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power inverter blew out, diag?

Discussion in 'Troubleshooting and Repair' started by NCC74656, Oct 17, 2013.

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  1. NCC74656


    Jun 6, 2013
    I have a harbor freight 3000W power inverter that blew out on me. i was using a power tool and the two AC lines crossed when the extension cord i was using shorted on me. this lead to the inverter beeping into protect mode but now when ever i turn it on it will climb up to max load in about 6 seconds and beep itself off. the inverter was hooked to a 150A fuse but did not have its little ground terminal hooked up. not the 12V ground but the small spin nut that has the ground symbol on it.

    how should i go about diagnosis and repair of this device?
    i can remove all 4 internal fuses and it will still do this, no fuses blew, there are no poped caps, and no visible burn marks on anything.

    pic: [​IMG]
  2. NCC74656


    Jun 6, 2013
    so i started pulling it apart and i found another fuse buried under some wires. once i pulled this fuse out the inverter powered on and stayed on a nominal voltage. once i reinsert ANY fuse it climbs up to max amperage and shuts off.

    i removed the outlets to see if maybe they had internally shorted but they had not as it still maxes out with them unpluged. so my thinking is that it must be a common path way that links all the power circuits to the monitor that is failing. i can not see any damage anywhere tho so im at a loss as to where i go from here.

    pics: [​IMG]
  3. NCC74656


    Jun 6, 2013
    any thoughts?
  4. shrtrnd


    Jan 15, 2010
    It's just a thought, since you don't have hits so far.
    If you've got an ohmeter (with the unit unplugged and unpowered) start checking
    those seimconductors lined-up on both sides of the boards (The three terminal
    black squares with the silver tabs on the top).
    I don't know what else happened, but I'll bet some of them are blown.
    The IC's might be damaged, but the short-circuit would indicate to me a check of the
    power semiconductors is in order first. (Looking for shorted or open components).
    Good luck.
  5. NCC74656


    Jun 6, 2013
    ill give it a go, one of the terminals is a gate correct? the other two being power and ground?
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