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No singal on screen what could be problem?

Discussion in 'Hardware' started by zr79, Jan 5, 2010.

  1. zr79

    zr79 Byte Poster

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    I am getting a "no signal" message from a flat screen for a PC.

    I have stripped down the PC to just cpu + ram + mobo + psu.

    I have tried new ram and a new cpu. Which really leaves, mobo, psu or screen.

    Now the fans spin ok and the screen does show the Acer logo when you turn(when you actually switch the screen on/off not when the PC boots etc) it on so i assumed the screen is ok but i will cable the PC to my laptop tomorrow to see if it is the screen. Which really leaves the PSU or mobo.

    But as i said the fans spin ok, i thought maybe the PSU has lost a bit of power and although the fans spin it is not supplying enough power, obvious thing is to try a new PSU, anything else i have missed?

    Also the board has onboard gfx maybe they have packed in although i have never heard of that.
     
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  2. Sparky
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    Sparky Zettabyte Poster Moderator

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    Does the monitor have a DVI and a VGA input?
     
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  3. zr79

    zr79 Byte Poster

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    vga only, i should say i have also tried another vga cable, there is only a vga port on screen.

    Ahhh wait a sec, i said the screen shows the acer logo when it is switched off/on, now what i was doing was switching the screen off and then back on while it was plugged into the pc so maybe it was picking up the pc, unless the flatscreen has some kind of built in bios or whatever that will display the acer logo for about 2 secs each time it is switched on.

    If the screen is picking up the pc even for a sec or two then maybe the screen has problems?
     
    Last edited: Jan 6, 2010
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  4. GiddyG

    GiddyG Terabyte Poster Gold Member

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    Have you tried plugging the screen into your laptop?
     
  5. zr79

    zr79 Byte Poster

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    screen? you mean pc??
     
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  6. nugget
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    nugget Junior toady

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    These days the screens usually do that whether they're plugged in to the pc or not.

    Do you have another graphics card you can try?

    Does the pc go through the full boot cycle and load the OS? I know you can't see anything but there should be a lot of disk activity happening for a minute or 2 after turning it on.
     
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  7. GiddyG

    GiddyG Terabyte Poster Gold Member

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    Nope. I meant your flat screen monitor with the vga cable. I would imagine your laptop has a vga connection that you can plug it into. You can then check if the monitor is the issue. If you can get the laptop display up on it, then it isn't the monitor that's the issue...
     
  8. UKDarkstar
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    UKDarkstar Terabyte Poster

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    Yeh, always start with basic diagnostics before wading in and changing items - otherwise you won't know where you are.

    So :

    1) (I'm assuming this is a desktop machine ?) Plug another monitor in and see if it works

    2) plug screen into another PC and see if it works

    3) look closely to make sure there is def no output to monitor - sometime there's the briefest of flashes of POST info

    4) watch the monitor power button - usually changes colour when it detects signal from PC

    5) then I would check graphics on PC - you say it's onboard so difficult if you can't get any output (an presumably can't see to get into BIOS ?) so plug another card in (PCI/AGP/PCIe etc) and see if you can get an output from that (WARNING - some m/b's need you to set BIOS to PCI/AGP card etc rather than onboard so even if you plug another card in and DON'T get an output you can't def assume it's dead)

    Results of all the above needed before you can take it further
     
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  9. greenbrucelee
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    greenbrucelee Zettabyte Poster

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    Try the above but have a look to see if the hard drive is active as you say the fans spin so that indicates there is power from the PSU but obviously does not indicate that there is enough power. What are the specs of the system (include everything).
     
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  10. zr79

    zr79 Byte Poster

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    Well after much swapping about, it seems as though boththe mobo and cpu have gone, unheard of to me, both going, but the psu, ram and screen are fine - fact, i have tried the cpu in various other boards but nothing also i have tried other cpus in the mobo but nothing, again the fans spin though, i put this down to unique, any thoughts?
     
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  11. Raffaz

    Raffaz Kebab Lover Gold Member

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    Have you got another PSU that you can test, ive had similar problems like this in the past and replacing the PSU has resolved the issues.
     
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  12. greenbrucelee
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    greenbrucelee Zettabyte Poster

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    LIke I said just because the fans come on and other components seem to be working does not mean the PSU is ok or outputting enough clean voltage on the 12v rail.

    As Raffaz said try another psu perferably a good one or you could test the current one with a multimeter and see if it is outputting the correct voltages.
     
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  13. zr79

    zr79 Byte Poster

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    Turns out was mobo.
     
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  14. GiddyG

    GiddyG Terabyte Poster Gold Member

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    At least you found out what it was. Congrats on that.
     

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