ThinkPad X300 - no backlight issue

I got a ThinkPad X300 on a flee market, it's great but there is one problem - the screen is extremely dark because the backlight doesn't turn on.

I removed the ThinkPads screen frame cover and took a couple of photos. Here is the album. Do you guys spot something that looks wrong, like a misplaced or detached cable? What I tried so far to fix the issue:

changed display to bright in BIOS - no effect
changed brightness via keyboard - no effect
attached an external display - the output from the ThinkPad looks just fine on it
removed the battery and drained the power - no effect
removed the CMOS battery - no effect (just removed the "power on" lock)

How to fix that issue?

Matt

Posted 2017-07-05T21:43:20.590

Reputation: 59

Is the display dark all the time (in BIOS etc)? – Klinghust – 2017-07-08T18:29:29.367

What OS are you using? What video card drivers are installed (version number, free/nonfree/repository/custom etc)? – styrofoam fly – 2017-07-08T20:54:43.890

@Klinghust Yes, it's dark all time. – Matt – 2017-07-09T13:50:54.670

@styrofoamfly OS = Ubuntu 16.04.2 LTS, there is no HDD - only an USB 3 32GB Drive. Where can I find the video card drivers details? – Matt – 2017-07-09T14:03:14.950

@Matt then I guess it is hardware related. Using an external display, changing the display or just getting rid of the whole laptop is, IMHO, your only choices. – Klinghust – 2017-07-13T08:19:18.327

Answers

The most common cause of the problem you describe is not a failure of the screen itself but of the inverter that powers it's backlight. The inverter is not visible in the pictures you shared as it's usually mounted to the backside of the monitor.

You can see the inverter for this other laptop in the video at about 4:14 (the circuit board attached to the back of the display panel). I found inverters for your laptop being sold on eBay with a going price of ~$35.

Backlights on laptops rarely fail and if you can see images on the screen, even really dark ones, then the screen itself is probably working. But inverters going out is not that uncommon and results in exactly the symptoms you describe. And it's a $35 dollar part, so you can afford to buy it and try it without much risk to your wallet. A replacement display panel can run you >$100 and, if it's the inverter, it will be wasted money.

EDIT: Apparently that video went from being of a ThinkPad X300 to an Acer Aspire somewhere between me finding it on a random website via google and grabbing the share link from YouTube directly. However, the rest remains the same.

Cliff Armstrong

Posted 2017-07-05T21:43:20.590

Reputation: 1 813

Chances are that the screen itself is shot. The LED back light could have blown. Try plugging in an external monitor, if this works fine then it is definitely time to replace the screen. IT could, but not likely, also be the fuses on the motherboard. There should be a 2 amp and a .5 amp fuse near the plug.

Bmize729

Posted 2017-07-05T21:43:20.590

Reputation: 186

Thanks for your answer. Is it possible to repair a blown fuse? – Matt – 2017-07-11T11:37:56.420

It is, if you have the right equipment and know-how. I would honestly focus on the screen because that is the easiest and often the correct solution. – Bmize729 – 2017-07-11T23:40:38.867