Motorrad Omega 400 problem

Discussion in 'Airheads' started by Malindi, Dec 13, 2004.

  1. Malindi

    Malindi Zen Adventurer

    Jul 9, 2001
    Vancouver, BC
    I mod a list for G/S bikes (monolevergs on Yahoo) and this question came in. I don't have an Omega, but maybe someone can e-mail Svante and/or post a diagnosis here?


    Got the Omega 400W alternator with replacement diode board installed on
    my '96 GS Basic, and has been very pleased with the performance for some
    10K miles. But this autumn the charge indicator bulb began to
    intermittently refuse to turn off, but stayed glowing partially even at
    full revs. And finally never turned off completely. I thought it had to
    do with my clock sometimes refusing to work, but after fixing the clock
    (found a loose, tiny bulb inside the housing, intermittently
    short-curcuiting the connection) the indicator bulb still stays on
    partially glowing. Voltage is correct (have also checked with another
    regulator installed). Regarding the diode plate I found the checking
    procedure described in "Classic boxer charging" a little confusing.
    Measure gives correct readings between AC input terminals and the D+
    terminal, and also from all the G connections but there is no B+
    assigned. I choosed the connector for the red wire to the starter engine
    (B+ on the Thunderchild board) and then I get bad results, with big
    resistance results in both directions for all the AC input terminals.
    U = 3 vs 1,1 MOhms
    V = 5 vs 1 MOhms
    Y = 7,5 vs 0,8 MOhms
    W = 15 vs 0,7 MOhms
    This seems a little odd, are really all four diodes fried? Giving no
    more noticeable sign then a glowing charging lamp?Or is there something
    wrong with checking the board this way? Has anyone information about the
    correct checking procedure and results for the Omega diode board? Of
    course I will also appreciate information about any specific problems
    noticed with the Omega charging set up so far.

    Best regards

    Svante Brandén, Stockholm, Sweden
    R75/5 '73, LWB, black, "Devil"
    K100RS '87, Motorsport, white, "Hero"
    R100GS '96, Kalahari (mod Basic), white/blue, "Fraka"
  2. Frank Warner

    Frank Warner Traveller

    Mar 14, 2002
    Sydney, Australia
    Diode checking with a meter is dependant on the meter used. Some have a specific range for diodes, others you have to know what they do. Best to check a new diode - that should tell you what to expect when checking other diodes.

    Larger diodes can have a some what different effect on the meter indications. If all the diodes on the board read the same I'd say they are ok.

    The glowing light may simply be that the alternator side is at a higher voltage than the keyed ignition side - that is a voltage drop from the battery through probably a fuse, the ignition key, kill switch to the globe. You would need to do some voltage readings around the circuit to find the problem, not resistance readings. Measure the voltage on both sides of the globe - bet the alternator side is higher than the ignition switch side.