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.

 

Monitor
Windows description...... ThinkPad Display 1920x1080
Manufacturer............. Lenovo
Plug and Play ID......... LEN40B4
Data string.............. N156HGE-EA2
Serial number............ n/a
Manufacture date......... 2013, ISO week 40
Filter driver............ Monitor
-------------------------
EDID revision............ 1.4
Input signal type........ Digital (DisplayPort)
Color bit depth.......... 6 bits per primary color
Color encoding formats... RGB 4:4:4, YCrCb 4:4:4
Screen size.............. 340 x 190 mm (15.3 in)
Power management......... Standby, Suspend, Active off/sleep
Extension blocs.......... None
-------------------------
DDC/CI................... n/a

LEN40B4 is the ID of the old one

 

Here are screenshots of what I found with Monitor Asset Manager

 

Can you see the new LG as well or is this the only monitor present? And what is the exact version of the new LP156WF4? There's four characters after that, something like SL**/SP**.

Did some research; even on native systems brightness control of this AUO is only available after installing the latest Intel HD Graphics driver, might try that, if you haven't already. Run DDU first.

 

I'm not sure, I have a different original panel on mine. The original one in mine was actually made by AUO as well, but it is a 1366x768 panel as opposed to the stock 1920x1080 panel. The original HD panel in mine is the hardware ID AUOe5EC. When I replaced it with the better panel, that hardware ID is AUO12ED.

I have tried uninstalling the display driver. I have completely removed it several times, and then reinstalled the latest Intel HD drivers. I have also tried running off of the integrated Windows Display Adapter, but to no avail.

Furthermore, if I remove this panel and stick the original back in, the brightness controls show up and work. It's very strange, and almost inclines me to believe there is some sort of hardware blacklist that is disabling this feature somehow.

 

https://msdn.microsoft.com/en-us/library/windows/hardware/jj133967(v=vs.85).aspx

"For example, during initialization the monitor driver queries the Windows Display Driver Model (WDDM) driver for its brightness query interface and device driver interface (DDI) support" <--- so yah, we have to replace the .inf file of the previous working TN panel with the ID for the new one and try to trick the bios.

 

Worth a try, AW EDID Editor can help with that. It can import current registry values, edit these and write back a .dat which Monitor Asset Manager can use to create the inf.

Spoiler: AW EDID Editor

Alternatively, since the new panel is listed in the registry already; simply overwriting the manufacturer/model id in the new panel's settings ought to do that (no .inf required then). So the new/1080p, only with the headers of the old/768p.

Spoiler: monitor info, registry

Seems you can't do that while it's in use, so swap in old panel, edit id's and replace with new panel ought to rule out a hardware block.

Right, both eDP/2-lane, so no new cable was required ... Pinout of the lcd connectors on the B156HAN01.2 and N156HGE-EA2 are identical too, so ... black-/whitelist seems more and more likely.

 

Ok, so I put the original panel back in and went to the registry editor. However, it will not let me change the values. For example, when I go to edit the hardware ID for the new panel and try to put in the hardware ID of the working panel, it gives me the error message in the screenshot. It also does this for attempting to change any attributes like the manufacturer. AUO12ED is the panel I want to work, LEN4080 is the original panel in the registry (which was the installed panel this time, while I was trying to edit the one I want to use with the original headers).

Again, comically, my brightness works with this crappy screen back in lol.

 

Option B; try this forced during boot-time. Export those keys to a .reg and edit it with notepad to the desired values. Save it as something like in c:\monitor.reg and write ' regedit /s monitor.reg' in the autoexec.bat.

 

Ok, so I actually tinkered around with it and got it to take the registry changes (my permissions weren't set correctly).
I changed the Hardware ID and manufacturer for all 3 to the same entries as that of the original panel. Restarted, no dice...

 

Darn ... there goes that theory. One of those AUO's is still listed in Monitor Asset Manager as [Registry-Active], correct?

If it's not a block, it might simply be that an IPS panels requires a physically different brightness control than the TN did. Since the new panel's timings and resolutions are written to the registry and these are used (no 1080p otherwise), then the motherboard's brightness control may not properly sync with an IPS. It's a long shot and it'll probably result in a black screen, but ... you could overwrite not just the id's, but the full edid string as well.

Spoiler: registry edid string

Last, dirty resort is a potentiometer spliced in-between pin/wire #23.

Spoiler: connector pinout, edp, 2-lane, 30-pin

 

Yes, one of them is listed as [Registry-Active]. I can't see Lenovo actually going through this much trouble with the LCD panels, to that end I have never in my life experienced this sort of issue with replacing an LCD....Everything works with it except this darn brightness....

If it were a matter of syncing with the motherboard, wouldn't there be other significant problems observed as well? The other part of this is that these motherboards support varying LCD's from the manufacturer, including TN FHD panels and 3K IPS panels. I can't see it being this significant a problem. Perhaps I should lean more towards returning the laptop?

 

Two questions:

a) Are you able to control the brightness while looking at BIOS page, before the system is booted into the OS?

b) Have you tried booting a "live" Linux media and verifying whether the brightness is controllable there?

Good luck.

 

What does this mean?sorry not linux-savvy

 

Boot a "live" Linux media such as USB or CD/DVD. Your favourite search engine will teach you how to create one.

Once the system boots into the OS, check and verify whether the brightness controls work.

Good luck.

 

I'll be...I booted to BIOS and the brightness controls do work in there. I haven't tried Linux media but I have a bootable Ubuntu stick I can try. Strange it works in BIOS but not in the Windows OS, I'm assuming that there is no hardware block on various LCD panels in this case.

 

There you go...

I'd be presuming the same thing.

Good luck.

 

I don't understand what else it could be other than Lenovo drivers/Intel drivers problems. Is this even an issue that can be remedied by an end user?

 

Just a thought, have you tried connecting to an external monitor then adjusting/saving the panel ID of the internal LCD?

 

My instinct would be to wipe the drive and re-install the OS from scratch. Having said that, I don't have a "scientific" answer to offer you.

Good luck.

 

Doesn't work, tried that on my end... clean install with Win7Pro on a new HD... still the same problem... if brightness works in bios... but not on windows... it has to be a windows registry issue right? what else could it be?

 

I too just tried a clean install of Windows 8.1, same result. So now we know this is an issue with both Win7Pro and Win8. If it is working in BIOS, it has to be something to do with Windows drivers and/or Lenovo drivers. Perhaps I will try a different panel, I've ordered an LP156WH4(sp)(h3)...will see if that panel works. I'm not sure what else it could be.

 

I hope you guys can figure this out because I'd like to swap out my x768 panel on my T550. Excellent unit besides the screen.

 

Someone posted on another thread that their stock 3k display does not have brightness controls (no function controls or windows controls) with the w550s

 

If this piece of information is correct, then I'm absolutely stunned that anyone in their right mind - even Lenovo - would allow such a product to "hit the shelves".

 

Yeah, that's sketchy if that's true, if it's true it would lead me to believe lenovo will make some kind of update to fix the problem. My last resort solution was to buy an OEM model 3K panel which is what I should have ordered the computer with to begin with. That said in all of the reviews, lots of them with the t550 had the 3k panel and none of them said anything about the brightness controls not working.

 

I'm still curious - now more than ever - to find out what happens when you do boot a *nix of any kind...

 

I booted Linux Mint Cinnamon, noticed no control of any brightness settings in that environment....

 

Working on it...but it hasn't looked good so far. It's a shame too the potential that this machine had, if something like this were to ruin an otherwise excellent machine. I have debated on whether or not to return it or just "live" with the max brightness until some other fix can be implemented (hopefully) in the future.

 

just received my unit... will update soon.

 

replaced the stock 1080p TN panel with the B156HAN01.2.

1) brightness controls work in bios
2) brightness controls do not work in windows nor does it appear in "power options" under window's setting
3) attempted to copy over the .inf generated by moninfo from the old panel and installed it ... caused a blue screen...

so.. don't know what else to do...

Kenstang - how did you edit the registry files?

 

You can open the location through Monitor Asset Manager. Select view, then registry. It will take you to the specific location of the monitor you have selected. To edit the registry in Windows 8, you will need to change the ownership of the folder with the key and subkeys you want to edit. After you change ownership, enable full control for the account you are using to edit it. Otherwise, Windows won't let you do it.

Make sure to back up your registry

As for a color profile, you can try this: http://www.notebookcheck.net/uploads/tx_nbc2/P505_01.icm

 

Registry changes did nothing and did not stay... kept refreshing the modelid back to the old...

 

There is a program that I used many moons ago to flash the info in the actual EDID, and not within the registry. Worked in XP only, from what I recall. It was called Power Strip, and the paid version was necessary in order for the operation to be performed. An external monitor was also required.

Apologies for not being more specific, but it's been a long time...

Good luck.

 

I don't know anymore. Weird that brightness control only works in Bios and not Windows (clean install with all the video/display drivers).

 

I know...it is very weird. There is seemingly no plausible solution right now, and it is ruining an otherwise excellent machine. This should not be an issue in any way, something as simple as replacing an LCD panel...It didn't work in Linux either when I booted into it...

 

Btw, anyone want to trade their 3 cell for my 6 cell battery? lol

 

This thread definitely has me questioning if I should upgrade my t540p with the lg ips display. One thing I want to note is that when I did a fresh install of Windows 10 Enterprise beta on the t540p, I lost brightness controls with the stock 768p monitor.

Definitely some kind of windows issue.

 

Did some research and it appears there are two methods to drive the PWM backlight control (defined by the embedded IC); direct PWM control and SMBus.

Spoiler: TI TPS61195 - PWM control IC

If the AUO uses the latter method this might explain it works in the bios yet not in the os; it would need the correct driver, whereas direct pwm works out-of-the-box. The Clevo P651SG, P751ZM and Acer Aspire V5-573G use the same panel, didn't find drivers for the Asus, but the Clevo's can be found on the mysn/XMG site. Look for the P505/U505 " Hotkey" drivers.

If that didn't work it's probably direct pwm control and then there could be another issue; the LG uses 1,000Hz for its highest PWM frequency, whereas the AUO's is 10,000Hz.

Spoiler: AUO B156HAN01.2 and LG LP156WF4-SPB1, PWM control

This is much easier on they eyes, so a nice improvement. Though if the external variable resistor cannot accommodate the different required range then the pwm control might work, but it'll have zero effect.

One last resort would be to take direct, current control over the pwm signal on wire #23. This is a bit iffy; the low voltage, high impedance would need a very low value trimmer; something like this one should do. Upside is that it's also very puny, so it'll fit nicely below the power-button board; just need to to drill a small hole to access the tuner.

 

I appreciate the help you have put into doing the research. I will give the drivers a go and see what results I end up with.

 

Ok so I tried both the P505 and U505 drivers, neither worked

On another note, being that other panels are offered on this model T550, I wonder if any of the alternate panels share different characteristics? They offer a TN FHD and a 3k IPS panel, do they have similar frequencies? B156HTN03.0 is the stock FHD panel, not sure though of what the other panels are, although I know the 3k one is a Panasonic panel.