127 Generator Question

proctoidpaul · #1 05-04-2020, 02:28 PM

I'm putting a 127 back into light duty service. After some other work and/or open quesitons, I'm down to a question now about the electrical system.

After a good charge on the battery, the engine starts up fine and quick. But I don't get any charge indication on the dash meter. Doing a voltage check the battery is around 12.6 volts whether engine is running or not.

I would expect the voltage to be higher when running. If anything it's slightly lower when running. So I suspect the generator side of things isn't working right.

I've tried testing voltage at the posts on the top/rear of the generator, but don't seem to get ANY voltage there. I haven't run it a lot. Maybe 30-40 minutes after last battery charge. And the battery seems to be holding its charge, but how can I confirm if the generator is actually working? (I know it's a dual purpose starter/generator... not sure what the actual technical term is for this.)

R Bedell · #2 05-04-2020, 03:21 PM

AS A TEST.....

Take a Jumper Wire and place it on the "F" terminal of the Voltage Regulator. With the other end of the jumper wire, touch it to the frame of the tractor for a second or two. Pay attention to the Amp Meter. Report back.

proctoidpaul · #3 05-04-2020, 04:17 PM

Quote:

Originally Posted by R Bedell

AS A TEST.....

Take a Jumper Wire and place it on the "F" terminal of the Voltage Regulator. With the other end of the jumper wire, touch it to the frame of the tractor for a second or two. Pay attention to the Amp Meter. Report back.

I saw some mild sparking at the point of grouding the wire to frame, but no change in the Amp Meter.

Sparking was similar as that when [properly] connecting a battery charger.

I confirmed I was on the "F" terminal. Other terminals on that side were stamped "BAT" and "GEN". Opposite side had the "GRND"

R Bedell · #4 05-04-2020, 04:34 PM

If you did as I instructed, and the Amp Meter didn't peg to the Charge position, then the issue lies with the Starter/Generator. Take it off the tractor, and take it to a reputable Electric Motor/Generator repair shop, and have it checked out.

RLause · #5 05-04-2020, 05:47 PM

I would put the wire on the field terminal of the generator and eliminate a potential bad wire between the regulator and generator and repeat the test.

crazycubtrio · #6 05-04-2020, 09:40 PM

You could also do a quick bench test of the S/G by removing the belt and all wires from the S/G then using either a jump pack or jumper cables( should only need one if the S/G is still grounded good,) but touch battery positive to the ARM terminal and give it a few seconds to get up to speed. Immediately touch it to the F terminal and see if it slows rapidly. If it does for the most part your S/G is good and the problem lies elsewhere . Done this many times and will tell you instantly if the charging side of it is not working. Hopefully it is a pesky regulator instead- lots less expensive

proctoidpaul · #7 05-07-2020, 01:13 PM

Quote:

Originally Posted by crazycubtrio

You could also do a quick bench test of the S/G by removing the belt and all wires from the S/G then using either a jump pack or jumper cables( should only need one if the S/G is still grounded good,) but touch battery positive to the ARM terminal and give it a few seconds to get up to speed. Immediately touch it to the F terminal and see if it slows rapidly. If it does for the most part your S/G is good and the problem lies elsewhere . Done this many times and will tell you instantly if the charging side of it is not working. Hopefully it is a pesky regulator instead- lots less expensive

Yeah, I saw this test other places... and according to this, the S/G is good.

I also tested bypassing the "F" (field) wire, and that made no difference, so it's not the "F" wire.

I guess that points me to the VR? If so, what do we know about compatibility with other VRs? ie: I just put a new VR on a 57 Oliver tractor... only to later convert it to an alternator. Are all VR created "equal", or would I need to get one especially for this since it is a combined S/G?

Paul

proctoidpaul · #8 05-07-2020, 03:43 PM

After carefully reading up on "polarizing" a VR, I installed a new regulator (taken from a my Oliver Super 55 which didn't need it any more) and installed into my 127. After polarizing, it began working immediately upon start up.

After reading various posts about needing to polarize these things after dead/replaced/disconnected batteries, I wonder if that was actually the problem. This thing sat unused for a few years and the battery was definitely 100% flat.

If you're reading this for your own consideration in the future, here are key points to watch out for.

If you're not replacing with an exact replacement VR, be sure to follow the markings stamped on the VR leads. They very well may not be the same as the original.

In my case, "F" was the same position on the right, but the "GEN" from original became the back side terminal, which was not marked and I had to determine based on process of elimination. BAT moved from the left terminal to the middle, and I didn't need "L" (Load).

I found a quote in another thread here directly from a CC manual, that to Polarize the VR, quickly jump from + side of battery to the "GEN" connection (wherever that is) with everything fully connected, but not running.

You get a pretty good spark and you just need a quick touch. Definitely don't want to hold it there.

If I get time, I may put the old VR back on and try polarizing it, just to see if that was the real issue.

Thanks for all the tips and help!

Paul