Starter and Alternator
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  1. #1
    Real cars have hydraulics DoubleChevron's Avatar
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    Default Starter and Alternator

    Hi Guys,

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    I've going to give the really grotty looking starter and alternator a
    quick going over.

    I've whipped the regulator off the alternator and found the brushes
    all but worn away (the back brush being *FAR* more worn --strange).
    I've removed the rectifier board. I can't figure how to test the
    [email protected] though. It looks like it uses a pair of diodes on each phase,
    however my multimeter will not give me a reading on them ... They
    appear to be open circuit ... Which of course isn't possible. Any
    ideas ??

    The starter ?? It's tiny, and has a bulge at the end of it, I thought
    "Hmm, must be a geared reduction starter, I've never seen on of them
    before". I whipped the end off it .... Bloody brilliant, what a
    fantastically made starter. sealed proper roller bearings, sealed rotor
    (no corrosion on it's windings), 4, yes four brushes in this little
    baby ... And a geared reduction unit at the end.

    I don't know if it left the factory with this starter ... But man I
    want more of 'em :-)

    seeya,
    Shane L.
    'Cit' homepage:
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    '85 Series II CX2500 GTi Turbo I
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    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


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  2. #2
    Contented Peugeot Driver addo's Avatar
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    If you unsolder one end of each diode, knock up a quick circuit with a 9V battery, LED and a couple of electronic-size jumper leads with alligator clips. Get the LED working solo with the 9V battery, then plumb the suspect diode into the circuit. It will work only one way around. If neither - it's stuffed.

    When you do get it hooked in and the LED glowing, measure the V across the alternator diode. You should find them pretty consistent (I'd be happy with 10% fluctuation). It's a bit of a fiddle, and the kind of thing that drove me to buy a new meter with diode and tranny testing.

    Hoard a spare old starter in good nick. Many automotive sparkies don't do proper undercutting anymore, and a rebuilt won't last well.

    Cheers, Adam.

  3. #3
    Fellow Frogger! Decca's Avatar
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    Double C
    Diodes can go open circuit/ high resistance
    As Addo said you may have to unsolder one leg to prevent the meter reading through other components
    Your multimeter ( on ohms/ resistance setting) should show a diode conducting one way and blocking the other. Most multimeters have a diode test function which will give no reading one way and the other way will show the voltage drop across the diode . voltage drop should be .5 to .7volts thereabouts.
    Test your meter by shorting testleads together. should read nearly zero, bearing in mind testleads have a alittle bit of resistance in them.

    May have to make sure the testleads make good contact onto the diodes as build up of grot will prevent good electrical contact.


    Decca
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  4. #4
    twm
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    Quote Originally Posted by Decca
    Double C
    Diodes can go open circuit/ high resistance
    As Addo said you may have to unsolder one leg to prevent the meter reading through other components
    Your multimeter ( on ohms/ resistance setting) should show a diode conducting one way and blocking the other. Most multimeters have a diode test function which will give no reading one way and the other way will show the voltage drop across the diode . voltage drop should be .5 to .7volts thereabouts.
    Test your meter by shorting testleads together. should read nearly zero, bearing in mind testleads have a alittle bit of resistance in them.

    May have to make sure the testleads make good contact onto the diodes as build up of grot will prevent good electrical contact.


    Decca
    The trick with brushes too is that if you cant get the right size get something oversize and if you are gentle you can file them down to size very easily they are only carbon.

    Cheers

  5. #5
    Real cars have hydraulics DoubleChevron's Avatar
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    Thanks Guys,

    I had two identical alternators here. One has the nice big diodes in the rectifiers I'm used to and the one I had trouble with looked like it had a pair of diodes on each phase.

    I ended up testing and re-soldering the diodes on the rectifier with the single big diodes.

    I managed to get some replacement brushes for the regulator at the local auto-electricians. I NEVER intend replacing those brushes again unless I have no other choice. I had to fight against the brush springs using a pair or long fine tweesers to feed the brush wire up through the brush housing to be soldered at the top.

    I tried to bench test it without much sucess. I hooked up a battery to the '+' output on the alternator and hit the exiciter wire to the battery '+' while spinning the alternator with my drill. Hmm.... Only 12volts .... no more.

    I decided I must be spinning the alternator to slowly. So I hooked up a globe in the exciter line (just like the altnerator light on the dash). The light lit brightly until I span the alternator at which time it extinguished. So the alternator is working, but not spinning fast enough to generator more than 12volts.

    It's on to the driveshafts and clutch now While I'm there I'll look at the cooling fans too. One of them is noisy.

    seeya,
    Shane L.
    Attached Thumbnails Attached Thumbnails Starter and Alternator-regulator.jpg  
    'Cit' homepage:
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    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  6. #6
    Contented Peugeot Driver addo's Avatar
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    Are you sure it's all working OK? Output should be over 13V provided the speed's up.

    A deficient alternator is a real pain - for example, every single "clogged injectors" case I've seen has been (in fact) an alternator problem. Usually after the owner's paid $300 for 6 injector service.

    Cheers, Adam.

  7. #7
    Real cars have hydraulics DoubleChevron's Avatar
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    Yeah the drill is one of those cheap heavy duty hammer drills with a geared reduction. It doesn't spin the alternator very fast and I'm only spinning it by the fan nut with a socket.

    The fact the idiot light goes out tells me it's ok. I probabably should rig up a big pulley to drive from the drill .... That would spin it fast enough.

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

  8. #8
    Fellow Frogger! Decca's Avatar
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    Could be a speed problem Double C

    Alternators need to to spun fast hence they had small pulleys compared to the old generators


    Decca
    Present --2016 2008Outdoor / 2014 RAV4 Diesel (My utilitarian beast, now with A/T tyres...)

    Past -- 19?? 403 / 1974 504GL / 1972 R12TL / 1995 405SRi / 1997 406ST / 1998 306XT / 2004 406HD1 / 2008 308XSE HDi / 2008 307XSE

  9. #9
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    Shane, AFAIK the alternator light goes out once there is little enough voltage to light the lamp in comparison to the battery voltage; ie. potential difference. So, the light will go out once the alternator is putting out anything above approximately 9V and will re-light if it puts out above about 15V, so it's not a great test. I'd still suggest that it's probably OK though, because you don't usually get only one or two volts drop with an alternator problem - it's usually a big drop in volts or no charge at all. Probably just not spinning fast enough.

    Stuey


    2003 PEUGEOT 206 GTi

  10. #10
    1000+ Posts robmac's Avatar
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    Default alternator light

    Quote Originally Posted by Stuey
    Shane, AFAIK the alternator light goes out once there is little enough voltage to light the lamp in comparison to the battery voltage; ie. potential difference. So, the light will go out once the alternator is putting out anything above approximately 9V and will re-light if it puts out above about 15V, so it's not a great test. I'd still suggest that it's probably OK though, because you don't usually get only one or two volts drop with an alternator problem - it's usually a big drop in volts or no charge at all. Probably just not spinning fast enough.

    Stuey

    Actually the "alternator light" is usually arranged as an indicator of when the star point in the alternator field is not at zero, ie the field has been "excited" and unit is charging.

    As you say Stuey, its usually a pretty indication of whether the device is charging.

    When the lamp lights dimly all the time it can indicate there is shorted main diode or even field diode fault.


    regards


    Robert

  11. #11
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    Quote Originally Posted by robmac
    Actually the "alternator light" is usually arranged as an indicator of when the star point in the alternator field is not at zero, ie the field has been "excited" and unit is charging. Robert
    Hmm. A sparky I know advised me how to install an alternator light on my old R12 when I replaced the regulator with a solid state one. I was told that it worked the way I said above, so that it also warns you of overcharging...

    Nothing's failed yet, so I don't know. It does go out when I start the car, though!

    Stuey


    2003 PEUGEOT 206 GTi

  12. #12
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    Just satisfied my curiousity...

    ------------------------------------------

    This brings us back full circle to the starting point - the alternator warning lamp. As can be seen from figure 5, a schematic for an actual alternator, there is a path to ground from the field current supply input [1] to the regulator. As a result, when the key is turned on, current flows through the warning lamp, through the resisters, transistors, and field coil, and then to ground, causing the lamp to illuminate. Once the alternator is at full output, voltage from the diode trio, also applied to [1], equals the battery voltage. At this time, with 12 volts on both sides, the lamp is out.
    <CENTER>

    </CENTER>If the alternator should fail, voltage from the diode trio would drop, and once again the lamp would light from the battery voltage. If the alternator output is only a little low, the lamp will be dimly lit. If the alternator fails completely, and the output voltage goes to zero, the lamp will be lit at full brilliance. Conversely, if the battery should fail, and the battery voltage drops, with the output voltage of the alternator on one side and the low battery voltage on the other, the lamp will also light.

    As stated earlier, if the light grows dimmer as the engine is revved up, it is because the alternator voltage is rising with the RPM, producing more voltage on the alternator side of the lamp. The closer the output voltage gets to the battery voltage, the dimmer the bulb becomes. By the same way, if the light gets brighter with increasing RPM, it is because as the alternator voltage increases, it is getting higher than the battery voltage. The higher the voltage with respect to the battery voltage, the greater the voltage difference across the lamp, and the brighter it gets.


    2003 PEUGEOT 206 GTi

  13. #13
    Real cars have hydraulics DoubleChevron's Avatar
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    Stuey,

    your understanding is basically the same as mine (though I never have investigated it in depth by drawing up a circuit diagram).

    seeya,
    Shane L.
    'Cit' homepage:
    Citroen Workshop
    Proper cars--
    '85 Series II CX2500 GTi Turbo I
    '63 ID19 http://www.aussiefrogs.com/forum/showthread.php?t=90325
    '72 DS21 ie 5spd pallas (last looked at ... about 15years ago)
    '78 GS1220 pallas
    '92 Range Rover Classic ... 5spd manual.

    Yay ... No Slugomatics


    Modern Junk:
    '07 Poogoe 407 HDi 6spd manual

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