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Please Help! Polarity of generator on '52 Cadillac with 6-volt negative ground

Started by jdemerson, July 03, 2022, 02:10:58 PM

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jdemerson

Car: 1952 Cadillac 6219X with stock 6-volt negative-ground electrical system.  Battery is new; generator is rebuilt and is capable of charging; voltage regulator is new and American-made; contacts and grounds are checked and seem OK though perhaps I missed something.

Problem: When following the procedure in the manual to set the polarity of the generator to match negative ground, it seems to work and to be in charging mode when revved up (as indicated by 7.6 on volt meter). But then it appears to switch back to the wrong polarity and  then does not charge (voltage stays below 6.5). The red generator light is always on. Today I left point A with generator charging (as indicated by volt meter), and 12 miles later when I got to point B, it was not charging and the polarity of the generator appeared to be reversed as if for positive ground. All this even though the car had been running throughout the trip.

Help needed: I'm hardly an expert but I have read the service manual and searched this Message Board; my problem seems mysterious. Why would the polarity of the generator reverse to the wrong polarity (if indeed that is what the < 6.5 volt reading means)? And why does generator light always stay on? Does anyone have any experience with a problem like this?  Advice?  Thanks in advance.

John Emerson
1952 Cadillac 6219X
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

signart

Don't know if this helps, but you know that your generator does not charge until the engine reaches approximately 2000 rpm? In other words, it doesn't charge at idle.
Art D. Woody

jdemerson

Art,

Yes of course I do know that about generators (vs. alternators). But when the polarity is not set right, the generator can't charge at ANY rpm. It's as if it "thinks" the car electrical system is positive ground. And it's not...

Thanks!
John
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

jdemerson

I've done further research. I am baffled and still need help!  Thanks -- John
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

toybox

 Hi John, If your gen light is always on something is wrong. Are you sure about your connections?  Check continuity between your field wire at the regulator and the gen. It sounds like you may have crossed up your ground and field. I have never had to polarized a generator, only the regulator so I'm a little unsure about what you are doing there. 
                                                                   Best of luck, Tim

fishnjim

After you verify all the connections, wiring, and techniques are proper, if still persists;
These are strange units because early negative ground but still 6V, before 12V ('53).   
Most 6VDC autos are pos ground, so I'd check to make sure the generator was wound properly for negative ground and correct voltage regulator. 
The gen light staying on means it's getting juice to that circuit from gen. and apparently didn't go out during the charge so not functioning properly indicating connection issue.
Somewhere there's a curve of voltage vs rpm for these, and it's not linear as I recall.   Not much happening at <700.
There's an electrical diagram for these to troubleshoot, if you don't have one.https://www.opgi.com/books/electrical/full-color-factory-wiring-diagram6/wiring-diagram-1952-53-cadillac-11x17-color-ce16103.html
You should be able to tell if polarity has changed with a DVM clamped on, it should go negative or positive on VDC with same probe position. I doubt it's reversing, but just a guess.  I don't think it would charge at all if that was the case.  More likely a wrong or loose connection/bad ground somewhere.

Lexi

Quote from: jdemerson on July 05, 2022, 07:14:50 AMI've done further research. I am baffled and still need help!  Thanks -- John

More as an add on to your research which you may wish to look into further.
I have a couple of vintage 1950s GM technical manuals on starter motors, generators and voltage regulators. There is a ton of technical information here which goes beyond that of what is contained within the Shop Manual. While directed at those who rebuild these items, if you think these may help I could scan some of the relevant pages for you. They are very highly detailed and extremely technical. Much of it is lost on me. They go back to at least the 1940s so 6 volt is covered. They sort of appear to be a huge collection of stand alone technical bulletins. These manuals are: "DELCO-REMY Electrical Equipment Operation and Maintenance Handbook DR-324" (my copy is the 13th edition, 4th printing from 1958), plus the voluminous supplement to DR-324, identified as DR-324A, (2nd edition published in 1957). Tough to diagnose what is happening from here, but if it is possible to narrow down what may help let me know. Or you may want to check the net for these. They are so technical they may not help unless you have training in that field. Clay/Lexi

CadillacFanBob

Quote from: jdemerson on July 05, 2022, 07:14:50 AMI've done further research. I am baffled and still need help!  Thanks -- John
Quote from: jdemerson on July 05, 2022, 07:14:50 AMI've done further research. I am baffled and still need help!  Thanks -- John

John,

Please contact Frank in Lisle,IL. He may be able to walk you through this, you spoke with him earlier on your choke housing, he is a very knowledgeable person and would love to help you, he is listed in the membership directory, he owns "Dean Martin's 1953 Cadillac" that will jog the memory bank lol

Bob
Frankfort, Illinois

CadillacFanBob

Quote from: Lexi on July 05, 2022, 04:28:52 PMMore as an add on to your research which you may wish to look into further.
I have a couple of vintage 1950s GM technical manuals on starter motors, generators and voltage regulators. There is a ton of technical information here which goes beyond that of what is contained within the Shop Manual. While directed at those who rebuild these items, if you think these may help I could scan some of the relevant pages for you. They are very highly detailed and extremely technical. Much of it is lost on me. They go back to at least the 1940s so 6 volt is covered. They sort of appear to be a huge collection of stand alone technical bulletins. These manuals are: "DELCO-REMY Electrical Equipment Operation and Maintenance Handbook DR-324" (my copy is the 13th edition, 4th printing from 1958), plus the voluminous supplement to DR-324, identified as DR-324A, (2nd edition published in 1957). Tough to diagnose what is happening from here, but if it is possible to narrow down what may help let me know. Or you may want to check the net for these. They are so technical they may not help unless you have training in that field. Clay/Lexi

Clay,

I am a manual and tool junkie, I am in awe just reading your post, I would be like a kid in a candy store just looking at all your manuals, tools and then being able to flip pages or view them. I am very jealous of you "my man" keep you posts coming, and your a very helpful knowledgeable person also.

Bob
Frankfort, Illinois

Jeff Rosansky CLC #28373

Has it ever worked with the current regulator?
We had to replace the regulator on our 55 (I know it's 12v) but had an issue getting it to work after the replacement.
I went thru a couple replacements and finally contacted the company that made it and got it working. The manuals say you adjust the point gap, but the new unit you adjust the spring tension. When I did that it worked ok.
Jeff R
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

Lexi

Quote from: CadillacFanBob on Today at 04:57:08 PM
Clay,
I am a manual and tool junkie, I am in awe just reading your post, I would be like a kid in a candy store just looking at all your manuals, tools and then being able to flip pages or view them. I am very jealous of you "my man" keep you posts coming, and your a very helpful knowledgeable person also.
Bob

Bob thanks. I like helping out members with their Cadillac questions especially as I know how unsettling some of the issues can be, especially when "unobtainium" is involved. Like you I am also a manual and tool junkie, ((my shop looks like "light industry" as Dad used to say), and I hate not having at least the information to tell me what is wrong with my car and how to fix it. While I do most of my own repairs some jobs I leave to the professionals, but at least when I go to the shop I can intelligently discuss the job with the mechanic. I guess I am also a research and historical junkie which helps as a vintage car owner. Was fortunate to buy out a collection of vintage papers from a '50s Cadillac dealership. The business owner was also one of the first CLC members. I found another publication that would directly assist John's '52 Caddy charging issue. It is titled; "The Charging Circuit", and is the size of the previous 2 publications I noted except it is more booklet in length (only 24 pages). The copy I have is the revised edition from January 1st, 1959, and it does contain 6 volt system data. Aimed more at a 3 Stooges level, (not as technical), so good for me! See attached images. Also a quick "Facts to Remember" from the booklet. Clay/Lexi

jdemerson

#11
Quote from: Lexi on July 05, 2022, 04:28:52 PMMore as an add on to your research which you may wish to look into further.
I have a couple of vintage 1950s GM technical manuals on starter motors, generators and voltage regulators. There is a ton of technical information here which goes beyond that of what is contained within the Shop Manual. While directed at those who rebuild these items, if you think these may help I could scan some of the relevant pages for you. They are very highly detailed and extremely technical. Much of it is lost on me. They go back to at least the 1940s so 6 volt is covered. They sort of appear to be a huge collection of stand alone technical bulletins. These manuals are: "DELCO-REMY Electrical Equipment Operation and Maintenance Handbook DR-324" (my copy is the 13th edition, 4th printing from 1958), plus the voluminous supplement to DR-324, identified as DR-324A, (2nd edition published in 1957). Tough to diagnose what is happening from here, but if it is possible to narrow down what may help let me know. Or you may want to check the net for these. They are so technical they may not help unless you have training in that field. Clay/Lexi

Clay,
    Thanks for this posting and for your kind offer. I have a reprint of a thick Cadillac publication called "Cadillac Thorough-Check, 1949-1960". It has a detailed chapter on generator & VR tests, adjustments, repairs -- perhaps 8 pages or so in this area. I'm trying to figure out how to get to the "right" issue.
John
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

jdemerson

Quote from: Jeff Rose CLC #28373 on July 05, 2022, 06:37:45 PMHas it ever worked with the current regulator?
We had to replace the regulator on our 55 (I know it's 12v) but had an issue getting it to work after the replacement.
I went thru a couple replacements and finally contacted the company that made it and got it working. The manuals say you adjust the point gap, but the new unit you adjust the spring tension. When I did that it worked ok.
Jeff R
Thank you, Jeff. I have had the same problem with two VR's, with the current one being new and premium U.S.-made. So I suspect problem is not a faulty VR bu rather in wiring, grounds, etc.  I'll provide an update after I get it solved!
John
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

jdemerson

Quote from: toybox on July 05, 2022, 09:31:59 AMHi John, If your gen light is always on something is wrong. Are you sure about your connections?  Check continuity between your field wire at the regulator and the gen. It sounds like you may have crossed up your ground and field. I have never had to polarized a generator, only the regulator so I'm a little unsure about what you are doing there. 
                                                                  Best of luck, Tim

Thank you, Tim.  Yes, I am checking the wiring carefully with help from experts.  An interesting aside:  According to the Cadillac Service Manual, to properly polarize the generator, you connect the two posts on the voltage regulator. But it is the generator, not the regulator, that has polarity  being set by this flashing process.

John
John Emerson
Middlebury, Vermont
CLC member #26790
1952 Series 6219X
http://bit.ly/21AGnvn

Lexi

Quote from: jdemerson on July 06, 2022, 07:03:01 AMClay,
    Thanks for this posting and for your kind offer. I have a reprint of a thick Cadillac publication called "Cadillac Thorough-Check, 1949-1960". It has a detailed chapter on generator & VR tests, adjustments, repairs -- perhaps 8 pages or so in this area. I'm trying to figure out how to get to the "right" issue.
John

Hello John, I hear yeah. That is why at this point I am not sure what to copy and post for you. Sometimes these problems have us chase our "tail" until that eureka moment happens. I have that "Thoro-Check" publication and it is an excellent engine diagnostic manual for our cars.  Another handy reference book that one of your buddies may have is "Motor Auto Engines and Electrical Systems", (1973). Yes, this was published by the same group that did those automotive repair manuals (similar to Chiltons). Like the auto shop manuals this is a large sized hard back volume. Best of all this is just old enough to cover most of the electrical & charging systems for a great number of the cars that CLC Members chat about on this Forum. I bought the 5th edition in 1976 when new and it proved instrumental in assisting me when I had to rewire an old Coup de Ville that had burned up. Also, I will ask my buddy who owns a '52 Fleetwood to see if he has any suggestions for your situation. Keep us posted. Clay/Lexi

Lexi

Checked with my buddy whose '52 has been upgraded to 12 volt with lots of electrical changes, so no help there.  :'(  We met for the Plunkett Cadillac tour yesterday, (will do a separate post on that).  Clay/Lexi

jackworstell

jdemerson....interesting problem

Voltage dropping to less than 6.5V...my first guess would be the system stopped charging
    ( e.g. maybe cut-out relay opened when it shouldn't have) as opposed to polarity
    being suddenly and mysteriously reversed. Why do you think polarity switched ?  Because of drop to
    less than  6.5V ?
I take it that you are trouble shooting using a voltmeter only and no ammeter ?

The biggest mystery to me is the GEN light staying on even when charging.  But if no ammeter
    how can you be certain of charge/no charge ?  For example if you are measuring volts at the
    GEN terminal of the VR...it may show OK volts even if no charging to battery because of
      incorrect VR cut out relay setting
When you measure volts ...where do you take the measurement ?

I think the cut-out relay CLOSED setting on these cars is approx 6.8 V.  If you want I'll check
      my DR manual to be sure but I think you have manuals that show this

I take it you polarized the system by briefly jumpering between the BAT and FD terminals of the VR ?
      Did you get a brief spark ?

Two suggestions
      1) put an ammeter (say 0-30 amps) in series in the heavy wire going from the generator to the VR GEN terminal
      2) Check the VR cut out relay CLOSED setting ( probably need a helper}

Jack Worstell
7/9/22   NOTE two edits....both times changed BAT to GEN