nighthawk 550 electrical problem

Discussion in 'Motorbike Technical Discussion' started by jlpridge, Sep 23, 2005.

  1. jlpridge

    jlpridge Guest


    The battery is brand new as of monday. I am purchasing a multimete
    today to start testing stuff. I have not received my clymer manual ye
    so I am not sure how to test the rectifier and the stator. If any o
    you have any info on that it would be most helpful
     
    jlpridge, Sep 23, 2005
    #1
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  2. Charging voltage test:

    With a fully charged battery installed, start the engine. The
    headlights must be on to load the alternator. Hook a voltmeter across
    the battery with the voltmeter on a 15 to 20 volt DC scale. As you rev
    up the engine, the
    voltage should rise from 12 volts to about 15 to 16 volts. Then the
    voltage should drop off sharply. Roll off the throttle and roll it back
    on and the voltage should rise and sharply fall each time you do this.
    The charging voltage test will prove that the voltage regulating
    circuit works.

    Open circuit test:

    With the alternator plug disconnected from the voltage regulator, hook
    your voltmeter across any pair of AC output wires. There should be
    three AC output wires. The stator is Y-wound with a floating neutral,
    so the AC current goes from A phase to B phase to C phase and you can
    read the same AC voltage across any pair of wires. You should read
    around 90 to 120 volts AC as you rev the engine up. DO NOT RIDE THE
    MOTORCYCLE WITH THE AC OUTPUT PLUG DISCONNECTED. You can fry the
    insulation on that expen$ive stator.

    Stator continuity test:

    Set the ohmmeter on the R X 1 scale. As above, it's a Y-wound stator
    with a floating neutral, which means it's not supposed to be grounded
    to the engine. Check continuity on R X 1 scale from any wire to any
    other wire. It should be around 1 ohm. If you have a digital ohmmeter,
    you may not be able to zero out the lead resistance, so the resistance
    might be around 2 or 3 ohms. No problem.

    Switch to the R X 1000 scale and check all three leads to the engine
    block. You shouldn't get any reading.

    About the rectifier part of the RR unit:

    There are six power diodes inside the rectifier regulator. They change
    the AC input to a DC output. AC comes in through three wires, and DC
    comes out of two wires. Sometimes the rectifier case has to be grounded
    to the sheet metal plate that it's bolted to. If you look at bolt holes
    in the plate, check to see if all the paint has been removed around one
    of the bolt holes. That's a grounding point.

    Also, look at the back of the rectifier regulator. If it has some white
    sticky stuff on the back, that's heat sink compound that was used to
    transfer heat from the rectifier regulator unit to the sheet metal
    plate it's bolted to. Diodes get hot due to internal resistance, so the
    heat is radiated to the air through the fins and conducted to the sheet
    metal plate.

    The diodes are arranged in a three phase full wave configuration. If
    you look at the diagram on www.electrosport.com, you'll see the three
    AC inputs attach between pairs of arrowhead symbols. Those are the six
    power diodes.

    The convention is that the input current can only flow in the direction
    of the arrowheads.

    The diode test:

    This works best with an analog ohmmeter, as some digital meters won't
    read a diode correctly. With the ohmmeter on the R X 1 scale, check
    from each AC pin in the alternator input connector on the voltage
    regulator to the DC positive output pin.

    You should be able to tell the AC input connector from the DC output
    connector because it's probably impossible to hook the AC input
    conector to the DC output connector, the connectors should be "keyed"
    differently.

    To check the first three diodes, touch the black lead's probe to the AC
    input pin and the red lead to the DC output pin. If you don't get a
    reading, check with the black lead from the AC input pin to the DC
    output pin.

    You must get the SAME reading from each AC input pin to the DC output
    pin. It might be around 15 ohms, but I can't say for sure because the
    battery in an ohmmeter biases the diodes and causes different readings
    depending on the ohmmeter. If you don't get a reading, that probably
    indicates a blown out diode.

    Now, reverse the leads and check the other three diodes. Whatever lead
    gave you continuity from the AC input pin to the DC output pin is the
    wrong lead, so reverse the leads and check from the AC input pin to the
    DC negative ground pin. Again, you must get the same low reading from
    each AC input pin to the DC negative output.

    You should NOT get a reading in both directions, that indicates a
    shorted diode. You SHOULD get the SAME reading through all six diodes,
    going first from the AC input to the DC output to check the first three
    diodes, then reversing the leads and checking from the AC input to the
    DC negative side.
     
    krusty kritter, Sep 23, 2005
    #2
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