w550s/t550 LCD screen replacement - brightness set at max.

Hello,
I replaced the horrible TN panel of the w550s (1080p) with a compatible model (lp156wf4) and now the brightness is stuck on max with no control over brightness levels (fn keys do not work for brightness). Updated video drivers... Anyone know what could be the issue? Thinkpad LCD monitor driver and generic PNP monitor driver do not help fix.

Any help would be great. Thanks!

 

I am having this exact same problem as well. I installed a B156HAN01.2 IPS panel in my T550, can't get the brightness settings to become available. The screen just stays at max brightness....If anyone finds a fix please share....

 

I am receiving the b156han01.1 soon.. I will try it again... I really do think it's a driver issue... Everything else works (screen on/off), but dimming/brightness does not... Quick question, does your brightness slider bar show up under Power Options?

 

My brightness settings do not show up anywhere. Not in the charms bar, power settings, advanced power settings, nor could I even find it in the registry keys...It is like it is completely non-existent....

I even tried assigning the monitor to various INF from Lenovo's Monitor.inf download to no avail. I have absolutely tried everything.

 

Have you noticed speaker static sound on your T550 by chance? I can hear it come on with static at startup, and now I find that it is omitting static intermittently now.

 

I am using a w550s actually running win7pro. Like you I have tried everything, nothing seems to be present (even the inf files). I do not hear any static noise. I replaced the old TN panel. Waiting for the AUO B156HAN01.2 to come in and see if it works. If not then... I have no idea. This seems like such a weird problem.

 

You may need to trick the bios/vbios into thinking the old, LG panel is still present. Lenovo is notorious for blocking all sorts of non-original hardware.

Option 1 (more effort); flash 'corrected' EDID.
Sony Vaio S13 IPS Display BIOS / Brightness Issue solved (EDID)

Option 2 (easier); write your own monitor .inf.
Overriding Monitor EDIDs with an INF (Windows only)

If the hardware-block assumption is correct, then all it would need is to change the manufacturer ID from AUO to LG in the original AUO .inf. Finding the .inf would be the hard part, although you might extract the information from the registry of an AUO system and write these values in a new inf and swap in the LG id from your current registry.

 

Thank you for the suggestion. This seems to be a little over my head, can you help point me in the right direction on how I could solve this problem?

The monitor INF file is on the Lenovo website, I found it here: https://support.lenovo.com/us/en/pr...ries-laptops/thinkpad-t550/downloads/DS037801

How would I go about editing that file to enable brightness on the AUO B156HAN01.2?

 

I found that I believe the hardware ID of the monitor I am trying to use is: AUO12ED

 

Good, but you'll need the ID of the original panel as well. Try Monitor Asset Manager, this can also be used to build the EDID override inf files.