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Generator Circuit #1310917 Thu May 16 2019 04:37 PM
Joined: Nov 2000
Posts: 1,601
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Frank50 Offline OP
Shop Shark
Is the 6 volt generator circuit in a pre-55.2 Chevy truck Delco "A" or "B"? If you know which, please explain the difference.
I should probably know this already.

Thanks

Re: Generator Circuit [Re: Frank50] #1310929 Thu May 16 2019 06:31 PM
Joined: Feb 2004
Posts: 18,832
H
Hotrod Lincoln Offline
Boltergeist
All the 6V and 12V General Motors charging systems I'm aware of are "A" circuits. The difference is where the windings of the Field coils get their ground. In an "A" circuit, a slight voltage (about 1/2 volt) generated by the residual magnetism of the armature is picked off by a field coil winding, and sent to the voltage regulator. There, it finds a ground by passing through two sets of points, the "current regulator" and the "voltage regulator". This field current causes the armature to develop more voltage by setting up a magnetic field in the generator housing. This voltage rise continues until either the current or voltage regulator points open and prevent the generator from damaging itself, or the battery. This point opening/closing cycle happens several times a second as either maximum current flow or voltage is produced.

A "B" circuit system has one end of the field winding grounded inside the generator housing, and the regulator provides voltage from the armature via the regulator wiring (not a ground) to make the field circuit operate. Once max output is reached in either current or voltage, the control points work the same way- - - -they're just interrupting the current flow to the field coils instead of opening and closing the ground path. Virtually all Ford generator/regulator systems and a lot of MOPAR systems use the "B" circuit.

To test an A circuit generator to see if it's been polarized properly, with the engine running at a fast idle, disconnect the "F" wire from the regulator and touch it to a good ground such as the regulator base. The generator should go into max output, controlled only by the speed of the pulley. To test a B circuit, disconnect the F wire and touch it to the BAT terminal. Do this only momentarily, and don't run the engine much above a fast idle while testing.
Jerry



The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: Generator Circuit [Re: Frank50] #1310943 Thu May 16 2019 08:31 PM
Joined: Nov 2000
Posts: 1,601
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Frank50 Offline OP
Shop Shark
Thanks Jerry.

Re: Generator Circuit [Re: Frank50] #1310953 Thu May 16 2019 10:04 PM
Joined: Aug 2018
Posts: 154
D
drdoug Offline
Shop Shark
Next step beyond Jerry's good summary - if the generator needs to be repolarized (such as may happen after the battery has been disconnected or V regulator changed), the procedure is simple. Momentarily jumper the Bat and Arm (sometimes labeled Gen) terminals at the V regulator. That causes current to flow which will polarize the generator... but you probably already know that. Image from the old Delco 1R-117 attached; procedure in the lower right column.

Attached Files
Delco 1R-117 pg 3.jpg (385.61 KB, 101 downloads)
Re: Generator Circuit [Re: Frank50] #1310970 Thu May 16 2019 11:54 PM
Joined: Sep 2001
Posts: 28,313
tclederman Offline
Boltergeist


Tim
1954Advance-Design.com
1954 3106 Carryall Suburban - part of the family for 48 years
1954 3104 5-window pickup w/Hydra-Matic - part of the family for 14 years
Z-series (54/55) GMC 350 (2-ton) COE - now part of Dave's family
- If you have to stomp on your foot-pedal starter, either you, or your starter, or your engine, has a problem.
- The 216 and early 235 engine are not "splash oilers" - this is a splash oiler.
Re: Generator Circuit [Re: Frank50] #1311013 Fri May 17 2019 04:21 PM
Joined: Nov 2000
Posts: 1,601
F
Frank50 Offline OP
Shop Shark
Thanks all.


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