I've got an older Laptop (i5-2430m) basicly for free, because it was "broken". Well, the display doesn't work, but if conncected to an external monitor everything runs fine.
Since the internal display doesn't seem to have any physical damage to it, I'm asking myself what's most likely the problem. I could replace: a) the cable from the display to the embedded displayport (7-10$) or b) the whole display without the cable (50-60$) or c) nothing (if something on the mainboard is broken).
I've inculded a picture of the broken display. I can regulate the brightness over the OS, so some kind of connection is working, but it still could be a broken cable... Maybe someone has some experience with laptop-repair and can point me in the right direction. I just don't want to waste money on parts I don't need
It's likely the display itself judging by the picture. It's doubtful it's the main board since video works on an external display. What probably happened is someone dropped it and it just borked the connection.
Try reseating the cable, and visually inspecting the cable for damage on both ends. If it all looks fine then it's probably the screen.
My Guess since there are distinct lines in the display it may be the display controller on the bottom of the display. Start by checking the motherboard around the display cable connector if something looks burned of corroded. Also see if lightly massage the controller at the bottom of the display to see if that changes the picture to the better (even briefly). That may give you a hint on what is broken at least (display or motherboard)
I would say the screen itself is bad. The connections to the pixels themselves are broken. You can rule out that it is the cable due to the way differential signalling works.
I just got to it and "fixed" it. The "massage" of the controller and reseating the connection (a few times) helped a lot. I used some hot glue to hold everything in place (at a slight angle...) and it works fine for now.
If it breaks eventually, I can still replace the display and controller, since i know now, that the board is fine.
Thought that the massage would work My friends x240 got one pink bar in the middle-right hand side of the display. I then found out that it was the controller that was playing around. I put a piece of tape on the cover to give som pressure on the controller. That have worked for many month now.
Changing the controller may be hard since there is often glued connections (and the controller may be hard to find by itself). But you know what the problem is at leas now.
Pretty much the fix i thought it would be. I had a similar problem with my Lenovo z580 which would do this when it got cold. Issue was a loose solder joint. But could just as well have been a loose connector, it caused the same pattern on screen.