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1972 Eldorado Generator light question

Discussion in 'Loop & Tonti' started by iosteyee, Sep 3, 2020.

  1. iosteyee

    iosteyee Just got it firing!

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    Hello Gents,
    I have had the Eldo for a number of years, but I'm new to this forum. I've had a number of older bikes over the years, this being my first Guzzi. I'm 52, live in Keene,NY up here in the Adirondack's, but haven't been riding a lot the last few years. Life has had the Eldorado parked for a few years. It had a charging issue when I put it away. Now, three years later I replaced the regulator hoping that was the fault. I started the bike and the Gen light went off which was a good sign as it had been on all the time prior to this. As the idle came down during warming up the light would come back on with low RPM's, this gives me hope that I've found my charging issue.
    Here's my question: After I shut the bike off, the Generator light stayed on. Is that, at all, normal? I didn't think it was, so I disconnected the negative lead to the battery. When I reconnected it the light stayed off. Any thoughts would be very welcomed and appreciated.

    Ian
     
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    What did you use for a voltage regulator? I've found the ones for an old 12 volt VW beetle from the 60s works best. It is identical to the one Guzzi used on the Eldorado's with the Bosch generator. Also when you put the new regulator in did you polarize it?
     
  3. iosteyee

    iosteyee Just got it firing!

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    John,
    I bought a Bosch regulator from an online source. I simply replaced the old one and put the spade connectors on the same connections. The only thing I did differently was to add a ground wire as there was not previously a ground wire going from the mounting bolts to the frame. I'm not sure what mean by polorizing?
     
  4. Kevin.NZ

    Kevin.NZ Cruisin' Guzzisti

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    Below are two link on how to polarize the generator from the genny itself and from the regulator. its to make sure the magnets in the genny are North/ South and not South/North. When you replaced the regulator you may have inadvertently "flashed" a contact, anyway if you do it you eliminate that as a problem.

     
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  5. Amboman

    Amboman Cruisin' Guzzisti

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    Last edited: Sep 5, 2020
  6. iosteyee

    iosteyee Just got it firing!

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    I'm still not sure how to polarize the Generator from the Regulator. Which two terminals on this attached pic am I supposed to connect?
    The Generator light goes off with the bike running. As it ides down the light comes on, so thats working. I still have a charging issue though, with the bike running my multi meter showed no increase in voltage as it was revved.
     

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  7. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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  8. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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  9. Moto-Uno

    Moto-Uno Cruisin' Guzzisti

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    Make a jumper cable that can reach from your battery positive lead to the generator ,
    Attach one end to the battery positive and momentarily touch the D+ lead on the generator with the other end of the jumper
    Done , leave the regulator alone , you've performed the arduous task of polarizing your Generator.
    Peter
     
  10. Kevin.NZ

    Kevin.NZ Cruisin' Guzzisti

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    Moto-Uno, you touch the battery + wire onto the "F" terminal which is the field winding. Not the "D" terminal as that goes to the commutator.
     
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  11. iosteyee

    iosteyee Just got it firing!

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    OK, Here's what I know about the bike now. New battery that has started the bike a couple of times, and sat on a tender overnight. Battery connected but bike switched off 13.07 V
    Low Idle 12.74 V
    High Idle 12.74 V
    So, it doesn't seem to be charging. I tried an earlier suggestion and touched Batt + to D+ on Regulator, so that may not have donw anything. So, now I should try Batt+ to F terminal on Generator? Is the "F" terminal labeled "DF"?
    Thanks for all the "newb" help. I'm thankful you're all willing to sink to my level.
     
  12. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Yes, you need to flash the field of the generator. Also possible that even in new, the voltage regulator could be suspect. When charging, (you may need to get to 2K RPM) you should get close to 14 volts at the battery.
     
  13. iosteyee

    iosteyee Just got it firing!

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    Thanks John, I'll touch a wire from the battery+ to the "DF" terminal on the Generator. Then I will run to 2000rpm and see how many volts are on the battery.
     
  14. iosteyee

    iosteyee Just got it firing!

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    OK, with battery connected and key off, I touched a wire from the DF terminal on the generator, to the +battery terminal. Bike still is not charging. What, other, tests with the multi meter might I try to determine the fault? Thanks in advance.
     
  15. Moto-Uno

    Moto-Uno Cruisin' Guzzisti

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    Kevin NZ , So I've polarized literally dozens of HD generators and they are all Batt +ve to the "A" terminal
    on the generator . Are the Bosch generators different ? I'll have to look around to see if I can find the motor
    test for generators that are off the bike . If it wouldn't pass the motor test all else was a waste of time . Peter
     
  16. Moto-Uno

    Moto-Uno Cruisin' Guzzisti

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  17. Moto-Uno

    Moto-Uno Cruisin' Guzzisti

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    The above shows what I did . This is similar to all generator Harley's ( I know were talking Guzzi) . Yes the field winding's are
    polarized , but it how it's done that I was describing . The HD Sportsters of the 60's also used Bosch regulators ( VW comes to
    mind) and were polarized in the same way . I believe you will find that the armature and field winding's have a common connection
    inside . Not to forget that the purpose of polarizing is to get the electrical flow in the proper direction for battery charging . Hope
    this kinda clears up the confusion . :) . Peter
     
  18. Tonerjockey

    Tonerjockey High Miler GT Contributor

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    Fun with electrons!
    re the lite on, ign switch off.
    Here's a cartoon of what's happening: (wire colors are for illustration purposes only. Your harness will be different colors)
    Eldo Gen Lite.JPG


    When the ign is on, 12V appears at the Gen lite (in green here) via the "hot" wires in red in this drawing.
    When the engine isn't running ( & ign on) the output of the generator is less than 12V, Current flows from the red wire, thru the Gen Lite, towards the generator (and regulator) via the purple line.
    When the engine runs and the generator puts out 12V (or more) the purple wire now has the same voltage level as does the red wire. Current flow stops thru the ign lite.
    If you have the ign switched off and the lite goes on, current must be flowing thru the lite assy, one way or the other (DC). Either the current lighting the bulb is coming via the red line or the purple. Also, there must be a path to ground for the current.

    Does your ign switch have an auxillary position? (One stop counterclockwise from the ign off position) Possible creative wiring could cause this lite to go on in Aux. I've left my Eldo with the switch in this position... not recommended.

    Possible your grounding of the regulator makes the system unhappy.

    Good luck,

    Alex
     
  19. Kevin.NZ

    Kevin.NZ Cruisin' Guzzisti

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    Well that's certainly confused me (very easy), I thought "A" was for armature or where you could insert an ammeter. Hope Isostyee gets it sorted.
     
  20. iosteyee

    iosteyee Just got it firing!

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    Thanks Alex, and yes Kevin, I'm a little disoriented too. Well, the thoughts of an easy fix are fading away. A yes, Alex, there seems to have been some creative wiring in the Eldorado. I'll try to find the right wiring diagram, but there seems to be a few possible for this year, and some modification to sort out too. Here's what it looks like just Cobbled 1.jpeg Cobbled 2.jpeg on the surface.
     

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