Acer Aspire Switch 10 (SW5-012) Backlight Removal

While I took apart the base unit of this dead Acer Aspire Switch 10 (SW5-012) tablet/laptop convertible, the main display had been left under the punishing direct heat of southern California summer sun. I don’t like fighting glue, but heat at least helps reduce their tenacious grip. I pulled out my prying tools from iFixit and plunged into the seam between gray and black plastic surrounds holding its AU Optronics B101EAN01.5 screen in place.

The double-sided adhesive foam tape was thickest around the left and right sides, gripping tightly enough that I broke the frame on both sides trying to peel them off. There were slightly less of it across the top, and surprisingly little across the bottom.

I had hoped the LCD module would pop free once the touchscreen digitizer glass had been freed from its frame, similar to how an Amazon Fire tablet was put together. But no such luck, there appears to be more adhesive involved.

Once I pushed a pick into the gap between the digitizer glass and the LCD polarizer, I realized the bad news: they have been glued together across the entire visible front surface of the screen. It’s going to take a lot of effort to separate them and I don’t see how it could possibly be worth the effort.

My objective here is the LED backlight, so just as I did for the Chromebook cracked screen and the Amazon Fire screen, I peeled back the black tape holding the LED backlight to the LCD. Starting with the bottom section to expose the integrated driver board.

I am starting to recognize the signs of a LED backlight power connection: a few connectors separate from the high-density connectors used for controlling LCD pixel data. An inductor and a diode for voltage boost conversion, and an IC controlling it all.

The black tape holding this display module together is much more difficult to remove than those encountered on previous screen backlight salvage projects. The glossy substrate is weaker than the adhesive, causing it to easily stretch and break. Now that I’ve identified the portion I cared about for my project, I pulled out a blade and cut the rest of the tape allowing me to open up this display module.

Once the backlight folded away from the LCD pixel array, I can see I’ve already cracked at least one LCD glass layer in my effort to pry it from the front digitizer glass. I’m not even going to try to salvage the polarizer filter from this one, so my blade continued its work cutting all pixel data lines to free the backlight for further examination.

Acer Aspire Switch 10 (SW5-012) Hinge

A laptop’s keyboard may be the main interface point with the user, but the hinge mechanism of a laptop computer is an often overlooked critical mechanism that can make or break the entire ownership experience. The challenge is even more profound for tablet/laptop convertibles like this Acer Aspire Switch 10 (SW5-012) since it had to detach as well. Digging into this mechanism as part of my teardown unveiled a very intricate but also extremely robust piece of mechanical engineering.

The first challenge is, of course, figuring out where to start opening it up. I pried on the back plate hoping it would pop loose. It did, sort of, in a irreversible and destructive way.

But with it open, I could tell there’s an angled metal spine to this hinge and there are probably fasteners hiding under the rubbery material that cushions the main display unit when it is attached to this base.

The two rubbery cushions were held with double sided tape. Once peeled off, each exposed two screws that helped hold the top plate in place. They’re not the only fastening mechanism, though, there were many other places where the top plate held on for its life and it did not come loose willingly. I ended up breaking it into several pieces.

Top plate removal exposed many more fasteners, several of which held the backplate.

And the remaining fasteners held the metal spine to the bottom section. This is easily the highest density of screws in this machine holding everything together, reinforcing the critical nature of this component.

I finally freed the nine-conductor pogo connector that was one of my objectives for taking this retired computer apart. There are also a few magnets that held the display module in place as a simple and elegant “Acer Smart Hinge”. They will also be salvaged for potential future fun.

And now with the hinge thoroughly taken apart, I retrieved the main module which had been baking in the sun in preparation for fighting annoying glue.

Acer Aspire Switch 10 (SW5-012) Keyboard

There were two high density circuit boards in the base of an Acer Aspire Switch 10 (SW5-012) tablet/laptop convertible. One handled general connectivity to the main display unit of the computer, and another purely focused on touchpad input. The third, while technically a circuit board as well, is less dense and is the array of switches that implement the keyboard of this machine.

Typing on this keyboard has been a good experience, at least as far as membrane keyboards go. Key travel felt good, and the scissor mechanism sturdily held actions crisp. Even though this is a thin and light (very much so for its day, and still respectably so today) convertible, it never felt flimsy. As I dig inside, I could see what gave it such a solid feel: metal structural plates and lots of mounting points.

The sheer number of mounting points make it rigid, but they are not held with removable fasteners. They are held with plastic rivets probably for cost of manufacturing, but this also meant there’s no way to nondestructively replace the keyboard module. I start by peeling the keyboard surround from the metal chassis plate. Pop, pop, pop, went those rivets as I pulled.

Once the keyboard surround was removed, I could see a magnet that I can harvest (below where the right arrow key used to be) and the remainder will become plastic landfill. The keyboard itself is held to the metal plate by even more plastic rivets, and once I pop them off to remove the keyboard the metal plate should be clean enough for general scrap metal.

Here is a closeup of the control key in the lower left corner, and the numerous gray plastic rivets holding the keyboard module in place.

I popped off the control keycap to take a closer look at the scissor mechanism on this keyboard. I imagine there are only a few major suppliers/styles for this mechanism, unless there’s a product differentiation I’m ignorant about motivating keyboard makers to custom design their own. In any case, my interest was seeing if I can cannibalize the scissor mechanism to repair a missing key on the HP Mini (110-1134CL) netbook from NUCC.

Sadly while the two scissors mechanisms are very similar to each other, they are not identical. Perhaps someone skilled with modifying watchmaker–level mechanisms can hack the pieces to fit, but that is beyond my skill level today. I’ll leave this keyboard along for now and switch focus to this computer’s robust hinge mechanism.

Acer Aspire Switch 10 (SW5-012) Base Circuitry

When I looked at the reinforcement rib network on the bottom plate I just pulled off, I saw it was not symmetric. The reason became clear when I looked at the internal circuitry of this keyboard base, those asymmetric gaps in reinforcement ribs were to make room for a circuit board and the data cables connecting it to the keyboard array.

Two large connectors dominate the center of this board, one with four conductors and another with five. These nine conductors directly connect to the nine pogo pins connecting to the main unit of this computer. If there were only four conductors I would have been tempted to see if it was direct USB, but there are nine conductors and I don’t have a good idea what might be going on.

I thought the USB hypothesis had merit when I found one of the ICs on board is a USB hub controller. It would have been a valid way to implement this keyboard base: turn the keyboard, the touchpad, and the USB port into individual USB devices connected to a common hub. But USB isn’t a protocol I’ve worked with, it works at far higher speed than any diagnostics tools I have on hand, and I’m not particularly motivated to get this running because if I did, what would I get? A keyboard and a mouse pointer device. I already have enough of those.

So I continued to merrily tear things apart looking for interesting sights as I went. The other circuit board in the base is entirely dedicated to the touchpad. The controller IC on this board is from Synaptics, a very popular supplier for touch hardware. The metal frame came apart in two separate pieces.

It works as a hinge to act against a physical button handling taps on this touchpad. I’m amused that there’s only a single button, they must correlate this button with finger positions in order to infer left or right click.

Flipping it over, I see the cosmetically perfect top surface of the touchpad.

As is typical of touchpads, that top surface is merely a façade covering a network of electrical wires that is used by the Synaptics IC to sense finger position. This is analog voodoo I don’t understand in the least, and neither do most other people, which is why companies like Acer pay Synaptics to figure out. The façade is a sticker that I could peel off to expose the circuit pattern below.

Yep, it’s an array of repeated patterns. Yep, the individual elements will help determine position of our fingers. Beyond those generalities, I have no clue. I’ve taken apart many laptop touchpad like this, and no two has used the same pattern on their circuit boards. Voodoo, I say! Thankfully, with its array of on/off switches, a keyboard is more straightforward than the analog magic of a touchpad.

Acer Aspire Switch 10 (SW5-012) Bottom Plate

The Acer Aspire Switch 10 (SW5-012) was a Windows 8 convertible tablet/laptop that easily separated into two parts. For my teardown purposes, this meant I could work on the keyboard base while the main display module is sitting in the sun to soften the glue holding it together.

When this computer is in laptop mode, the main module communicates with its keyboard base through these robust-looking pogo connectors. I’m not sure I can find a good way to reuse them, but I’m definitely trying to salvage them intact so I’d have the option in the future. It was pretty trivial to pull the top part, and extracting its counterpart from this base is my current objective.

I flipped the base over and saw several straightforward Philips screws. Laptop fasteners are usually hidden, or require an annoying esoteric tool, so this was a delightful surprise. I pulled out a screwdriver, removed (almost) all of them and pulled off the base plate.

A loud crack announced the fact that there were actually two more screws hidden under a gray strip of plastic, and pulling the base apart destroyed plastic around these hidden screws. I’m glad I have no intention of putting this thing back together into working order.

Flipping the bottom plate over, we can see the internal structure. It has a surprising complex of reinforcement ribs. Interestingly, the network is not symmetric. Not top-bottom, and not left-right, yet it speaks to a clear purpose that was not obvious from just looking at this piece.

In any case, these reinforcement ribs reminded me that this laptop, as small and thin as it was, never felt flimsy or gave the impression it would flex and break apart in my hands. Credit goes to reinforcement ribs like these and other thoughtful touches scattered throughout the design of this tablet.

There are two pieces of shiny metal that appear to serve no immediate purpose, my guess is that they are counterweights like I tend to see in other tablet/laptop convertibles. The one on the right has a thin strip of plastic as electrical insulation so it doesn’t short out the circuitry, and those circuit boards are likely the reason why reinforcement ribs are not symmetric.

Acer Aspire Switch 10 (SW5-012) Teardown

With the successful relight of a salvaged Amazon Fire tablet backlight, I’m ready to begin the final chapter of my journey with this Acer Aspire Switch 10 (SW5-012). I’m not the original owner of this machine, so it was never my day-to-day computer. It was retired when it would no longer power-up, and the charger has been lost in the time it was sitting around gathering dust. That nonworking state was how I got it as something to play with.

I diagnosed the power-up problem to a loose cable, and I worked around the lost charger with a hacked-up power connector. That was enough for me to power this system back up. I found it didn’t want to run Linux, but it could run modern Windows 10 surprisingly well. And I didn’t even have to buy another Windows license, as the Windows 8 license embedded in hardware seemed to work just fine. And I undertook some projects like removing its webcam module for security. Because no hacker on the internet can activate a webcam that’s sitting detached in a zip lock bag in another room.

But a computer that runs modern Windows 10 “surprisingly well” for its age is not the same as a computer that runs it well in a useful sense. It’s still an old computer showing its age across the board. Limited RAM, cramped storage, and most personally unsatisfying for me, a low resolution screen. The CPU is not the ill-fated Clover Trail series, but it is still quite slow and is a 32-bit only CPU cut off from modern features of 64-bit operating systems. 32-bit support has already been dropped by MacOS, Ubuntu, even Chrome OS is 64-bit only nowadays.

Finally the system failed again, with the familiar symptom of failing to power up when the power button is pressed. However, this time it was not the loose cable and I failed to find another explanation. It was then retired and I performed a partial disassembly, pulling out its mainboard for a play with a hot air rework station.

I think it is time for me to finish the teardown the rest of the way. The battery pack has already been freed and I think that two-cell lithium ion pack has a future in another project down the line. That leaves the screen, whose low resolution makes it uninteresting as a display but now with two backlight projects under my belt I’m going to see if I can salvage this backlight. Then I’ll see what else might be interesting to salvage from this machine.

Most of what’s left on this convertible laptop main unit were glued together, and I hate fighting glue which is why it halted my earlier teardown. But I have to do it if I want that backlight, so I started thinking about heating up the module to soften the glue. I used to do this with a heat gun, and with the Amazon Fire tablet I used the heated print bed of a retired 3D printer. But we’re now entering the uncomfortably hot phase of Southern California summer. So there’s no need to consume electricity: I can just set this thing out on a brick and let it warm up in the sun and turn my attention to the base section.

Amazon Fire SR043KL Backlight Layers

I took apart an Amazon Fire tablet (SR043KL) retired by cracked touch digitizer glass, seeking to salvage its display backlight and I was successful. I am fascinated by the optical behavior of modern LED backlights, even those used in products with a low price target like this tablet. After fussing with light diffusers for my Glow Flow project, I have a great deal of appreciation and respect for how evenly these backlights distributed their LED light.

I had a lot of time invested in the earlier LG laptop backlight project and was timid about fully exploring all its backlight layers, fearing that I would break something. Now that I have a smaller backlight with lower stakes, I’m going to take the layers apart and see how they act and interact with each other.

At first glance the layers for this backlight are arranged slightly differently from the LG laptop backlight. I’m too new into this field to guess what tradeoffs are involved. What I do know is that the bottom-most layer on the Fire backlight appears to be non-removable. When acting alone, I could see a dotted pattern almost like dithering.

Above this layer is a sheet of smooth matte translucent white that I would have expected to be the top layer, but here it is.

When in place, it blended the dotted pattern together into something smoother. I think this looks great as-is, but we have two more layers to make it even better.

The third layer looks wild, with the optical characteristics I associate with Fresnel lenses and lenticular lenses, but this pattern looks different and I wished I knew the right name for it so I could read more about it.

When installed, it imparted a bit of pattern along with a rainbow-like sheen.

The fourth and final layer also has that optical property, but dialed back a bit. It also has a matte top finish similar to the second layer.

When in place, we have our backlight, providing an impressively even illumination across the entire area with all light provided by a row of LEDs on just one edge.

Speaking of those LEDs, I count eighteen of them. Given that they start illuminating at around fifteen Volts, my guess is that we’re looking at three parallel strings of six LEDs each. I don’t have anything to accurately clamp current at 3*20=60mA (my bench power supply current limit is only guaranteed to be +/- 10mA) but I estimate that would be somewhere near eighteen volts which makes this barely over one watt at maximum brightness. Pretty neat!

I’m setting this aside for later use. Emily Velasco has said she has a project idea that might make use of a small backlight, so it might go to her instead. If it does, I’m sure we’ll get something really weird and cool out of it because that’s what Emily builds. But in case this backlight isn’t what she needs, I can salvage others so we have alternatives.

Amazon Fire SR043KL Display Disassembly

I have taken apart an Amazon Fire tablet (SR043KL) and retrieved the prize I sought: an intact display assembly under the cracked digitizer glass. Though presence or absence of cracks in the LCD wouldn’t have mattered for my project anyway. My objective is actually the backlight behind it.

Just like the LG laptop display I disassembled earlier, this display module is held on all edges by thin precision black tape. Peeling back the tape, I had hoped to find a LED backlight driver as I did on the laptop display, but not this time. There are a few small passive components here, but the backlight driver must be on the mainboard hidden under one of those metal shields.

Lacking an easily accessible LED driver, the next objective is to hunt for the backlight LED circuit itself. I expected them to be the largest traces relative to the other components, and I see two exposed contacts already labelled with + and -. Hmm… could it be that easy? I could do a quick test: since these two points were already exposed, soldering some wires to them were straightforward.

In order to see if the LEDs glow, I peeled back more of the tape. Slowly increasing the voltage, I started seeing a glow at around 15V. Wow, it’s really was that easy.

I have no idea how to drive this LCD array, and I have no intention to learn. My objective for today is the LED backlight. So after I peeled away all black tape around the perimeter, I sliced the high density LCD pixel data ribbon in order to separate the two parts.

There isn’t much more to be said about the LCD array. I was able to peel off the polarizer film, this time without cracking any glass, but using acetone to clean off the adhesive once again caused the film to disintegrate. That’s two strikes against acetone, I’ll have to try something else next time.

I have to put more thought into polarizer film recovery, but that’s only a mild distraction from my fascination with the backlight and its sheets of optical magic.

Amazon Fire SR043KL Screen Removal

Tearing down an Amazon Fire tablet retired due to a broken screen, I removed everything I can from the back hoping to find something that would help me release the front. This was unlikely but I held out hope…. hope that has now been dashed. There are no secret back door entrances, I have to fight the double-sided adhesive strips protecting the front door. For me, this is the least enjoyable part of electronics teardowns. There’s no clever puzzle-solving in tearing glued pieces apart, it’s just brute force messy nastiness.

I have not yet developed the knack to do this gently. If the touch digitizer glass wasn’t cracked before, I’m sure it would have cracked after I tried to pry it free. Thankfully it was already cracked, so this was merely even more cracked. And I’m thankful for the clear packing tape I applied earlier, they were able to hold most of the pieces together. If you are planning to tackle this task and wanted to see how much glue you’ll need to fight, this pictures should help.

What was my reward for all this work? The intact display screen module underneath the (now extremely cracked) touch digitizer glass. I had feared it was held by its own adhesives, but the Amazon engineers apparently decided the adhesive on touch digitizer is enough to keep both of these components in place. The screen was held by only a few thin strips of tape, and here I am thankful I removed the battery earlier as it allowed me to push from the back and pop it free.

There was a side bonus here: the tablet chassis held two small magnets. Probably for a tablet screen cover accessory, but now I want to free them. The good news is that I don’t care about preserving the tablet chassis, the bad news is that magnets are brittle and can break under stress. I misjudged how thick they were and broke one. But now I knew they were thin and only held by a strip of double-sided tape, I was able to use a thin blade and cut the other free while keeping it intact.

Once the magnets were recovered, there was nothing else I wanted from this tablet chassis frame and it will head towards landfill while I examine my prize: the LCD module.

Amazon Fire SR043KL Battery and Digitizer Cable

After I moved the mainboard more-or-less out of the way, my next objective was to remove the glued-in battery. This is not just annoying, it is potentially dangerous as lithium polymer pouch batteries like these aren’t very fond of gross physical abuse. And they have a history of protesting their displeasure with a fireworks show in your face! There were two ways forward: I could leave it alone and hope it doesn’t block anything important, or I can remove it now to uncover whatever is underneath and remove a point of volatility from the project. I decided to remove it.

The battery is pretty much surrounded on all sides, but I saw Amazon engineers left a small opening as an entry point. Here it is marked after the fact.

I didn’t see an applicable tool in my iFixit repair toolkit, so I cut apart a piece of thermoformed plastic packaging for a thin and flexible spatula to dig in. I found the bottom strip of tape, and after that I was freed, I could work my way around to free the battery from the remaining three strips. That is a total of four strips of double-sided tape, one for each edge of the battery.

Thankfully the battery did not explode in my face, but I’m not entirely sure it came out unscathed, either. There were some very definitely flexing as I pulled it freed from these four tape strips, because at the time I didn’t know exactly where they all were. Perhaps with a bit of hindsight I could free the battery while putting less stress on it, but I could at least document my findings so maybe the next person who sees this can treat their battery better.

During all of this yanking and pulling of battery removal, I flexed the touch digitizer cable one too many times and it broke. Oops. Well, at least now the mainboard has been completely freed from the case.

Earlier I thought this Kapton-covered segment might have been soldered to the board and didn’t want to pull too hard. Now that I’m no longer worried about damaging this already-damaged part, I stabbed a flat tool in there to release the bond. It turns out there was no soldering, just a piece of tenacious double-sided tape.

There were a few other trivial items accessible from the back of the tablet, including the external speaker, microphones, and switches for external buttons. I was moderately curious about these items, but I had actually hoped to find something that would help me release components on the front side of the tablet. Alas, I found nothing, which meant there’s only one thing to do: start fighting glue.

Amazon Fire SR043KL Mainboard

I’m tearing apart an Amazon Fire tablet (SR043KL) with cracked front glass, and knowing full well this low-budget device would not have been designed to be easily serviceable. After I popped off the back shell, I quickly ran into things held by adhesives of one type or another. My first focus is to see if I can free the mainboard.

The easiest item to release is the battery connector. Two screws held a reinforcement metal plate and, once those two screws were removed, the battery connector popped free easily. On the right side of the battery, I had to peel off some tape to reveal a fairly standard connector for these ubiquitous Kapton yellow flexible circuit boards. The rear facing camera connector easily popped free, but peeling it away from double-sided tape holding it in place took more effort. On the upper-right corner was an enigma. I would eventually learn this was the cable for the touch digitizer glass panel, but after I freed the small connector nothing came loose. The large yellow square was held tight and I didn’t want to pry too hard in case it was soldered underneath to something. I left this for later.

After I removed every visible screw, the mainboard remained stubbornly in place. Poking and prodding all around, I eventually noticed these two plastic claws.

Once freed from these claws, I could flip the mainboard over, still connected by the black touch digitizer cable I had yet to remove.

From here we can see metal reinforcement for the USB port and audio jack, each held down by two screws on either side of the corresponding socket. I think the red rubbery part is a cap over the microphone, next to the front-facing camera module. Springy metal fingers make contact with parts on the chassis. From left to right they are: power button (only two out of three contacts are used), the volume up/down buttons (only three out of four contacts used) and the WiFi/Bluetooth antenna. (All three contacts used.)

I had hoped there would be something interesting to see on this side of the board, but no luck. The opposite side is mostly hidden under soldered-on metal shielding, I think I need a heat plate to remove them nicely. For the moment, components on the mainboard would have to remain a mystery. So I set it aside and started working on a stubborn battery, accidentally severing the touch digitizer cable while doing so.

Amazon Fire SR043KL Teardown Begins

Encouraged by my success salvaging an useful backlight from a cracked laptop screen, I pulled out another cracked screen from my pile of retired electronics destined for teardown. Today’s subject: an Amazon Fire tablet, model SR043KL which appears to translate to the now-obsolete 7-th generation(*) of the product line.

The primary goal of these devices are to put an Amazon shopping portal into our hands, and thus the hardware cost has been subsidized in the expectation of future sales. This was made quite explicit with the bargain “With Special Offers” edition that display more ads than the standard edition. As a side effect, there is little economic incentive to repair these devices. For example, a replacement touch digitizer glass panel(*) for this tablet costs roughly $25, which is half of the normal price for a new Fire tablet(*). Which, by the way, nobody should pay $50 for because Amazon frequently puts them on sale for less.

I got this tablet from a friend who saw no reason to try to fix something when just the parts cost is at least half the cost of a replacement. And he’s not alone. The demand for repair information is so minimal that not even our trusted resource iFixit offers much help. No teardown, no repair guide, and only a few questions on the forums. For a “better than nothing” resource I poked around to find a teardown guide for a different Fire tablet to get a rough idea of what to expect.

With memories of shattered glass fresh in my mind, my first priority was to put some clear packing tape over the screen. Reducing the likelihood of flying shards of glass if it should break apart under stresses of my prying. Given the lack of serviceability typical of devices built to low price targets, I expect a lot of prying on glued-in parts.

Using trusty tools from iFixit I started digging into the seam between the bright yellow plastic and the front face black plastic.

I would not have been surprised if the colorful backshell was glued in, but thankfully it was not. Merely held by plastic clips all around the perimeter that I could pop free.

The internal volume is dominated by the battery, which is pretty typical of tablets. The battery connector is reliably held in place by two screws that I could release to unplug the battery, but the battery itself is glued in place. Over on the right just above the battery is the screen display cable, but it is held down by tenacious tape. The rear-facing camera looked like it might easily pop out, but it is also held down by tape. The black ribbon cable in the upper right is for the touch digitizer, and it is held down by tenacious double-sided tape. And I see a speaker in the lower left, which is held by… you’ll never guess…

In summary, once we pop off the back cover, there’s little else that can be done without doing something irreversible. Almost everything else would require tearing some adhesives loose. I decided to start with the system mainboard.

(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.

Investigating TI TPS61187 WLED Driver

I took apart a LG LCD panel LP133WF2(SP)(A1) hoping to salvage something useful. After I failed to salvage the polarizer film, my hope lies with the backlight module. Its diffuser had a multi-layer construction I didn’t understand but found fascinating and wanted to see it light up firsthand. And if I am to do that, I need to figure out how to send power to the backlight LEDs. When I split the panel into the display and backlight modules, I saw the backlight was connected by a ribbon cable with seven conductors. Six of them look identical, and the seventh was wider than the rest, making it a good candidate for either a common anode or a cathode. Which is it, though? For that I looked for hints on the display panel’s integrated driver board.

There were three significant-looking ICs on board. The largest is closest to the connector to the rest of the laptop and the top two lines written on it were “LG Display ANX2804”. I found no information on this chip online. In the middle of the circuit board is another IC, this one labeled “SM4037 DA1422 AMER038”. I found no information on this particular designation, either. (There exists a SM4037 from Fairview Microwave, but it is a connector and not a microchip.) That leaves the chip closest to the backlight connector as the best candidate for a LED driver, and luckily its markings of TPS 61187 match that of a Texas Instruments WLED driver. I think this is it.

Reading its publicly available datasheet reinforced it is the right result, as its “typical application” diagram shows the chip driving six parallel strings of LEDs. The schematic indicates the six strings are connected to a common anode with their own individual cathodes wired to one of six current sinks on the chip. This information is enough for me to wire up this array to my bench power supply to find the right voltage for this string and create my own LED driver circuit. But since I have the datasheet already on hand and a “I know it used to work” backlight control board, I kept reading to see if I could perhaps reuse the board as well.

It looks pretty promising. There are no handshake or control protocol involved, all the potential configurations for this chip are done via resistance values to certain pins which would be already present in this case. I think for a bare minimum setup I only need to provide a power source and a PWM signal to control brightness. I could also connect the enable pin but I think I could get away with using a pull-up resistor. And under this minimalist plan I would be ignoring the fault signals. Plus one very important lesson about its power supply I had to learn first.

LG LCD Panel Backlight Also Has Layers

I’ve got a cracked laptop LCD module by LG, model LP133WF2(SP)(A1) and I am taking it apart to see what’s inside and maybe salvage fun stuff for future projects. After I failed to learned lessons about salvage the polarizer film, my adventure continues with the backlight module. My ambition is to make it light up again as a diffused light source, hoping it’ll be more pleasant than the point light sources of individual LEDs.

I foresee a decision that I will have to make: do I work with the LEDs directly with its seven-conductor cable? Or do I try to work with the LED driver IC on the board?

But before I get that far, I wanted to examine the physical construction of this laptop LCD backlight. There wasn’t much to it at first glance, just a big flat expanse of white matte material.

I had expected a thin row of LEDs and some sort of light diffuser material, and I saw… just diffuser. The LEDs must be incredibly thin to hide under this black strip which is only about 2mm wide.

I had expected the diffuser material to be a translucent sheet of plastic. When I lifted it away from the frame, I found it’s actually composed of four layers. The top and bottom layers are close to what I had expected, they are translucent but are visibly different from each other. The surprise came in the middle two layers, which had optical properties that reminded me of a Fresnel lens but not in a concentric pattern as usually found in Fresnel lenses.

I’m ignorant on how to characterize this any more specifically, but it feels like an entire discipline of engineering that I have never known before. There are experts out there for this intersection between physics (optics) and manufacturing to mass produce these backlight elements. At some point I hope to learn the technical terms of this material so I can learn more about them. But right now this discovery makes me even more motivated to get the backlight back up and running so I can see this stuff in action. Which means it’s time to read up on that LED driver IC.

Turning to Chemistry for LCD Panel Polarizer

I thought it might be fun to salvage the polarizer from a broken laptop LCD screen, but it has put up quite a fight. I first tried direct mechanical brute force and managed to shatter the glass. Thankfully, not injuring myself doing it. When physical power doesn’t cut it, we turn to chemistry.

The risk of this approach comes from the fact the polarizer is made of plastic of unknown composition. Ideally I could find a solvent that will dissolve the adhesive and leave the plastic intact. If I was better at chemistry I might have some methodical way to find that solvent, but all I’ve got is trial-and-error. To aid in the trial-ing (and the error-ing) I have a portion of the polarizer I’ve already freed from brute force, carrying with it a layer of tacky glue. It’s enough for me to get started.

I had a rough progression of least- to most-aggressive solvents. First up to bat was 70% isopropyl alcohol, and the glue just laughed at its feeble efforts. After I let the alcohol dry, I tried WD-40, which also did nothing. I wiped up as much of it as I could before moving on to the next contestant: Goo-Gone.

Goo-Gone had some effect. It did not magically dissolve the glue as it tends to do with most other glues I come across, but it did soften this stuff somewhat, and it didn’t seem to damage the plastic. Using Goo-Gone to soften the glue, I was able to peel the sheet of polarizer free of the remaining glass and finally freed myself of the risk of puncturing some body part from thin pieces of broken glass.

However, that’s only half a victory as the glue remained stubbornly attached to the plastic making it unusable for light polarization fun. More Goo-Gone only seemed to spread it around and didn’t dissolve it. So I moved on to the next item: mineral spirits. It further softened the glue enough for me to start rubbing them off the plastic. It was a very labor intensive process, but I could start to see the shiny surface of my polarizer sheet. But I soon reached the limits of this approach as well. I started sensing uneven bumps in the surface and I couldn’t figure out what’s going on until I dried off all the mineral spirits for a look.

It appears there are multiple parts to this glue, and there is a much tougher component that clung on to the film. They were applied in lines and that explained the ridges I could feel in my fingertips while this film was damp with mineral spirit.

Finding the limits of mineral spirits for this task, I moved on to acetone a.k.a. nail polish remover. This is something I knew could melt certain plastics, as it’s used to smooth and weld plastic parts 3D-printed in ABS. However, I also knew it is not equally destructive to all plastic, as it seems to do very little (or absolutely nothing) to 3D-printed PLA parts and acetone itself sometimes comes in plastic bottles. Lacking experience in identifying plastics, I proceeded on my trial-and-error process.

The good news: using a small amount of acetone in a test corner, I found that it quickly dissolved the adhesive, turning them into soft goop that are trivial to remove. Wiping it off, I see the clear surface of polarization film with no evidence of chemical etching or erosion. I think this is the ticket!

But then I went too far by soaking the entire sheet in acetone, expecting to pull out a completely clean polarizer. When immersed in acetone, the polarizer film became brittle and cracked into little pieces. It marked the end of this experiment, but next time (I’m confident there’ll be a next time) I’ll try a few intermediate steps to see if I can find a good point on the spectrum between “few drops in a corner” and “soaking the entire sheet.”

Trying to salvage something from this screen’s LCD module was a bust, but I still have a very fascinating backlight module to play with.

Layers of Glass in LG Laptop LCD

I have a broken laptop LCD display module that I’m taking apart. It is a LG LP133WF2(SP)(A1) and it came from a Toshiba Chromebook 2 which was retired due to said cracked screen. I was able to split it into its two main components, the backlight and the display, both connected to the integrated driver circuit board. The backlight connector was something I could disconnect and reconnect, which is not something I could say for the high density connectors to the front display panel. Fortunately the screen is already cracked and nonfunctional so the majority of risk of disassembly is from broken glass.

The edge of this display module made it clear there is a complex multi-layer sandwich within.

There are at least three layers. The topmost layer is very thin and feels like plastic. The middle and bottom layers feel like glass. They don’t come apart easily, so I thought I’d try peeling the top plastic layer like a sticker. It is indeed backed by some adhesive, pretty tenacious ones at that.

I tried to keep the glass layers as flat as I could while I peeled, a difficult task with the strength of that glue which resulted in some alarming flex in the glass. I double and triple checked to make sure my eye protection is in place while peeling. After several centimeters of progress, scary bending and all, I felt a “pop” as the flexing freed whatever had held the middle and bottom glass layers together around their edges. Once this corner popped free, it was trivial to travel around all edges to peel the two glass layers apart.

It was damp between these two layers, presumably a thin layer of the “liquid” in Liquid Crystal Display (LCD). It was easily absorbed by a single sheet of paper towel, and its oily residue cleaned up nicely with 70% isopropyl alcohol. As far as I know, this is not a toxic material and I had not just cut years off my life, but I went and washed my hands before proceeding.

The bottom layer is where the original crack had lived, and these cracks had gotten worse due to the recent flexing. I don’t see anything of interest in this layer so I set it aside for safe disposal.

The two glass layers each had a grating that can be barely felt with my fingertips. They are also visible if I shined light through each layer. They are orthogonal to each other which would make sense if one set controlled horizontal pixels and the other controlled vertical pixels. Also, once the two glass layers separated, I was able to confirm the passive polarization filter (one of the objectives for salvaging) is the flexible sheet of plastic I had been tugging on. I resumed peeling that layer but didn’t get much further. Now that I only have one glass layer instead of two, it shattered under stress.

Even though I expected this as a potential (likely, even) outcome, it was still a surprise when things finally let go. Three cheers for eye protection! I picked out a few tiny shards of glass from my fingertips, but none of them found a blood vessel so there was no bleeding. And I think I managed to collect all the pieces scattered around the table. I had thought this would be a minor setback and I could continue peeling but just with smaller pieces of glass, but I was wrong. I don’t know my glass properties very well, but something happened here to change the mechanical properties of the glass. Once the first break happened, it has almost no strength at all. Continuing to peel — even at a lower force — causes new breaks. Brute strength will take me no further. And when brute strength fails, I turn to chemistry.

LCD Panel Driver Circuit Board

I’m taking apart a broken laptop LCD panel, a LG LP133WF2(SP)(A1) from a Toshiba Chromebook 2. I started with the very fancy tape surrounding the edges. Once the tape was gone, its top edge started unfolding into two parts. But they’re still held together on the bottom edge with the integrated driver board for this display. So I should figure out what that’s about before trying to completely separate the two parts.

The front side of this board had three sets of extremely high density connectors to carry signal for all 1920×1080 pixels on this module.

The back side of this board had all of the integrated circuits and a lower density connector for the backlight.

A single cable carried both power and data from the laptop mainboard. The chip closest to that connector was the largest IC on this board and probably mastermind in charge of this operation.

A search for “LG ANX2804” came up empty, which is not a huge surprise for a chip designed and built by LG for internal consumption by their display division. There’s no reason for them to distribute specifications or datasheets. On the other side of the board we see a connector for the backlight. The connector has nine pins, but in the ribbon we see six thin wires plus a wider seventh wire. This wider wire consumes two of the nine pins, making it a good candidate for either a common anode or cathode for LEDs. This left one pin in the connector seemingly unused.

I had expected just two wires for a simple string of LEDs, but the backlight is evidently more complicated than that. I’m optimistic I can get this figured out because the IC closest to this connector is clearly marked as a TPS 61187 by Texas Instruments, and I hope the information available online will help me sort it out later.

Returning to the front of this board, these high density data connectors are fascinating but I don’t understand everything that’s going on here.

I count somewhere between four and five contacts within a millimeter. This is definitely beyond my soldering skill, but they aren’t soldered anyway. Whatever this type of connection is, it is clearly single use. Once I detach it (it peeled off like tape) there’s no way for me to reattach it. I see nothing to help me align the connector. I’m also curious about the fact the copper contacts area is wider than what we see actually used. I’m sure it’s a provision for something but I don’t know what. For today it doesn’t matter, as the screen is already cracked and nonfunctional so I lose nothing by peeling them off before I explore its intricate layers of glass.

LG LCD Panel LP133WF2(SP)(A1) Teardown

After I checked the USB OTG reader off my teardown to-do list, I decided to continue ignoring what I had originally planned to do and continued tearing down another item that’s been sitting on my teardown to-do list: a broken LG LCD panel LP133WF2(SP)(A1). It was the original screen in a Toshiba Chromebook 2 (CB35-B3340) which I received in a broken state with the screen cracked. I revived the Chromebook with a secondhand replacement screen, and I set the original cracked screen with the intent of eventually taking it apart to see what I can see. “Eventually” is now.

Out of all the retired screens in my hardware pile, this was the most inviting for a teardown due to its construction. The ever-going quest for lighter and thinner electronics meant this screen wasn’t as stout as screens I’ve removed from older laptops. I noticed how flexible it was and it made me nervous while handling it. Most of the old panels I’ve handled felt roughly as rigid as a thick plastic credit card, this display felt more like a cardboard business card. I’m sure the lack of structure contributed to why the screen was cracked.

The primary objective of this exercise is curiosity. I just wanted to see how far I could disassemble it. The secondary objective is to see if I can salvage anything interesting. While the display itself is cracked and could no longer display data, the backlight was still lit and it would be great if I could salvage an illumination panel. And due to how LCDs work, I know there are polarization filters somewhere in its sandwich of layers. I just didn’t know if it’s practical to separate it from the rest of the display.

The primary concern in this exercise is safety. The aforementioned quest for light weight meant every layer in this sandwich will be as thin as it can possibly be, including the sheets of glass. And since the screen is visibly cracked, we already know this activity will involve shards of broken glass. I will be wearing eye protection at all times. I had also thought I would wear gloves to protect my fingertips, but I don’t have the right types for this work. All the gloves I have are either too bulky (can’t work with fine electronics in gardening gloves) or too thin to offer protection (glass shards easily slice through nitrile.) I resigned to keeping a box of band-aid nearby.

All that said, time to get to work: around the metal frame this panel is surrounded by a thin black material that contributes nothing to structure. It’s basically tape. Cut to precise dimensions and applied with the accuracy of automated assembly robots, but it’s adhesive-backed plastic sheets so: tape.

The adhesive is quite tenacious and it did not release cleanly. Once peeled, the top edge of the LCD array could separate from the backlight. The diagonal crack is vaguely visible through the silvered mirror back of the LCD.

This is a good start, but I can’t pull them apart yet. Right now they’re both connected to this panel’s integrated driver circuit board.

Rosewill USB OTG Memory Card Reader (RHBM-100-U2) Teardown

I got this thing from a “Does Not Work” box intending to do a teardown. Since it’s so small, I thought it would be fun and quick, but I kept putting it off. It’s been sitting adjacent to my workbench through several reorganizations and cleanups, and I kept moving it from one place to another. Today I was about to move it again when I decided: No more. I have other things I need to do, but I’m putting them on pause for this thing. Today is the day.

Based on all the slots on one side, this is clearly a multi-format flash media reader/writer. The other end was a little more interesting, as it is a USB micro-B plug instead of the usual socket. The presence of the plug implies this was designed for use with USB OTG devices such as an Android phone, allowing them to read and write flash cards. Aside from a few labels for the various types of flash media, there was only the “Rosewill” brand logo. I found no model number or serial number printed on the enclosure. Searching for “Rosewill USB OTG” retrieved information on many products. The closest match based on pictures is the RHBM-100-U2.

There was a visible seam around the faceplate full of memory slots. The remainder of the enclosure appeared seamless. The lack of fasteners indicate this faceplate is glued in place. Using pliers, I was able to get a bite out of the enclosure to use as starting point. Not elegant, but I’m going for speed in this teardown and elegance be damned.

The bite allowed my pliers to get a firm grip on the faceplate and peel all around the perimeter. After that, I could pull the faceplate free.

Once the faceplate was removed, a firm push on the USB micro-B plug popped the final few glue points free and I could slide out the PCB. As expected, it was relatively simple dominated by surface mount flash media connectors.

Aside from those media connectors, one side was dominated by small passives.

The other side had one IC clearly more sophisticated than anything else on the device. The only other unexpected item is the black goo on the USB micro-B plug. I have no idea why that is there.

Searching on “GLB23” didn’t get me anywhere, but “GL823” got a likely hit with Genesys Logic. It is advertised as a single-chip solution for implement a multi-format USB media card reader, which is a perfect match for the device at hand. I didn’t bother downloading its datasheet, but I wouldn’t be surprised if this device basically followed the reference design.

Years after I picked this up, intending for a quick teardown, I finally did it. It no longer needs to occupy space on my workbench and I can move on with my life.

Western Digital My Book 1TB (WDBACW0010HBK-01) Teardown

I took apart an external USB 2.0 hard drive I had formerly used for MacOS Time Machine, but haven’t touched in years. It was the second of three external drives under two terabytes that I had gathering dust. The third and final drive to be disassembled in this work session was used for a similar purpose: the Windows Backup tool that (as far as I can recall) was introduced in Windows 8. Now it will serve that role again, sort of, by becoming part of my fault-tolerant ZFS RAIDZ2 storage array running under TrueNAS. Which does not support USB external drives, so I am removing the bare drive within for its SATA connection.

Like the other two drives, this one lacked external fasteners and had to be taken apart by prying at its seams to release plastic clips. (Not all of the clips survived the process.)

The geometry was confusing to me at first, but following the seams (and releasing clips) made it clear this enclosure was made of two C-shaped pieces that are orthogonal to each other. I thought it was a creative way to approach the problem.

I was also happy to see that the cooling vents on this drive was more likely to be useful than the other two, since the drive is actually exposed to the airflow and it is designed to stand on its edge so warm air can naturally escape by convection. There is no cooling fan, and none was expected.

Like the other two drives, there’s a surface mounted indicator LED on the circuit board. To carry its light to the front façade, there’s an intricately curved light pipe. It might look like a flexible piece of clear plastic in the picture but it is actually rigid. I was a little sad to see that, because its precision fixed curvature means there’s almost no chance I can find a way to reuse it.

Two circuit boards are visible here. The duller green board is the actual hard drive controller circuit, the brighter green board is the USB3 adapter board converting it to an external drive. My goal is to remove the bright green board to expose the bare drive’s SATA interface so I could install it in my TrueNAS server. It was quite stoutly attached! On the other two drives, once the internals were exposed I could easily pull the drive loose from the adapter board. This board was rigidly fastened to the drive with two screws, including this one that took me an embarrassingly long time to find. On the upside, this rigidly fastened metal reinforcement meant the USB3 port is the strongest I’ve seen by far. Another neat feature visible here is a power button, a feature I don’t often see on external drives.

This assembly was mounted inside the external case with some very custom shaped pieces of rubber for vibration isolation. Like the light pipe, I doubt I would be able to find a use for these pieces elsewhere. But that’s fine, the main objective was to retrieve the SATA HDD within this enclosure and that was successful.

This is enough hard drive “shucking” for one work session. I have more retired drives (two terabytes and larger) awaiting disassembly, but I think I have enough to satisfy my TrueNAS array replacement needs for the near future.