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Magneti marelli generator GCA 113

Discussion in 'Vintage (thru 365 GTC4)' started by jc larrieu, Jul 13, 2019.

  1. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
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    Full Name:
    Jean Claude Larrieu
    Hi from France
    My generator gives an erratic charge ; I have taken it off my car ( Daytona 1974 US version ) and tested it by 2 different shops ; one said it is OK , the other say it is very low powering !!! I try to find the regulator , but I cannot identify it from all the relays , Is it in another place than the relay pannel located under the fuses boxes ? I have an electric diagramm on the user manual but it seems not correct for the US version .
    Thanks for your help .
     
  2. TTR

    TTR Formula 3
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    Timo
    #2 TTR, Jul 13, 2019
    Last edited: Jul 13, 2019
    365 GTB/4 voltage regulator is usually located under the dash, above the pedals, left of steering column (Sorry, I don’t have a picture on hand at the moment).

    As for the wiring diagram, all four factory issued ones I have are far from accurate or complete, so I recommend caution if/when using any of them for reference.

    Erratic charging could be caused by loose or oxidized electrical wiring contacts, including grounding. I would start by cleaning & tightening all related connectors & wire ends.
     
  3. TTR

    TTR Formula 3
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    Here’s couple of different voltage regulators found in 365 GTB/4s, both in U.S. delivery examples currently in my care.
    First (Red with 3 terminals, externally grounded) I believe is an OEM unit in a late production car, second (Silver with 2 terminals, internally grounded) is an aftermarket replacement unit (by MM) in mid production car.

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  4. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
    6
    FRANCE
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    Jean Claude Larrieu
    Thank you very much to both o you ; I shall dive under the dashboard and try to find the regulator ; I have investigate further on the generator ; it seems some negative diodes are in short circuit . In France , very hard to find a good shop for repairing this ; too olde they say !
    Thanks again .
     
  5. turbo-joe

    turbo-joe F1 Veteran
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    romano schwabel
    those diodes you may change by yourself. have a look on the old ones to identify and then google a little
    where in france you are located? may be you will copme around and I could help? I´m located near basel/switzerland but on the german side
     
  6. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
    6
    FRANCE
    Full Name:
    Jean Claude Larrieu
    Thank you ; the photos from TTR help me to find the regulator which is not an original Marelli one but an aftermarket one . My car is fitted with electric power steering ( super feeling with the steering ) and the regulator was at the right place but hidden by the mitsubishi electronic box which manage the steering . Turbo joe , thank you for your offer to help me , but we are really at the opposite side of France ; I live close to the Manche coast , face to GB , north of Dieppe harbour . I' ll try to find an electrician who is not frightened when seeing the alternator , as the one I met last week , a young chap saying what an old device you have here ! I have opened the alternator and I must confess I have been a little bit confused by what I see inside and I am not able to do the job ; give me an engine to work on , OK , but the alternator , no way . Thanks again Folks .
     
  7. turbo-joe

    turbo-joe F1 Veteran
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    post some photos from the dismanteled alternator please. the diodes you can check easy with an ohm-meter
     
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  8. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
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    FRANCE
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    Jean Claude Larrieu
    I have checked the diodes as explained in the Ferrari repair book , ohmeter between positive and negative born and the diodes holder . The positive diode is shortcircuited . I have phone to some " specialist" in France who are supposed to be able to repair even the old alternator IF they find the parts ( the diodes ) . Any diode source you should know ?
     
  9. turbo-joe

    turbo-joe F1 Veteran
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  10. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
    6
    FRANCE
    Full Name:
    Jean Claude Larrieu
    Thank you , I am still investigating the origin of the trouble . It is sure some diodes are failing ; but , one guy told me the stator was not very well ; another tells it is OK ! He wabts to check it without the diodes support plate . That' s my next step . Mfg
     
  11. jc larrieu

    jc larrieu Rookie

    Jan 30, 2015
    6
    FRANCE
    Full Name:
    Jean Claude Larrieu
    I brought the stator to an electric motor rewiring shop who checked it at 1000 V ; the stator is OK .Some isolant varnish was put on it , cost : 20 € tip . Bring the stator to the automotive electrician ( a very small shop like 50 years ago ) . Verdict , 2 Diodes are out ; I told the guy to change the 6 . Resoldering of some wires , reassembly , test : Charging is OK . Cost : 20 € for the shop work , plus 40 € tip for the worker . I put the generator back on the car yesterday ; it works fine . I have now to test it on the road .In the US , one firm charge 2000$ for repairing the alternator
     
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  12. turbo-joe

    turbo-joe F1 Veteran
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    romano schwabel
    good to hear/read all ok again for little money :)
     

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