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Dealing with a panel lotto with a ThinkPad

2015 February 14
by Kirk Kosinski

Every laptop I’ve owned in the 21st century has been a ThinkPad.  Factors important to me include build quality, reliability, warranty support, and the keyboard, and all of these are typically excellent on ThinkPads.  Moreover, major components are typically made by reputable manufacturers, which helps with the reliability and (important to me) Linux compatibility.  Just as an example, the NIC on every ThinkPad I’ve owned has been from Intel, so there is no hassle at all getting it to work with Linux.  Lately, however, there have been some changes for the worse.

I recently bought a new ThinkPad T440p to replace my aging T510p.  Before that I had a T42p (and before that an A31p).  I have to admit I was never entirely satisfied with the T510p.  Although it had a high-resolution (1920×1080 / FHD) display, it was clearly a TN panel and as such the viewing angle wasn’t the best.  This is an important quality for a laptop since unlike a desktop you might want to use it in various positions.  It was a major disappointment coming from a T42p with a fantastic UXGA (1600×1200) IPS display.  In any case I eventually got used to it, but when I was recently in the market for a new laptop I was happy to see that the T-series was now advertised as having an available IPS screen.

ThinkPad T440p

ThinkPad T440p

After watching the price for a while there was finally a good sale for ThinkPads for Black Friday and Cyber Monday, so I bought a T440p.  I had a coupon code for “Up To $100 Off” from signing up for the Lenovo email newsletter which gave $60 off, and even better, on Cyber Monday Ebates had a promotion for 15% cash back from Lenovo!  That is a huge discount on an already discounted laptop.  The custom-configured T440p I ordered ended up being under $1000 with a quad-core i7-4700MQ CPU which supports VT-x (useful for running VMs using libvirt and KVM).  Note that the configuration had the minimum RAM (4GB) and the cheapest hard drive (500GB).  Instead, I ordered a 500GB SSD and 16GB RAM elsewhere for about $300 total.  Lenovo was asking over $300 to upgrade to 16GB RAM, and a 500GB SSD upgrade wasn’t even available!  Meanwhile stores like Newegg and Tiger Direct had fantastic deals for these components on Black Friday and Cyber Monday.

While I received the laptop I immediately replaced the included RAM and hard drive with the parts I bought elsewhere.  Here I noticed a nice improvement compared to my previous ThinkPads: on the T440p it is much easier to replace these components.  The bottom of the laptop is secured with a mere two screws, and removing it provides immediate access to both RAM slots and the hard drive!  The T510p has more screws and the keyboard must be removed to access one of the RAM slots.  Once that was done I installed Fedora 21.

With the installation complete I logged on to a KDE desktop and started using my shiny new laptop.  Unfortunately I quickly noticed a problem with the display: the viewing angle was simply terrible!  The main problem is a little tough to describe, but basically the brightness drop-off was very sharp instead of gradual.  On most displays if you view it at an off-center angle there is a slightly noticeable drop-off of light.  However, on this ThinkPad display, there was a distinct line separating the bright and dark areas, similar to a flashlight pointing at a white wall!  Needless to say I was disappointed, and I figured that the website must be wrong, that it was a cheap TN display and not an IPS display as advertised.

I tried to live with the laptop as-is for a week or two, but I quickly got fed up.  I contacted Lenovo customer support and explained what I thought to be the problem.  The representative helping me didn’t seem to know the difference between TN and IPS displays, but nevertheless she agreed to have a replacement laptop sent to me.  Further, she said she would include a note on the new order to request that the factory include an IPS display.

After a couple weeks I received the replacement.  I swapped in the RAM and SSD, powered it on, logged on, and to my delight the display was much better!  It wasn’t the best display I’ve seen, but at least it looked like an actual IPS display.  At this point my curiosity got to me and I really wanted to know what was causing such a difference.  Since I had Linux installed I turned to the handy edid-decode program (included in the xorg-x11-utils package on Fedora) to check the LCD panel make and model.  The full command looks like:

edid-decode /sys/class/drm/card0-eDP-1/edid

Running this on both laptops showed that they had completely different panels which weren’t even from the same manufacturer!  The model on original was LP140WF1 from LG, while the replacement has an AU Optronics B140HAN01.  Surprisingly, a bit of research showed that both really are IPS panels, but visually there is a huge difference, especially if the laptops are side-by-side with similar content showing on the display.  I decided to keep the replacement laptop and returned the original with the provided prepaid shipping label.  Kudos to Lenovo for solving the issue and at no additional cost.

After further research I came across a massive forum thread (T440s – LG or AUO Display – Lenovo Community) discussing the exact issue for the similar T440s.  I wish I had found this earlier.  One interesting (and annoying) tidbit is that you can actually just buy the AUO B140HAN01 LCD panel from eBay and install it yourself!  Not only is this significantly cheaper than than what Lenovo charges, it will also enable you to avoid dealing with a panel lottery (at least for the T440p and T440s).  I never really thought this would be possible, figuring there would be some other differences besides just the panel (e.g. cables or the bezel), but people have reported success with swapping in panels from eBay or elsewhere.  I will remember this the next time I need a new laptop (three or so years from now).

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