Issue with ZBook Studio G3 LCD backlight not functioning
Issue with ZBook Studio G3 LCD backlight not functioning
Hi,
The LCD backlight on my HP ZBook Studio G3 isn't functioning properly. With a flashlight, I can see the display is operational, so it's not completely dead. I think it might be a blown backlight fuse or a damaged backlight unit. Do you know where the display backlight fuse is located? I checked the "HP ZBook G3 Backlight Fuse Location" and disassembled my laptop, but the only fuse I found seems to be intact—my multimeter test a few nights ago showed around 2-3 Ohms. I'm not certain if I'm testing the right fuse.
The images attached show both sides of the motherboard. The fuse I located and tested is labeled "F2" with a prominent red arrow.
If this is indeed the correct fuse, then the backlight appears to be faulty. If that's the case, do you have any advice on where to buy a replacement or instructions on how to install it?
Thanks,
Thank you for your note. I noticed the initial mention of "HP ZBook G3" was incorrect—it should have been "HP ZBook Studio G3." This clarification will help avoid confusion about the fuse location and ensure accurate information.
I have examined the video ribbon cable. I can only plug and unplug it on the motherboard side; I’m unsure how to detach the display to access the connector inside. It seems the cable might be defective. The screen would brighten briefly when I moved the hinges (opened or closed the display lid), but this no longer happens.
I’ve taken apart the laptop to remove the cooling and battery, and released the display from its base so I could move around the video ribbon cable in search of the backlight. This didn’t work.
Could you suggest possible next steps? Do you have any instructions on how to disassemble or separate the display to reach the connector? Also, when does the HDMI activate? I’m having trouble getting anything from the HDMI output, so is it also affected by the same issue? Does HDMI activation happen after the OS has booted up?
I was able to separate the display and inspect the connector. It seemed okay at first, so I unplugged and reattached it just to test. I also checked the other connections that came from the video ribbon cable—one went to the webcam and the other to a small circuit board near the display connector. Maybe that's where the microphone is.
I didn’t find any separate backlight module. Should I replace the entire LCD if the backlight is damaged? I recall fixing another laptop model, possibly from Asus, about ten years ago when the backlight failed. I ordered a replacement from Aliexpress and it worked.
What advice do you have? Should I consider getting a new display? If so, would it be wise to check for other issues on the motherboard, like a blown fuse, before ordering? Anyone have suggestions?
Also, when does the HDMI start working? I’m not getting any signal from the output, so is this also affected by the backlight issue? Or does HDMI only activate after the system has booted up?
The OS won’t start, and I’m struggling to read the screen with a flashlight. White text on black is nearly unreadable. Black text on white, like the error messages when changing RAM or storage, can be seen clearly with a flashlight and are usually legible without one.
This is solved now. And it's... weird. This is what happened:
I was shining a flashlight at the display to be able navigate the BIOS settings, to check boot order among other things. (The flashlight wasn't strictly necessary but it sure made it easier to see that was on the display.)
I noticed that the date was set to Jan 1 2015, perhaps due to the CMOS battery having been disconnected when I removed the motherboard looking for the display backlight fuse.
So I set the date (and time) and continued working my way through the BIOS settings. I switched from the "Main" menu to "Security", and checked each value. Under the heading "Utilities" the first entry is "Hard Drive Utilities". I pressed Enter to check those values, and suddenly the display lit up!
And after that the backlight has continued to work. The laptop has been turned off for a couple of days, and when starting it today the backlight still works.
So... what could have been the cause for the broken backlight, and what was the actual fix?
Was it the date/time setting? Seems extremely weird and unlikely, especially since the date/time was OK back when the backlight stopped working (2-3 years ago), and also since the backlight didn't come back on right after setting correct date/time, it took a few minutes to check other BIOS values before I reached "Hard Drive Utilities".
Was I too eager in my previous attempts, not leaving the laptop turned on long enough for the backlight to start working again? Seems unlikely, the laptop had been turned on for perhaps 10 minutes when the backlight started working again, and I'm 99.9% sure I've had it turned on for longer than that in previous attempts to make the backlight come back.
Was it pressing Enter to check "Hard Drive Utilities" that fixed it? Yeah, please explain the logic in that one.
Anyways, however unlikely it seems that my steps will help someone else fix their display backlight problems, I thought it best to post this for future reference.
(Oh, and the boot problems? They were due to UEFI and Secure Boot settings. Don't remember exactly what I changed to make it work, I think "Enable MS UEFI CA key" was inactive so I enabled that, and perhaps something else. 1-2 years ago I was fiddling around with boot settings to try and boot a Linux USB stick to enable ssh access and troubleshoot from within Linux, but that effort ebbed out and I must have left the boot settings in a bad state.)