iiyama ProLite X486S dead / power supply issue

Discussion in 'General Electronics Chat' started by kbs1, Feb 16, 2012.

  1. kbs1

    Thread Starter New Member

    Feb 16, 2012
    1
    0
    Hello, my iiYama ProLite x486s monitor has just stopped working. I have tracked it down to be (probably) power supply / inverter board issues.

    The monitor is dead. When assembled (in plastics), it only shows orange (standby) LED. It's supposed to show blue led when ON. This led shines, but shines very faintly, so that it's invisible through plastic.

    When disassembled, the blue led is visible - faint - and display is dead, no picture.

    I have found a similar thread [ http://forum.eserviceinfo.com/viewtopic.php?t=23775 ] that said resoldering dry joints around L101 fixed the problem. My board had many dry joints, so I found L101 (on mine it's L901) and resoldered it together with all other dry joints I could find. No luck, still the same. Capacitors are OK (visually). Board is visually OK. Transistors are not shorted (I hope).

    The problem, I suppose is that on the main connector (to monitor main board), the voltage on pin 12 is 12V when in standby - however when turned on (faint blue led shines), the voltage drops to 9V. On pin 3 (5V line I presume), the voltage drops from 5V to 1V. I think the monitor wants to display "no signal message", because after a while it goes to standby again (strong orange led shines) and the voltage again rises up to 12V/5V on said pins of connector.

    I'm just guessing here. Also, when I press the power switch on the monitor, the PSU (don't know which part) makes a high pitch / frequency noise for about ~2 seconds [voltage is now STILL 12V/5V BUT blue led shines faintly anyawys], after this period the noise stops (complete silence) and the voltage drops. After a while (~10s) the monitor goes to standby, no noise from PSU any more, and strong orange led shines. The voltage rises up again to 12V/15V.

    This repeats when I turn it off via power button and on again.

    It just completely died all of the sudden. No issues before whatsoever. Any help on what parts to check or what could be the problem would be great.

    Also, the psu part number is 715G1236-3-AS, but I have been unable to find a datasheet for it. I don't even know the correct connector pinouot, so maybe the voltage drops are normal.

    Another question: If I would replace the inverter + psu board with another one, say from a LG monitor, would it work?

    Thanks!
     
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