85 G/S Charging issue

Discussion in 'Airheads' started by Spark Plug, May 1, 2013.

  1. Spark Plug

    Spark Plug Low on compression

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    Help please. 85 R80 G/S. Gen light won't come on.

    Checked at the battery first. 11.8 at idle, 11.8 at 3K

    Found tests here...http://jhau.maliwi.de/mot/r-elec.html

    Checked Diode Board. Looks like crap (Black potting on the forward facing side is flaking off) Bench tested fine.

    Checked Rotor 3.7ohms.

    Checked stator no opens or grounds

    Jumped regulator and checked again 11.8


    Anyone have any ideas?
    #1
  2. Stagehand

    Stagehand Imperfectionist

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    gen light dead?

    under 12v isnt right anyway, and under 12v at 3krpm certainly isnt right either. The charging chain is broken, somewhere.

    back to hte first thing i said, try touching one of the D's to the stator housing with the key on. That should hotpatch the gen light, I think.


    Next problem I would look at is why the thing read under 12v at 3k rpm even with the regulator jumped. Without the regulator in place it should spike up to 15-16v at 3K.


    Also look at the brushes.

    Confirm you have a known good battery, as well.
    #2
  3. Mugwest

    Mugwest .

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    +1 on the panel bulb.

    And even if the bulb is continuous, i used to get a lot of schmutz on those dinky indicator terminals in that pod/panel from time to time. Would make the bulbs flaky or dead
    #3
  4. Spark Plug

    Spark Plug Low on compression

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    I'm charging the battery up right now. Problem is I'm at work so I'm limited on what I can do right now. Brushes are a possibility but would they go over night? Seems to me that they would be a little more intermittent. Bike operated fine yesterday.


    Does the light have to be working properly for the bike to charge?


    Whats the procedure for testing a/c output at the stator? I'm going to try this when I get home.
    #4
  5. Mugwest

    Mugwest .

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    Yep. I forgot the terminology but it's an exciter circuit thru the bulb or some such
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  6. Stagehand

    Stagehand Imperfectionist

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    Ah! Yes, the charge light in integral to charging. It should come on when the ignition is on, go out when starting, come on at idle, and go off at about 2K rpms or so. Its definitely needed for proper charging function, as it acts as a resistor on the circuit, with the added benefit that you can use it for diagnostic purposes. SOme people install a parallel resistor inline aroudn the lamp, which works great when the lamp blows, but then again, you cant tell if its not working by looking at it, like you cna with a lamp :D

    AC testing at the stator should be straightforward. It should be producing a buttload of AC voltage at the three-wire bundle on the stator. Its the diode board what rectifies it to DC.
    #6
  7. Mugwest

    Mugwest .

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    I like how this guy s'plains it:

    Without getting into too much confusing detail as to how it works, there’s basically a little bulb on your dash that says your bike is (not) charging (when illuminated). This bulb apparently provides light to a tiny magical gnome just below the light socket. When this light first comes on when you start your bike, it awakens him. He then summons the hamsters behind the front motor cover to begin spinning the wheels to charge your bike.

    Spot on!! :lol3
    #7
  8. Stagehand

    Stagehand Imperfectionist

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    oh yeah thats much better tha I what i was gonna say :clap:rofl
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  9. Spark Plug

    Spark Plug Low on compression

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    That was it, swapped the high beam bulb with the gen and presto..... were charging again.



    Thanks guys.:clap
    #9
  10. Mugwest

    Mugwest .

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    Excellent, Plug :thumb

    Now Teachable MomentTM Part 2: Can you see why it's A Very Good Thing to have a spare of that little magic gnome in your on-board spares kit? :nod
    #10
  11. Stagehand

    Stagehand Imperfectionist

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    Dont most people carry a spare in the high beam socket? :evil
    #11
  12. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    In my /5 (with warning lamps. etc in the headlight bucket) I carry spare lamps and fuses in a Ziploc Snack Bag perched between the nest of wires. So when I need to change a bulb or a fuse, spares are available.

    It's different in later models, but you get the idea.

    --Bill
    #12
  13. Spark Plug

    Spark Plug Low on compression

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    I've always wanted a gnome in my tool bag.



    Off to Ebay... :lol3
    #13