resistance measurements on a VR

55 50 Ron

Well-known Member
Has any one made resistance measurements on a 4 terminal regulator off the generator and no wires connected between any terminals. Wondering
if any one actually troubleshoots a VR that way or is it more common to just swap in a new one if the old one is suspected of being bad?
I'm working on a 12 volt positive ground system on a JD 2 cylinder where I think the 4 terminal regulator may be bad. Generator charges
nicely with field terminal "grounded". Thanks folks.

Nice rain here last night in southern MN.
 
IIRC, the resistors in the old Delco regulators typically had the resistance value stamped into the tab at one end of the resistor.

I would expect each wire-wound resistor to be either very close to it's original resistance or "open".

That being said, very likely your problem is dirty contacts in the voltage/current control relay(s).
 
Usually the most common problem is dirty contacts. They can be filed (not sanded), and cleaned with contact cleaner. If you can get it to work at all, then it can be adjusted if needed. That is a tedious job, and will change when the cover goes back on, so only go there with guidance and patience.

Saving the old regulators should be attempted IMHO, as the new aftermarkets are not near the quality.
 
(quoted from post at 16:21:23 08/17/17)

Saving the old regulators should be attempted IMHO, as the new aftermarkets are not near the quality.

Boy, I'll second that. I actually rate them as junk.

RT
 
Ron, other then actual internal "resistors" located inside the VR which may be labeled as Bob M noted, I doubt ohms readings on the VR is going to locate the problem. If any of the contacts are closed there would obviously be near zero ohms across them. If not Id try to clean/buff/polish as non abrasive as possible to see what happens. I'm sure you are familiar with my Charging Troubleshooting which can easily show if non charging is the fault of the genny or the VR right???

John T
John Ts Troubleshooting
 
Right, and as I mentioned, the genny is charging nicely with the field terminal at "ground" (generator chassis)
 
Also, the regulator has to be grounded. If yours is rubber-mounted there'll be a braided copper strap jumpered across the rubber mount. They sometimes break.
 
Resistance from field terminal to regulator ground should be zero ohms. If points are burned or bad resistors or windings, you will get some kind of reading above zero.
 
If it charges with the field grounded it means the reg is bad so just get a new reg for the delco remy # on the gen polarize the genand you should be good to go.
 

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