need help on my LG lcd monitor

Discussion in 'General Electronics Chat' started by ampdeck, Apr 20, 2009.

  1. ampdeck

    Thread Starter New Member

    Apr 14, 2009
    Hi guys please help me with my LG lcd monitor. i bought this monitor last year "LG lcd monitor L1552S" and the dc power that powering my device is an external adaptor. My problem is that my aunt lost it and I couldnt find it any more and was planning to use my PC power supply with (12v 25a) and my LCD has 12v 3a.

    My problem is on how to know the correct dc polarity my monitor since it has no label at the back of my monitor..... please help or ill just assume that the center of my female plug is positive but still im scared to try it....
  2. Darren Holdstock

    Active Member

    Feb 10, 2009
    Scared is good - you've got a 50/50 chance of getting the polarity right as there is no convention for DC power plugs. If I ruled the world I'd make the centre pin +ve, but usually it's -ve.

    Alas the only way to make sure (and the LG manual is no help here) is to take the monitor apart and take some clues from the power supply circuitry. There'll probably be an electrolytic capacitor across the DC input and you can take the polarity from that; if not you'll have to look up the datasheet of the first IC the 12V input feeds into.

    Statutory electrocution warning: The CCFL backlights on LCD screens can have about 1000 V on them, so please mind how you go.
  3. Externet

    AAC Fanatic!

    Nov 29, 2005
    Check for zero ohms from any metal chassis part on the monitor to which power connector input pin. That will be negative.
  4. ampdeck

    Thread Starter New Member

    Apr 14, 2009
    thanks much guys... I appreciate it.