Monitor powers up but report No Signal

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  • Alex Atkin UK
    Member
    • Sep 2005
    • 23

    #1

    Monitor powers up but report No Signal

    I have a 15" LCD monitor which I have been holding on to for over a year now. It worked perfectly when I bought it second hand but suddenly after relocated the PC it stopped working. It powers up but always reports "no signal" then enters power management mode, as if the VGA cable is not plugged in.

    I always in my gut suspected it was fixable so kept it in storage. It helped it has an Elo Touchscreen which are quite expensive.

    Knowing this site, my first instinct is that recapping may simply bring it back to life. One of the caps appears to have been damaged since day one, presumably while applying the positive lead for the touch screen. It obviously did not stop it working but perhaps contributed to an early death.

    The problem is, the only tools I have are 30W soldering iron, some solder, solder sucker and a multimeter. An ESR meter is out of the question, they are too expensive when there are no guarantees I can fix the problem. I probably will pickup a better multimeter with capacitance testing though.

    Any suggestions? It looks surface mount which is probably why I was reluctant to try fixing it when it first died. Its pre-ROHS so perhaps 30W will be enough to do the job? I may possibly be able to get a new soldering iron too but do not want the expense if I can avoid it.
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  • Alex Atkin UK
    Member
    • Sep 2005
    • 23

    #2
    Re: Monitor powers up but report No Signal

    I am clueless what I should be looking for if I am going to replace those caps. Any suggestions?

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    • kc8adu
      Super Moderator
      • Nov 2003
      • 8832
      • U.S.A!

      #3
      Re: Monitor powers up but report No Signal

      check the easy stuff first.
      since it happened when you moved it the top suspects are cable/connector damage and bad solder joints.onc it works again the recap is just p.m

      Comment

      • Alex Atkin UK
        Member
        • Sep 2005
        • 23

        #4
        Re: Monitor powers up but report No Signal

        The PSU plug is in a real bad way, pretty much falling apart. However the connection on it seems alright and with the screen basically powering up but not detecting a signal, I suspect its fine.

        I was considering perhaps I should try for a replacement but it might be hard to find as its a weird 4 pin one and actually the one supplied is HP brand so clearly was not the original one to begin with.

        As there only seems to be those three caps above 100uF it seems a good place to start. The problem is I do not really know what to replace them with. Are they normal or low ESR? Would it hurt to replace them with low ESR even if they weren't originally?

        Comment

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