How to fix a black horizontal line that appeared at the top of my HP laptop screen?

[Harvey_00]

I'm experiencing an issue with my HP Elitebook 840 G6 screen where a horizontal black line has appeared at the top. This line initially started from the top edge of the screen and has slowly moved approximately 0.5cm downward over the course of 2 months but the part of screen it has traveled past functions normally without any issue.

This line does not appear in screenshots or in external monitors.

Steps Already Tried:

1. HP diagonistic tools, including display and screen test but no issues detected.

2. I tried the tests outside the OS during boot but no problem found.

Could you please help me in identifying the exact cause and provide guidance on how to resolve it? Is this likely a hardware problem? Would replacing the screen or checking internal connections be necessary?

[Huffer · Accepted solution]

It is likely a defective screen or screen cable. Yes it would be necessary to disassemble to do any kind of diagnosis or repair. The fact that it puts out an image without defect to an external monitor shows it is the screen panel or cable causing the problem, most likely the panel.