Back to the SH with VR Problem

GordoSD · Jul 27, 2009

Not long ago we got into a detailed discussion re the workings of the 6v VR. And also mentioned was the short life experienced by many on replaced VR's.
A month ago I finally deduced that I had a faulty VR on my SH. Replaced the old one and immediately saw 15-20 amps charging rate on the gauge. Happy camper. Today I started the old girl up and saw 0 amps charge rate as prior to the new VR.
Is there something in my system that can "ruin" a VR, or is it possible these new VR's can only last about 10 hours?

Gordo

Janicholson · Jul 27, 2009

A 12v generator being used to provide 6v might do it. The field coil would be regulating substantially more volts than it should. Also a 6v generator with a shorted field winding (internal short , not to ground) would also make substantial current flow through the field points. So yes is the answer. JimN

Bob M · Jul 27, 2009

I too have experienced an early VR failure on my Super H. (A new VR lasted about 5 years - maybe 60 total hours of use).

Problem turned out to be the VR's field resistor had gone way out of tolerance for no apparent reason.

However before you condemn your new VR, run through the troubleshooting chart below to determine whether the problem is something besides the VR.
generator troubleshooting

GordoSD · Jul 27, 2009

I thought the amps with the new VR were a tad high. Maybe closer to 25, but I didn't write it down. I had the genny rebuilt by a very top notch rebuilder. Is there a way to test actual amp output of the genny while on the tractor, not using the amp gauge?

Gordo

GordoSD · Jul 27, 2009

Thanks Bob. I'll run throught the cart tomorrow am and let you know.

Gordo

GordoSD · Jul 27, 2009

Thanks Bob. I'll run throught the chart tomorrow am and let you know.

Gordo

John T · Jul 27, 2009

You ask about ruining a VR, if the battery was at opposite polarity then the genny that can but it dont sound like thats what happened in your case. Para 5 of my Troubleshooting procedure tells how to easily test if non charging is a genny or a VR problem (or something as simple as either the genny or VR isnt well grounded), because I dont know from here which is the cause of her not charging. Running it and or Bobs flow chart should tell you pretty quick.

See if she charges when running if you temporarily ground the gennys FLD post cuz if it charges okay then but not otherwise, the genny is okay and its either the VR is bad or not grounded.

John T
Troubleshooting

GordoSD · Jul 28, 2009

I ran the tests. When field post from gen is grounded the amm shows 25 amps. When I ran ground wire from VR base to ground, nothing!
So it is another bad VR. Which of the points should I change to see if I can get it to work?

Gordo

Janicholson · Jul 28, 2009

25 amps output is higher than stock IH gens. Check its serial number to find out if it is OEM.
If it came from a unit that used a Higher output Gen it probably had a higher output Capacity regulator. I can't tell you a part number, but there should be several available that would work. "A" type generators are wired the same, so heavier duty would make little difference in operation, but would probably last longer. JimN

JMOR · Jul 28, 2009

(quoted from post at 14:36:11 07/28/09) I ran the tests. When field post from gen is grounded the amm shows 25 amps. When I ran ground wire from VR base to ground, nothing!
So it is another bad VR. Which of the points should I change to see if I can get it to work?

Gordo

know I'm jumping in the middle of you fellow's thread, but if you don't mind, I suggest that the test done where you shorted the generator Field to ground (& got 25A charging) be repeated except this time insert an ammeter between Field and ground and it will read field current. That would answer the question of whether or not an internal field short or even wrong field coils might be causing excessive field current that would damage the regulator's field contacts. I'm sure the other men know what that field current should be on your particular system, but as a ballpark number I expect ~2amps.

Owen Aaland · Jul 28, 2009

If your generator has a movable third brush it is possible to get them to overcharge by having that brush set too close to the other brush. There should be 3 1/8 commutator bars between the two.

Bob M · Jul 28, 2009

I agree Jim. 25 amps is way high for an OEM generator with the field grounded. (15 amps is about the max you should see - assuming of course the ammeter is accurate...)

Now with any generator setup the VR must be matched to the generator. Otherwise you risk overloading (and frying) either the generator or the regulator. That indeed is possibly why Gordo's VR's are not lasting very long.

Back to the SH with VR Problem

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Bob M

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GordoSD

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GordoSD

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