Voltage Regulator Cutout Relay

M

mrboch

Junior Member
Hey all, hopefully someone can point me in the right direction...

My '40 pickup is not charging. Generator has good output (as measured when I tie the field & arm terminals together and measure the voltage of the armature), but appears cutout relay contacts are not closing to charge battery.

Any suggestions?
 
I looked at a drawing of a cutout awhile back,there is a smaller winding wound under the larger windings,the small winding is the one that pulls in the relay that closes the points on cutout,might check the connections on this small winding,just a thought...
 
The residual magnetism of the generator field poles pulls the cut out contacts together after start up so it could just need a flash of the field to repolarize. If polarity is off it won't work. The cut out coils or points could have given up the goat too. I assume this is a two brush generator with a three pole regulator if it's a 1940 model.
 
Do this test. Leave the generator armature wire connected at the regulator. Remove the field wire from its regulator terminal and connect it over to the armature terminal. Start engine and rev it up and see if the cut out contacts close and check the dash ammeter which should be charging high. What this test does is bypass the voltage and current regulator but still has the cut out in the circuit. Report the test results. Regards, Kevin.
 
To confirm, yes this is a "standard" 2 brush, 3 pole regulator setup. Also polarized generator previously (field wire to battery).

I did perform the test recommended by koates: at idle (which is ~ 650 rpm for a different reason), I get ~ 7-8V to the battery (measured at that BAT terminal on the regulator). I also see the amp gauge on the dash show charging at the same time.

Does that imply the current regulator is bad?
 
It would appear that the contacts in the voltage regulator (the end one) or the current regulator (the middle one) are burnt and worn. Also when testing generators and regulators you need more than idle or 650 RPM. Bring up to around 2000 RPM. 7 to 8 volts is OK but when adjusting regulators you need to be specific in the reading, like 7.6 volts would be good. 8 volts is too high. Contacts can be dressed carefully with a points file and fine wet and dry paper to get e smooth finish. Re setting the voltage and current can be tricky if you don't have experience in this work. Another requirement is a good quality analogue (has a pointer type dial, not digital) volts and amps automotive test set. All settings have to be accurate and to specs and near enough is not good enough. Regards, Kevin.
 
Thanks for the help! I replaced the regulator & everything is working as expected with 7.5 volts solid going back to battery. Yeah - I have an old Penske analog tester - one of the best tools around.

Now to get it back on the road!
 
That's good news. I had exactly the same problem this summer. Rather than messing around with the existing regulator, I replaced it with one from Mac VP and all is well.
 
mrboch, That's good news your charging system is fixed. Its easy when you know how to test the system. Regards, Kevin.
 
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