Introduction

Three years ago my beloved Dell XPS 9370 laptops display back light suddenly stopped working. In this post i’ll describe how i managed to bring it back, and my struggles throughout

So, where to start

So, one day i find my laptops back light broken, it just wouldn’t turn on. I have a good understanding of electronics, so my first through was just that something software wise had crashed, so i of course started by rebooting the computer. Nothing. Now i started to panic. The laptop was just beyond warranty, and I was a broke university student and just didn’t have the money to go out and buy a new laptop.

Step two is always to Google. Have someone ells had this problem and figured out how to resolve the issue. This led me to find posts on Dells forum and Reddit with this exact problem

‎Dell XPS 13 9370 - Display backlight not working | DELL Technologies

Dell XPS 13 9370 - Really dark screen | Reddit

On Reddit they suggested different approaches, but nothing seemed to work on my laptop. On Dells site, they just told them to contact Dell…

Ok, so what to do to make it work fast.

I just bought an external screen that worked with only USB C, specifically the ASUS ZenScreen MB166C . And yea, that worked, but damn i looked like a fool with a screen over a screen.

This was pretty much my approach the rest of my time at uni. After i was done with my studies, i had a little more time, so i though i would give it another go.

Another try

The laptop was still in perfect condition (other than the screen issue) and i though i was a terrible waste if i just tossed the pc because of this.

I was painfully aware that this was a hardware issue, so the first thing i thought would help was a new screen. In my mind it made sense that they of course would place the back light circuit in the screen for easy repair ability. So i went on Aliexpress. Found a screen that matched my specs. Wrote with the seller to make sure it was the right one and made an order for this screen After i received the order, i got to work and replaced the screen with the new one, hoping it would fix the issue. It did not.

The new screen worked perfectly fine, but the back light issue was still present. That sucked bad. I had just thrown $200 into a solution that did not work. So i doubled down. I bought a Hot Air Desoldering Station and while waiting for it to arrive, i started to research.

I was able to find the schematics for the laptop on the badcaps forum which was a huge win. These schematics are locked down tight, and only release to the repair shops. But now i had another issue. My non existing patience to go through the entire schematic.

But we live in the age of ‘AI’ so i opened up Claude, and gave it the schematic, and described my issue. It gave me back what it thought was the issue. An IC that maybe had failed.

[!NOTE] Primary suspect: U22 (AP22850SH8-7_W-DFN2020-8) This is the load switch IC that controls power to the backlight. It’s located on Sheet 37 and has built-in overcurrent protection (which acts like a self-resetting fuse). If this chip has failed:

It won’t provide +INV_PWR_SRC voltage The backlight won’t illuminate regardless of screen replacement

Testing procedure:

Check for +INV_PWR_SRC voltage at the eDP connector (should be battery voltage ~7.4V when enabled) Check for EN_INVPWR signal (high = enabled) If EN_INVPWR is present but +INV_PWR_SRC is missing, U22 has failed

This gave me hope, that there was a solution. I found my multimeter and messured the connections, and to my great surprise, there was no voltage on the pins.

You can see the label U22, where the IC is.

I then ordered a couple of the IC AP22850SH8-7 on lcsc.com Now we were cooking. After they arrived, i just stared at the size of the IC. It’s package is W-DFN2020-8, which means its size is 2mm by 2mm… ITS TINY.

Ok, no panic. I convinced myself that it was doable.

I managed to remove the old one, and a couple of tries later, i was able to solder the new one on. Power on, moment of truth.

IT WORKED! I had brought my beloved laptop back to life.

Here is a tired but proud and happy Lauge celebrating the success

So, in the end it all ended happily. But, at what cost.

Reflection

Why the fuck is repairing so hard in 2026??? Why are so much ewaste thrown away? Because it breaks easily (maybe too easily..) and its difficult for the average person to repair, and its too time consuming for a repair shop to fix difficult problems.

Here is the aftermath of the repair

I find this to be the most infuriating part about working with electronics

• The design is not made to be easily repaired.
• Replacement parts are not sold by the companies making the electronics.
• Guides are not available from the manufacturer.
• Schematics are hidden away and only found by users sharing them on the web
• Special knowledge and tools are needed to even be able to repair simple issues.

This should not be accepted.

My wish for the world of tomorrow, is that we work to make our stuff last much much longer.