Repairing an Android Tablet
callum.snowden 4 Oct 2022
Disassembling a Google Pixel C tablet to attempt a screen repair.
My colleague Andrew has recently written articles surrounding the right-to-repair movement and what it entails, and some of the tools necessary to arm yourself with to be able to repair your own devices.
As the climate crisis of the world rages on, being able to repair our own devices instead of recycling them becomes ever more pertinent. Not only that, but as consumers, we have all paid good money for the devices we own, so being able to repair them ourselves makes sense from a fiscal point-of-view — alongside the added "feel good" benefit of having successfully repaired a device.
Inspired by reading those articles I decided to attempt a repair of a Google Pixel C tablet (a late-2015 device with an Nvidia Tegra X1 system-on-chip paired with 3GB RAM and 32/64GB flash) that was handed to me under the guise of "if you can repair it, you can have it".
Before I could start with a diagnosis we needed to take a look at tools. As the trend with mobile devices has been to reduce device thickness as much as possible, traditional fastening methods such as screws have (mostly) given way to adhesives including glue and double-sided tapes making repair more awkward and fraught with the risk of displays cracking or being damaged.
Often, application of heat helps loosen adhesives so we picked up an RS Pro hot air station (124-4133)
that is capable of temperature control from 100 to 400°C with adjustable airflow. This is an affordable entry-level station that includes a number of different nozzles that are suited to a variety of different tasks.
To accompany the hot air station in our repair process we selected a toolkit (124-9873)
that contains 88 tools suited to repairing mobile devices. This includes an assortment of screwdriver bits, suction cups (intended to help remove device screens), two spudgers for prying, six guitar pick-alike tools for careful prying and tape slicing, a number of tweezers and a magnetic pad for holding screws in place when removed — small screws have a penchant for launching themselves off never to be found again, so this is particularly helpful. Also included within the kit is an antistatic wristband that should be worn when repairing devices as often the components that lie within are quite ESD sensitive — without suitable grounding unseen damage could be caused that could then result in a device dying immediately or sooner than usual.
A roll of double-sided tape (436-2807)
was also acquired to be able to replace the original screen adhesive should the repair prove successful. In case any internal cables needed to be taped down, a roll of polyimide tape (commonly called kapton tape) was sourced.
Diagnosing the Patient
As this device was previously owned by my father I had first-hand experience of the issues which initially manifested as the screen taking a longer than usual amount of time to turn on when woken from sleep.
This issue progressively got worse until the screen would not come on at all, at which point the device was handed over. Scouring the internet showed lots of people also experiencing the same issue after a number of years of usage, with some suggested fixes, so all hope was not lost about being able to repair the tablet.
Initially, it appeared that the tablet was completely dead in the water and with only the rear light bar illuminating, but on closer inspection, the display itself was receiving data and displaying an image — seemingly the backlight had died.
Various posts online suggest that opening up the tablet itself and reseating the display FFC connector, combined with some additional support material to ensure good contact, is enough to resurrect the device.
Without anything to lose, I opted to give this a go. The first port of call I tend to look at when repairing a device like a tablet or phone is iFixit, as their tutorials and teardowns tend to be well written, thorough and easy to follow.
The iFixit teardown had notes to be cautious of both the display FFC, as well as the camera FFC as the front-facing camera is fastened to the screen rather than the chassis.
Attempting the Repair
The first step was to gain entry to the tablet. I started to apply hot air at the lowest temperature the station would go to in an attempt to reduce the risk of LCD damage. With a corner of the display sufficiently warmed a suction cup was stuck on top and carefully pulled to create a small gap in which a "guitar pick" could be inserted.
With the pick in place, I slowly began to move around the display edges warming them with the heat gun. As I moved around, more picks were inserted and carefully slid up and down the edges to cut the adhesive tape holding the display in place.
Unfortunately, in one corner of the display, a pick was inserted too far which began to separate the LCD from the digitiser — this caused some bubbling where the Liquid Optically Clear Adhesive (LOCA, used to bond an LCD panel to a glass digitiser to form a display assembly) was being forced apart. Unsure of whether this would cause functionality issues, I pushed on regardless, taking more care not to insert a pick so far.
Eventually, the display detached and could be carefully lifted, taking care not to sever the cables.
Before disconnecting the LCD cables I wanted to disconnect the battery to ensure the tablet was powered down, but this proved trickier than expected due to a strong piece of plastic tape holding the battery connector down. Some prising with a spudger resulted in the plastic tape snapping and allowing the battery connector to disconnect vertically — it seems to be the norm that battery connectors in tablets and mobile devices plug in vertically, as opposed to the horizontal action that FFC connectors have.
With the screen removed any leftover adhesive tape was cleaned off, and the contacts on both display FFC and connector were checked for debris or signs of wear and damage.
As no damage was found the display was reconnected, and a strip of kapton tape placed over the top to apply some additional pressure to the flex as well as retention in the connector.
The battery was then reconnected, and the screen placed over the tablet. With bated breath, the power button was held until the tablet displayed the light bar indicating it was powering up, and… sadly I was met with nothing on the screen.
Even after gently wiggling the display FFC with the tablet powered on the screen remained blank and lifeless, and for good measure, some more charge was put into the battery which didn't help.
To be 100% sure I shined a torch through the front of the screen and was still met with nothing, so unfortunately this device is now consigned to my e-waste pile to be recycled.
In this article, we've had a think about why devices should be repaired and taken a look at some of the tools necessary to repair modern devices. We then embarked on a journey of repairing our own device, utilising resources such as iFixit to guide us through the process.
The right to repair movement is one we should all attempt to embrace, whether that's attempting repairs yourself or by utilising the services of local hackspaces and repair cafes — not only for the good of your own wallet, but also for the good of the Earth with the current climate crisis.
Even though ultimately the repair was not successful, hopefully, the experiences shared will prove useful to others who are considering carrying out similar repairs. The disassembly techniques, and tools and caution required, will be much the same for other modern electronics.
callum.snowden star_borderFollow
Engineer of mechanical and electronic things by day, and a designer of rather amusing, rather terrible electric "vehicles" by night.