1952 AC Delco Generator

[MercMontMars]

Hi there, I’m working on an early 50’s AC Delco 6v generator. I’m trying to test the unit to see where it’s at functionality-wise which I’m sure is bad but it is clean and seems worth trying to fix up. The two terminals are marked, one being F and the other A. I’ve never worked on these, what do these stand for? Once I know that, how might I go about testing it? I’ve watched a couple videos on the topic but I’m not confident enough to know I won’t fry the unit.

 

 

 

Thanks for any help!

Edited July 29, 2023 by MercMontMars (see edit history)

[JFranklin]

F= Field  A= Armature

[Fordy]

Join F and A with a short piece of wire. Connect the case to ground (- if negative earth) and the 2 you have linked to the live terminal (+) If the generator is not damaged internally it will run as a motor. You will also probably need to inspect the commutator for wear (that's the copper segments the brushes run on). If its badly damaged scratched up, you need to make a very light cut on a lathe to smooth it out. After that is done use a fine blade between the segments to cut away the mica to a depth of a few thou. For 6V use a good ohm meter to measure the field resistance - it should be around 3 ohms.

Generally, these are bullet proof and will only need new brushes and possibly the commutator skim. Whilst you are there you might as well do the bearings too since they are so cheap.

[Frank DuVal]

For a GM type "A" circuit or Ford type "B" circuit? They are different tests!

 

For either, ground the case (doesn't matter if positive or negative ground for this test) and hook the hot to A. Now for "A" circuit types ground the F terminal. For "B" circuit types hook the F to hot.

 

I think I have this right.... 

[Fordy]

8 hours ago, Frank DuVal said:

For a GM type "A" circuit or Ford type "B" circuit? They are different tests!

 

For either, ground the case (doesn't matter if positive or negative ground for this test) and hook the hot to A. Now for "A" circuit types ground the F terminal. For "B" circuit types hook the F to hot.

 

I think I have this right.... 

Either way same result with F and A being connected to the same battery post - same tests just walking a different path doing it. Yes the generator may "flash the poles" so it thinks it is on a different grounding system but easily sorted.

Edited July 30, 2023 by Fordy (see edit history)

[Frank DuVal]

2 hours ago, Fordy said:

Either way same result with F and A being connected to the same battery post - same tests just walking a different path doing it.

You missed what I was saying!

 

The "A" circuit field connection needs to be grounded to operate! The field is internally connected to the A terminal with the other end of the field winding.  The "B" circuit field connection needs to be connected to Hot to work. The field coils are connected to ground (case) internally.

 

See this Delco training manual, it explains the difference in "A" and "B" circuit generators:

 

www.delcoremyhistory.com/images/Training%20Manuals/Training%20Chart%20Generators%202.pdf

 

If you tie an "A" circuit F terminal to hot, then the field has no current flowing, so no magnetic field.

[37_Roadmaster_C]

@Fordy,  GM generators have the field internally connected to the A post and supply a ground to the F terminal to apply full field. Frank is 100% right about the differences in Ford and GM.  As for "Motoring" a generator for a quick test, I do not know if the field is needed, but if it is, the F terminal will need to be grounded on a GM generator. In any case, no harm will be done if connected wrong for a Motor test, it just may not work as expected.

[Fordy]

This diagram is from the manual referred. Now I may just be a dumb ass electrician but both circiuts are the same apart from sequence of the field and regulator. (ignore the blue line in "B" to earth - it may as well have the same ground symbol as the "A". They are both series connected so order should not matter. Now I am completely confused!!

[Bloo]

The sequence is the only difference. In function it does not matter, but now take the regulator away and let the blue wire from the field coil hang open. In the first diagram you would have to connect the blue wire to ground to make the generator charge. In the second diagram you would have to connect the blue wire to battery voltage to make the generator charge.

[Fordy]

Thanks Bloo. Sometimes having a formal qualification in something just means you fail to see the obvious. Either that or retirement and not exercising the skill set has corroded those neural pathways.

[dodge28]

I would gladly replace that generator with a 10 SI Delco.

[Frank DuVal]

The difference is the internal connection of the field coils.

[John348]

When testing, for a 6V power source I would suggest using a battery charger they over current protection, if there is a internal dead short using a battery direct could become real ugly real fast 

[MercMontMars]

@Frank DuVal

 

Thanks for the heads up, I had no idea! It is a GM Generator out of a Pontiac Chieftain. Which diagram is for the GM generator? Thanks again.

[Frank DuVal]

The "A" circuit.