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Samsung Syncmaster 732n dead

Discussion in 'Troubleshooting and Repair' started by Blue_fog, Jul 19, 2013.

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  1. Blue_fog

    Blue_fog

    17
    0
    Nov 30, 2011
    Hi guys,
    I have a 5 year old Samsung PC monitor that does not do anything when powered up. No power LED, no LCD backlight, nothing at all. I have taken out the power board and all the caps seem to be alright. I have heard that caps can be bad even when they look visually OK. I want to know is there any way that I can test the caps in-circuit with a cheap DMM? I suspect two 820 micro Farads caps on the baord.

    I also want you to know that the monitor had gone bad earlier also but miraculously, disassembling and reassembling it did the trick. I suspect the logic board also and know that replacing it is next to impossible. Any way of checking the power board caps would be very helpful.

    Thanks.
    :)
     
  2. shrtrnd

    shrtrnd

    3,821
    519
    Jan 15, 2010
    It isn't fool-proof but this is a quick and dirty method.
    Make sure your power is disconnected.
    Put an ohmeter across the cap (discharge it first, by shorting it),
    the ohmeter will charge the cap from the ohmeter battery, and your ohmeter
    readings will rise or fall if the cap is not shorted or open.
    That won't tell you if it's leaking, but it'll tell you if the cap is shorted or open.
    Sounds to me though, since this happened before, that you've got a bad
    connection in your wiring somewhere. Wiggle some wires and try to find it.
    You did check any fuses, didn't you?
     
  3. Blue_fog

    Blue_fog

    17
    0
    Nov 30, 2011
    Hi,
    I checked the fuse and it was alright. I had done this :

    1. Discharged the cap by shortening the leads.
    2. Charged the cap using the lowest possible Ohm setting (200ohms) taking care of polarity.
    3. After 5 sec of charging switched the meter to volts and measured the output.

    On some caps I got about 1 V of immediate output, whereas on the 820 micro F ones I got about 150 mV. That is what made me suspect them. Should they be replaced?

    Thanks

    :)
     
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