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HELP Miller XMT 450 No Voltage

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  • HELP Miller XMT 450 No Voltage

    HELP Miller XMT 450 No Voltage

    When trying to stick weld, the amps show correct but the voltage bounces around at a volt or less.

    The green led is flashing on the top board and a faint click is coming from the “wind tunnel” area. The LED and click are in sync.

    The 2 1000V .34MFD capacitors have been replaced.

    I have tested the 4 capacitors, diodes, resistors, coils, and the IGBTs with a Fluke multimeter. Ive checked the 4 output diodes. Everything seems to check good.

    I’ve pulled all 3 boards and visually inspected for burn marks, bad solder joints or bad connections. I’ve done my best to test components in the circuits and found nothing there either.

    The 480/460 voltage IN is good. The voltage off each IGBTs is around 340VDC I think. I need to check again. There is no voltage at the main output when checked with my meter.

    Is there a drawing that gives me information where I can check test points?

    Does anyone know which direction I should go next?

    I am on a ship so it’s very difficult to send this in for repair.

    Thanks for any your help or any suggestions you can give me.

    XMT 450 CC/CV

    Stock # 907481

    SN# MC480050U