Ford 3000 voltage regulator getting hot

[abriz]

I have a 1970 Ford 3000. I had 2 wires short out and replaced all the wiring w/a new wiring harness. Everything is working, but larger coil on back of voltage regulator was getting hot and smoking. Replaced voltage regulator, but still getting hot. Read that you may need to polarize the generator so I did that by touching wire from bat to fld. Still getting hot. Any ideas on what the problem is?

 

[Bern]

That's what the resistors on the back of voltage regulators do - they get hot. As in completely normal.

 

[M-MAN]

Check your grounds and battery
condition. Both will cause overcharging
and excessive heat.

 

[Sean in PA]

The generator is what gets polarized, not the VR, and you didn't replace the generator, only the VR, so it shouldn't have needed to be polarized again, but it shouldn't have hurt it to do so.

 

[JMOR]

(quoted from post at 08:35:34 06/04/21) The generator is what gets polarized, not the VR, and you didn't replace the generator, only the VR, so it shouldn't have needed to be polarized again, but it shouldn't have hurt it to do so.

shouldn't hurt", IF he did it right, BUT if he applied batt voltage to the VR Field terminal (not just to gen Field as in failure to disconnect gen to VR field connection), then there is a good possibility that the VR field control contacts were damaged.

 

[abriz]

How hot is normal? Old one was smoking. New one would burn your finger if you held it there but did not notice any smoking.

 

[JMOR]

(quoted from post at 22:56:52 06/04/21) How hot is normal? Old one was smoking. New one would burn your finger if you held it there but did not notice any smoking.

would measure battery voltage and verify that it is around 14-15 volts and not higher after running at speed for 5 to 10 minutes. I expect that it will be too high and caused by welding the field control contacts closed by doing an improper polarization.

 

[M-MAN]

Burning your finger is not normal. To me normal is just warm.

 

[Bern]

I've never measured it, nor have I ever stuck my fingers on one. I do know that I've seen many new VRs smoke as the shipping oils get burned off of them. So that's very likely too hot to touch.

Unless those resistors are glowing red hot and about ready to start a fire, I'd leave it alone and move on with life if the system is otherwise charging normally at 14ish volts.

 

[JMOR]

Bern or anyone else with RB340 regulator, can you measure the value of the larger (longer center tapped resistor) called "swamping resistor" . Measure from center to either end. Both ends are ground. Thank you. All wires disconnected from reg.

 

[JMOR]

(quoted from post at 12:37:29 06/05/21) Bern or anyone else with RB340 regulator, can you measure the value of the larger (longer center tapped resistor) called "swamping resistor" . Measure from center to either end. Both ends are ground. Thank you. All wires disconnected from reg.

briz or anyone with an RB340 VR handy, could you measure this center tapped resistor for me. I have been into many VRs, but this "swamping resistor" is new to me and am interested in the implementation. The other resistor (Field-to-ARM) is believed to be ~60 Ohms, but have seen no values on the 'swamping resistor'. Thank you.

 

[JMOR]

(quoted from post at 11:42:10 06/06/21)

(quoted from post at 12:37:29 06/05/21) Bern or anyone else with RB340 regulator, can you measure the value of the larger (longer center tapped resistor) called "swamping resistor" . Measure from center to either end. Both ends are ground. Thank you. All wires disconnected from reg.

briz or anyone with an RB340 VR handy, could you measure this center tapped resistor for me. I have been into many VRs, but this "swamping resistor" is new to me and am interested in the implementation. The other resistor (Field-to-ARM) is believed to be ~60 Ohms, but have seen no values on the 'swamping resistor'. Thank you.

I eventually found the answer to values and calculated the normal current thru the "swamp resistor" pair to be 0.65 ampere , thus a power dissipation of about 5.8 Watts. The old time Christmas tree bulbs were 3 Watts and are no more than just warm to the touch & has no heat sink as does this resistor via the terminal connections. If as hot as posted, then battery voltage surely must be far too high. I would actually measure at the ARMATURE, just in case the cut out contacts are not closing as they should.

 

[M-MAN]

I had to check the temperature of the vr
on my 851d just to be sure. It was a
little warm after running about 45
minutes but no where near hot. I know
this one is a different set up but
still.

 

[JMOR]

(quoted from post at 21:11:08 06/08/21) I had to check the temperature of the vr
on my 851d just to be sure. It was a
little warm after running about 45
minutes but no where near hot. I know
this one is a different set up but
still.

either should get HOT. Yours should have heat input around 5 Watts and the RB340 around 8 Watts, neither of which is significant on an item the physical size of a regulator.
I wish he had followed up, as I am still curious as to what was causing such heat as he described. It just about has to be too high a voltage at armature.