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365 GT 2+2 Electrical Question

Discussion in 'Technical Q&A' started by TheMac, Jul 17, 2010.

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  1. TheMac

    TheMac Formula Junior

    Sep 5, 2009
    452
    Alberta
    Full Name:
    Jon Mac
    #1 TheMac, Jul 17, 2010
    Asking on behalf of my father, whose 365 GT 2+2 will not charge, though the alternator seems good. He says that the wires from the alternator run to a small canister, maybe 2" long by 1" diameter. The canister is labeled Voxson (so something to do with the stereo? A noise suppressor?), and it appears fried, burnt, shorted out.

    First question, can he just bypass this burnt out canister (whatever it is) and reconnect the alternator so the battery will charge?
    Second question, what is this canister?

    Apologies for the lack of pictures; I am not present at the car's location. He made it to a car show okay, but now cannot start the car, so any assistance is appreciated. I have not been able to find good, detailed photographs of the 365 engine bay online, but he tells me this is the first thing connected to the alternator, on the left side of the engine bay, engine side of the radiator, between the alternator and the left fender.
     
  2. 12659

    12659 Formula Junior

    Oct 6, 2005
    349
    Seattle WA. USA
    Full Name:
    mark
    #2 12659, Jul 17, 2010
    There are 2 very high amperage fuses in that box. Chances are one of them failed. They are available at any auto parts store. Just check the continuity.
     
  3. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #3 Paul_308, Jul 17, 2010
    Last edited: Jul 17, 2010
    You didn't mention the year of the 365. There are wiring diagrams for 3 different 365 cars in my drawing package (http://www.FerrariWiring.com). Checking the alternator circuitry on each of these I learn that...

    All have a separate voltage regulator which has a black ground wire, a brown wire to the fuse panel and a wire to the alternator (color varies). The Voxson canister could be the regulator.

    The alternator also is wired to the battery through a shunt for the dashboard ammeter...this could also be the Voxson canister. The shunt connects the alternator to the battery to monitor current through it. All electrical devices needing +12v power except the starter, are wired to the shunt so their current can be monitored.

    Shunts rarely fail while regulators often go south as the regulator has active devices (diodes) and the shunt is really a calibrated resistor, but like everything else electrical, it can and will fail at an inopportune moment.

    I'm sure you know the alternator can be ok yet the external regulator can be bad. Best to learn what is what by how it's connected...hope these clues were helpful.

    __________________________
    http://www.FerrariDiagrams.com
     
  4. TheMac

    TheMac Formula Junior

    Sep 5, 2009
    452
    Alberta
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    Jon Mac
    #4 TheMac, Jul 18, 2010
    Thanks both to 12659 and Paul. I am trying to get pictures of the unit. It actually sounds more like the shunt to me than the voltage regulator, and it sounds like it is indeed cooked itself.

    The car is a 1970 365 GT 2+2. Consulting your site's wiring diagrams, it looks like the dual dizzy GTC4 would probably be the closest thing, but it's still a mystery to me until I actually see the unit in pictures. When I get pictures, I will post. Thanks again to those who shared their expertise.
     
  5. TLKIZER660

    TLKIZER660 Formula Junior

    Jul 30, 2004
    315
    Québec
    #5 TLKIZER660, Jul 18, 2010
    It sounds like the 3 microfarad capacitor that is in the same location on my 365 GT 2+2 (Italian version). It also has a Voxson radio although I don't see anything on the capacitor except the words 3 microfarad stamped on the end.

    I just fried mine also (along with the alternator and the wires adjacent to the alternator) so I have to figure out what to do as well. I suspect that it can be bypassed at the risk of radio noise but don't take my word for it. It doesn't show up on my schematic, since radios were dealer-installed in Italy.

    I'm going to follow your thread closely.

    Tom Kizer
     
  6. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #6 Paul_308, Jul 18, 2010
    Voxson was a primarily a manufacturer of radios and if it's stamped 3µf it's definitely a capacitor. Replacements are available at Radio Shack or anywhere car stereos are installed. It has no bearing or function in the alternator circuit and can be removed and ignored for now.

    Again, I'd suggest learning where the shunt and regulator are located in the car, then doing a voltmeter test of each. I.e. the shunt should have battery voltage on all wires going to it. Regulator should be getting battery voltage on the brown wire through fuse #3 left fuse box, which provides exciting voltage from the key switch 'run' position.


    _______________________
    http://www.FerrariWiring.com
     
  7. TheMac

    TheMac Formula Junior

    Sep 5, 2009
    452
    Alberta
    Full Name:
    Jon Mac
    #7 TheMac, Jul 19, 2010
    Last edited by a moderator: Sep 7, 2017
    Thanks again for the assistance, Paul and Tom. So we now know that it is the capacitor, and it is fried. It seems like this is a problem, but not THE problem. Did it just fry because it's old and failed or whatever, or maybe there's a voltage regulator problem. Apparently, Dad wired the leads to a 15 amp fuse and it blew in a second, so I think just replacing the capacitor is not the solution yet. I am sure he will run down the problem, and I will post again when I have an update.
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