Salvaged LCD Monitor doesn't display anything

Discussion in 'Screens' started by Tech Flare, Jun 10, 2017.

  1. Tech Flare .

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    Ok, so I decided to follow this tutorial by DIY Perks:


    And try to make a DIY Laptop monitor from an old Laptop screen. I started by salvaging a 12 year old laptop that still worked but was so slow it couldn't be used. It was an HP Compaq computer (can't remember what it was called).

    Then I bought a controller board for it, and when I plugged it into my laptop (an HP Pavilion x360 I think) via HDMI the screen didn't turn on and the LED indicator kept flashing Green (on), red (off, but receiving power), and no light (completely off), so then I tried just plugging in the backlight to the controller board and it worked fine.

    After that I tried using a VGA cord connected to a different laptop (a Toshiba Sattelite L505) because my laptop doesn't have VGA in, and I could tell the LCD Screen was receiving a signal because when I changed projection from Extend to duplicate both computers flashed off and then back on, but the LCD Screen still only showed the backlight!

    And that's when I decided to make this post because the screen worked when it was connected to the laptop, but for some reason it doesn't now. Maybe it's a controller board problem? Anyway, any help is appreciated!
     
  2. Aurelio The Fixer ᕕ( ᐛ )ᕗ Staff Member . . . .

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    Hmm in my opinion you either got a defected driver board or the power supply you're using for it can't provide enough current to power the display, so its voltage drop and the board resets itself over and over
     
  3. Tech Flare .

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    About the second part of your answer - how would I go about checking if I have the correct amount of current for the board? I have a multimeter, but I recently bought it and I’m pretty noobish at electronics, so I don’t know how.
     
    Last edited: Jun 11, 2017
  4. cheese the tallest memer in town Staff Member . . .

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    The power supply should be labeled as to how much current it can supply, and the driver should be labeled as to how much current it requires. Just make sure the current is higher on the supply than the current needed on the display
     
  5. Tech Flare .

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    Okay so have a 12.6 volt supply and the controller board needs 12 volts, will that work?
     
  6. Spencer Richardson .

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    That's the voltage. You'll need to know the amperage(amps). it will be given as mA(milli amps) or A(amps). On the power supply, this value is usually found close to where the voltage is shown. Hopefully that makes sense and helps. :)
     
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  7. Tech Flare .

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    Ok the supply outputs 1 amp, but when I tested the board with my multimeter I set it to milliamps and it just said 0.00. Maybe I'm doing something wrong?
     
  8. GingerOfOz no wario Staff Member . .

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    With a multimeter, you need to always set your meter higher than what you think the amps/volts/ohms will be. Otherwise you won't get a reading, and you could blow a fuse.
     
  9. Spencer Richardson .

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    Finding the amperage using a multimeter is a little different than finding other things like voltage. You can always YouTube how to do that. :) but it will honestly probably just be easier to check the data sheet for your board to see how many amps it requires to work properly. Do you have access to a data sheet?

    Edit: changed soars to board.. that's kind of an important detail. Haha
    If you got your board from ebay, there is sometimes a data sheet if you look in the product details
     
    Last edited: Jun 11, 2017
  10. Tech Flare .

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    I tested the amps and the board has about 1 amp as well as the power output. Also here is another update: now the screen does not even show the backlights when plugged into my toshiba laptop via VGA :/ the power indicator still keeps flashing green, red, and then no light at all too :(
     
  11. Madmorda Painting Queen Staff Member . . .

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    I just want to clarify for future readers that you can supply more amps than needed but should NOT supply more volts than needed. You want your voltage to be correct, and your current to be at least enough.

    For example, if you have something that requires 5v, 1A, it is okay to give it 5v 2A. It is not okay to give it 12v 1A.
     
    Matthew, Stitches, GingerOfOz and 2 others like this.

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