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Thread: well, the darn thing is out

  1. #791
    Super Moderator LarrBeard's Avatar
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    Looking at several places, a charge voltage of about 7.5 volts is just about right for a three-cell battery (6-volts). Many older charging systems were set to 7.8 volts. Now, if I take that number for a three-cell battery and multiply times 4 for a 12-cell 24-volt system, anything under 31.2 volts would be an acceptable charge level.

    Anything under 28.4-volts is getting on the low side.

  2. #792
    Senior Member pelago's Avatar
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    it is reading 34 vdc, nothing gets hot, but just too much, when i release the disconnect relay by pushing down on the voltage realy the disconnect disconnects and it goes to 29 volts as soon as i release the voltage relay the disconnect goes back into play and it goes to 34 volts


    regulator page 142.jpg

    when i break the contacts on the center relay the reg relay on far right breaks contact and voltage rests at 29 with a nominal + but a good charge voltage, have no idea what why this happens, but when the last relay on right activates it puts a considerable load on motor
    Last edited by pelago; 08-06-2018 at 12:57 PM.

  3. #793
    Senior Member pelago's Avatar
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    you know this thing here turning into a book? 77k looked at it, damn

  4. #794
    Super Moderator LarrBeard's Avatar
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    That's because it's a good story and we're answering questions people want to know the answers to. Here is some info about that regulator:

    Ira – and all who read this. Corrections are welcomed since a lot of this is from just reading and looking. I could be full of … whatever … on some of this.

    The generator in the M38A1 is what is called a type A generator. It has its field coils isolated from the armature internally. One end of the field coils is grounded, the other comes out to the field contact in the generator connector.

    Look at the two figures I have attached to this note.

    The first is the internal wiring diagram of what I think is the regulator for the M38A1. There are so many variations running around there may be some differences, but I hope I’m using the right diagram.

    The second diagram is what I’ve come up with after a week of studying old stuff. I’ve drawn it to look like relays and switches because that’s what you and I recognize.

    On the left, S1 is the cutout relay contacts. This is the left relay in the box and when the generator stops producing a voltage, it disconnects the battery from the generator (the ARMATURE connection). Since the engine is running and the generator is charging the battery this switch is closed.

    Now, we have two sets of relay contacts and one (and only one) resistor controlling the generator.

    In the condition have drawn the circuit, this represents the condition at start-up. The full battery voltage is being connected across the field coils through S2,S3 and K3B and the system is charging pretty hard.

    K2 is the middle relay, the over current relay, that controls S2. Until the current provided by the generator exceeds the safe rating for the brushes and windings, that relay will not energize and S2 stays closed. If you open those contacts manually, (which you say you have done) you switch R3 into the field circuit. That reduces the field current – which in turn lowers the output voltage of the generator.

    Now, K3A is the voltage sensing coil for the voltage regulator relay. As long as S3, (the contacts on the voltage regulator relay) stays closed, the current set by S2’s condition will flow in the field coil. I cannot find any information on just what K3B does, but it is a current coil in series with the field.

    Here is what I suspect happens. Current flowing through K3B keeps S3 closed under normal conditions. K3A, the voltage coil for K3, is connected to the BATT/ARM through resistor R2. If Armature (and battery) voltage gets to the regulator set point, current through K3A opposes the magnetic field set up by K3B and opens S3. Field current is now set by the series combination of R1 and R2, which lowers field current – reducing output voltage – allowing S3 to close again and the cycle continues.

    S3 only opens a very few thousandths of an inch, and will open and close a couple of hundred times a second as the battery approaches full charge.

    Since charge cutout voltage is high, the springs that hold the points closed are exerting too much tension. The cutout point can be changed by adjusting the nut on the voltage regulator armature - its movable coil. The photo shows the spring adjustment on a civilian regulator out of the '48 junk pile.

    Another guess. When you manually open the contacts on the center relay (the over current relay), you remove most of the current through K3B. That leaves K3A as the controlling coil for S3. Since K3A will have voltage on it, and K3B can’t override it, K3A opens S3 when S2 is opened.

    With S2 and S3 open, there is still some field current through R1 and R2.

    Just to finish the story, R4 is there to absorb energy dumped when the magnetic field in the field coils collapses as S2 and S3 open and close. As the field collapses, a negative transient is generated. Even civilian regulators use this resistor to protect the points on the relays from arcing too badly. Since the M38 has a bunch of radios, which DO NOT like negative transients, the rectifier (also commonly called a transient suppresion diode) clamps negative spikes at the field terminal.

    And, to answer the last point. With the last relay on the right activated, the center relay activated and the left relay activated, the generator is charging the battery at its highest possible charge rate. Yep, that’s a considerable load on the engine.

    GUYS –If this isn’t right – correct me!
    Attached Images Attached Images
    Last edited by LarrBeard; 08-07-2018 at 06:07 PM.

  5. #795
    Senior Member pelago's Avatar
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    was measuring voltage and making notes of what was where, and i accidently activated the cut off relay and damn the generator started up like a motor. wow, but took me few seconds to get dc disconnected and had a whisp of smoke from regulator, going to have to look under neath and make sure nothing got crispy

  6. #796
    Super Moderator gmwillys's Avatar
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    LarrBeard, excellent work on your research. I can say that I've learned a lot about the voltage regulator from your work.

    Pelago, your body of work on your project is an inspiration to the rest of us to get out and make our restorations happen. I look forward to seeing your daily progress. Now, I need life to slow up a bit to get after my own project.

  7. #797
    Senior Member pelago's Avatar
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    letting voltage regulator cool a bit, got to do some thinking on that. lot of great information but need to digest it a bit. now this damned steering rod and the tube driving me nutssteering outer shaft.jpgupper steering race bearing.jpg
    i have already destroyed one of these and have the original one, cleaned up and lubricated (considerably more substantial than the new one) and then have the new one from Kaiser. HOW IN THE SAM HELL DO YOU GET THAT DAMNED RACE BEARING INSIDE THE TUBE FROM THE TOP

  8. #798
    Super Moderator gmwillys's Avatar
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    Kaiser Willys has a video showing the bearing sliding into place. I would take an inside caliper and measure the column tube to ensure that the tube is in fact round, then compare the bearing outside diameter with the inside diameter of the tube. Compare the original bearing with the reproduction bearing. Something is out of whack for you to not be able to get the bearing to seat within the tube. If you will, take some pictures of what you are seeing, then maybe one of us will see something that is amiss.

    https://www.youtube.com/watch?v=NsILb3-O4AY

  9. #799
    Super Moderator LarrBeard's Avatar
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    Voltage regulator is probably OK. Go do something else for a while and we'll figure out how to reset the over-voltage relay when we need to. You've got enough battery to start it every so often to keep it in the habit of running.

  10. #800
    Senior Member pelago's Avatar
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    I AM (EVERY ADJECTIVE IN THE WORLD TO EMPHASIZE STUPID) STUPID All the diagrams i had suggest that the upper race bearing is inserted with the shaft hole DOWN, and that is how i have been trying to do this, not having a whole steering assembly that was not destroyed i did not take one apart, all this time i had been trying to put the GD thing in uspside down. stupid stupid stupid

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