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Cheap variable power supply circuit stopped working

Discussion in 'Troubleshooting and Repair' started by seanspotatobusiness, Mar 3, 2013.

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  1. seanspotatobusiness

    seanspotatobusiness

    193
    4
    Sep 11, 2012
    I bought the below variable voltage power supply from eBay last year. It worked fine when it arrived. I left it alone for a while and it seems to have stopped working,

    The component with 330 printed on it appears to be overheating. Turning the potentiometers does not seem to affect the voltage or current output. The voltage is stuck at 0.4 and even when I short the output, I get 10 mA maximum.

    Can anyone here interpret the fault?

    [​IMG]
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,412
    2,780
    Jan 21, 2010
    My guess is that the IC with 5 legs on it has failed with the internal mosfet short circuited.

    The highest resistance part in the circuit is the inductor and now it is complaining.

    Have you measured the input current?

    Oh, and are you using an external meter to measure the output current and voltage?
     
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