LCD Backlight on, nothing on screen at boot

  • TheLQ

    Randomly this morning when I turned on an old laptop, the backlight came on but nothing came on screen. Okay, thats weird, but I wanted to see what would happen. So then the lubuntu login screen came up, and the entire screen is a bunch of light blue vertical lines, the same color as the login screen.

    I've tried lots of things, including goofing around with the screen, pulling up the recovery console, and running on battery. Nothing worked.

    Last night someone else used the laptop and they said they did nothing out of the ordinary. Just used it and turned it off, leaving the power plugged in as normal.

    The only issues I've had with the LCD is the LCD not even coming on at boot (A well known issue to this Laptop line) and randomly the screen will go black with some white-ish hue at the top for a second or two then go back to normal. I've never seen it where the entire screen is vertical lines.

    Any suggestions?

  • Answers
  • Torben Gundtofte-Bruun

    This sounds like a hardware failure to me, not a software problem, especially since it's had some similar problems before. Stewart's suggestion to try a live CD will rule out the software question.

    Either the signal cable to the screen has developed a fault, or the supply of power to the screen is dying. In any case, I'm pretty sure that some bit of hardware needs to be replaced. Depending on the age of the laptop, that might not be the best use of your money. Perhaps it's wiser to buy a new laptop?

  • user43588

    on boot after the bios screen has finished, press "esc" to bring you into the grub boot menu, if you have older kernel boot options try them to see if it's an issue with an updated kernel.

    If there are no other boot options shown to you, or if GRUB doesn't show up try a live CD (such as the Lubuntu install disk). insert that and try to boot from it. It could be just a broken graphics driver or inadvertently changed xorg config.

    If the machine boots from cd, your monitor is fine. If not, try another live cd (such as system rescue cd)...

    I think that's enough to get you started. .. Or a least booted into an os of some sort.


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  • John Rudy

    I was replacing my father's computer this past weekend, and he brought up a problem he'd been having with the "new" monitor my cousin recently gave him. ("New" is a very relative term; this monitor was new to my father, but definitely a couple years old. Unfortunately, I don't remember the manufacturer and model number.)

    The symptoms started perhaps 2 weeks ago -- that is, prior to me going out there and replacing the system. (So we can eliminate that change as a possibility here.) When he turns on the computer and the monitor, a massive white spot appears in the upper right corner of the screen, then steadily grows to fill the entire screen. About 2 - 3 minutes later, shutting the monitor off and then turning it back on will bring the screen (mostly) back to normal.

    (By "mostly," I mean that it will be usable, but you will see what appear to be horizontal refresh artifacts for another 30 - 40 seconds. After that, it'll be fine until the monitor is turned off again.)

    Is this an issue with the backlight starting up? Is the monitor on its last legs? Has anyone encountered anything like this?

  • Related Answers
  • William Hilsum

    Dead no, last legs, yes!

    It really depends on make/model, but this usually means a problem with the back-light / control circuit.

    If it is a "few" years old, it may be worth seeing if the manufacturer has a 3/5 year warranty you can claim on.

    I had this on a old Samsung monitor, I used it on a server where I only needed to turn it on once every week or so for 20 minutes, it lasted a further 2 years before it finally died (but this was low usage), if you are using it constantly, it would most likely be quicker so get a standby monitor ready!

  • Dave

    Inspect the power supply capacitors, and any other capacitors. There is an ongoing problem with poor quality capacitors in all kinds of electronic equipment manufactured between 1996 and 2007.

    Alternatively, replace the power supply board entirely.

  • Simon Sheehan

    Yes, It sounds like the capacitors in the power supply are about to go out. This is a very common problem. We repair monitors all the time with issues like you are having. Here is a link to a web page that shows what to look for on the power supply board and what needs to be changed to repair the board.

    If you can solder then you should be able to repair your power supply board yourself. If normally involves replacing from 4-10 blown capacitors and then the unit will be as good as new. It's worth checking it out before you trash the monitor.

    You could try looking at CCL-LA