Blown power circuit in a PC 9821 NA9

Discussion in 'Repair, Restoration, Conservation and Preservation' started by Tokimemofan, Dec 6, 2018.

  1. Tokimemofan

    Tokimemofan Intrepid Member

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    Just got this off eBay, a prior owner did a capacitor replacement. There is a short circuit somewhere that is causing it to smoke when you press the power button. Any ideas?
     

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  2. awbacon

    awbacon Spirited Member

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    I'd pull the caps and start over. Make sure there aren't any bridged solder points from his solder job. If there is a short, I'd be looking for bridged pads first. Then I'd redo the sellers work second
     
  3. Tokimemofan

    Tokimemofan Intrepid Member

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    The circuit seems to be a buck converter used to power the cpu. On closer inspection I see black ooze. The mosfet may not have failed but more likely some thing on the other side. I won’t get to a soldering iron until Monday. That board needs to come off...
     

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