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Cheap variable power supply circuit stopped working

seanspotatobusiness

Sep 11, 2012
193
Joined
Sep 11, 2012
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193
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?

 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
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25,510
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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