
I really need to get the service manual.

Here's a link to B&S alternators that I found useful http://www4.briggsandstratton.com/mi...eplacement.pdf
Page 25 of the pdf shows a general wiring diagram which seems to apply to the
1641 and there is nothing showing how the field winding is controlled. My knowledge of regulators is probably just out of date.

Thanks again.