X39 - no image after using 4k120

[sparker599]

I got 4k120hz working on my computer and started using it on my x39. I'd been using mostly 4k60 for over a year before. After just a few hours of use at 4k120, the image suddenly turned black and since then, I haven't been able to get it to show any image, even the monitor's green crosshair.

The brightness still increases and decreases when I raise/lower brightness or enable/disable scanning mode. The monitor is still recognized by Ubuntu and the 2 green LEDs on the tcon are lit.

The monitor was not displaying its temperature warning when the image turned black.

What might be causing this? I've checked all the cables except the wide ones near the heatsink. It couldnt be those, could it? If one of those came loose, it would just affect one half of the monitor, correct? Will need to disassemble further to get a good look at those.

[ZisWorks]

Try this:

Unplug the two DP cables and the power cable.  Plug the power cable back in.  Hold down the power button for 10s.  Do you get test mode?  I'm not sure if your unit has the test mode feature, but if it does have test mode, the tcon will turn on  (two green lights), backlight will turn on, and there should be a colored box pattern on the screen. 

A: Backlight turns on and you get green lights, but there is no pattern on the screen, it could be a panel bias supply problem (exchange tcon).

B: You get the full test mode image displayed properly, it could be a DP chip problem. (exchange tcon)

C: nothing happens at all: Test mode is not implemented in your firmware, proceed to other diagnostic steps (we'll do a videocall)

Probably issue A.  Easy for me to fix, don't worry about warranty period.

Thanks,

zis

[sparker599]

No, I don't get test mode. In fact, the backlight doesn't even turn on.
I remember the firmware was v054, in case that matters.

[novalidaddress]

To jump in on this, I have also had this issue with my x28 for the past 2 months.  When I update the GPU drivers I can get an image to display and everything works properly.  However, if the computer goes to sleep or is turned off, then the display will not show an image.  The computer detects there is another screen but no change to the monitor settings will cause an image to display.  I have an x39 that works fine as well and am not experiencing any issues after a few driver updates to the GPU (maybe 5 months ago since any issues).  

[ZisWorks]

Different issues.  Your x28 may have a problem with one of the DP chips or cables.  Let's do a videocall to sort it out.   Sending contact info seperately.