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monitor screen goes black when connected to computer

Discussion in 'Hardware' started by medlearner, Nov 16, 2019.

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  1. medlearner

    medlearner Thread Starter

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    I have an old Dell Desktop Slim PC. When I found it, it had a Pegatron video card (which connected via one of the PCIe slots but it also connected to and drew power from the power supply unit) in it but unfortunately this was removed and sold before the computer could be tested. There are VGA and HDMI ports on the motherboard, but without removing the CPU fan and glue I cannot confirm whether or not there's an on-board graphics card. Dell were not forthcoming and refused to provide me basic information about the device since the warranty has expired.

    When I connect my monitor (which is definitely functional; I've tested it out with another computer) directly to the motherboard's VGA port, the monitor screen goes black. I have tried 3 different graphics cards, all of which have DVI ports, and connect them to the monitor with a DVI-VGA adapter and the screen again turns black. Interestingly, one of the graphics cards has a fan on its side and this fan does not activate when the computer turns on.Also, the monitor screen turns black even when connected to the turned-off computer I haven't been able to test the HDMI port on the motherboard yet, because the HDMI-VGA adapter hasn't arrived.

    What I cannot determine is whether there's a hardware-level fault with the motherboard, or just some incompatibility issue with the motherboard and the graphics cards that I've put in the computer, but since I've tried 3 different graphics cards, I am doubtful. The only other clue is that I can turn the computer on by simply pressing the power button and the power unit turns on, but then in order to turn the computer off I have to physically disconnect the power plug because the power button becomes unresponsive. Perhaps this says something about the motherboard.

    I removed the small 3V cell battery from the motherboard for a few minutes and then re-inserted it, in order to reset the BIOS settings. But this does not change anything. I have also tested the 3V cell battery in another computer and the battery worked fine. I then replaced the 3V cell battery in the motherboard with another working 3V cell battery. But this did not change anything either.

    Upon someone else's suggestion, I have tried connecting the computer to the internet (via ethernet cable) and turning on the PC, but this too has made no difference.

    The computer had a blank SSD connected to the motherboard. This shouldn't have posed any problem since the computer should boot into BIOS but, just in case, I replaced the SSD with another SSD that has a working operating system (Ubuntu) installed on it. Again, this did not resolve the problem of the black screen.

    I can provide more detailed specifications about the various hardware components if this will help you further. I don't know that much about (in)compatibility issues between graphics cards, motherboards and power supply units. I can also send some photos if it will help.
     
  2. Macboatmaster

    Macboatmaster Trusted Advisor Spam Fighter

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    Please supply full model number and serial number
     
  3. medlearner

    medlearner Thread Starter

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    Service tag: 39v484J
    Express service code: 07126807843

    Hope this helps. Dell were not forthcoming when I contacted them. And their website does not provide anywhere enough information about past models of Dell computers that I need. But perhaps you will have more luck than me. Thank you.
     
  4. Macboatmaster

    Macboatmaster Trusted Advisor Spam Fighter

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    Reset the current CMOS settings: WITH POWER DISCONNECTED


    a. Locate the 3-pin CMOS jumper (CLEAR_CMOS) on the system board

    b. Remove the jumper plug from the CMOS jumper (CLEAR_CMOS) pins 1 and 2.

    c. Place the jumper plug on the CMOS jumper (CLEAR_CMOS) pins 2 and 3 and wait approximately five seconds.

    d. Remove the jumper plug and replace it on the CMOS jumper (CLEAR_CMOS) pins 1 and 2.

    https://downloads.dell.com/manuals/..._desktop/studio-slim_service manual_en-us.pdf

    Does the screen show anything - on power up of the computer
    and then go blank after POST
     
  5. medlearner

    medlearner Thread Starter

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    Hello, thanks for this and sorry for the delay.

    This makes no difference. The monitor screen is always black whenever it is connected to the computer (either via the built-in VGA or HMDI ports or any of the three graphics cards I've tried). Because the screen is always black, I can't tell if the computer is entering into POST.
     
  6. medlearner

    medlearner Thread Starter

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    What I can observe is that the fan on the CPU activates when I turn on the computer. But the fan on one of the graphics cards does not activate. I don't know what this means.
     
  7. Macboatmaster

    Macboatmaster Trusted Advisor Spam Fighter

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    Found it where please
     
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