Author: Roger Cheng

Roger Cheng

MODCASE MASS (Free Edition) 3D Printed Mini-ITX Case

A nifty-looking 3D-printed computer case came across my attention recently: Modular Attached Storage Stack (MASS) by MODCASE. Just like the name says, it is a modular stackable system for building data storage servers, featuring a core module for the motherboard and PSU and however many hard drive modules you want. There is a paid version with additional features but I wanted to try the free version first as it should be sufficient for my immediate needs. I downloaded the 3D printer STL data files from Printables.com, and dusted off my 3D printer for a go.

My objective is to give the guts of my decommissioned Luggable PC Mark II a decent home. The Mini-ITX motherboard and compact SFF power supply had been taking up a full-sized tower case and that is silly. Especially since it doesn’t have any storage drives: at the moment it is a Proxmox server and all I need is the M.2 NVMe SSD on the motherboard. So why am I printing a storage server case? Because (1) I think this will become a storage server in the future and, (2) for today I can print just MASS core without the storage modules.

Printing MASS modules proved to be challenging due to many sharp right-angle corners that want to lift as PETG cooled. I know my print bed adhesion is not perfectly dialed in and MASS rubbed it in my face with multiple failed prints.

Once printed and assembled, though, MASS core was impressively compact. Here is a size comparison against a Cooler Master Mini-ITX case. For my current purpose I did not need the externally accessible 5.25″ drive capability or three internal 3.5″ drive bays, nor do I need to accommodate a full-sized ATX power supply. Trading off those capabilities meant MASS has roughly 1/3 of the volume. And this is with a fairly thick and robust design, as it may potentially be asked to support the weight of multiple drive modules. I think 1/4 volume is achievable if the case doesn’t need to be as robust.

Since MASS is a 3D-printed case, we are on our own to supply all components that typically come with a commercial computer case. Mounting screws and nuts, external USB ports, etc. A critical component is a normally-open momentary-close power switch. I enlarged the provisioned buttonhole to fit an illuminated button I salvaged from a dead Form Labs Form 1+.

The power supply side of my build is pretty packed with power cables. There would be less crowding if a power supply with modular cable system is used instead.

The mainboard side, however, is unobstructed which is great for cooling. It would also ease routing SATA cables necessary to turn this into a storage server. This particular motherboard has six SATA ports, but Mini-ITX boards typically have fewer.

For more storage capability, there might be enough room for a low-profile HBA (Host-Based Adapter) card from a vendor like Art of Server. But without a way to screw the metal back plate down, it would not be held securely. This is one reason to step up to the premium version of MASS as it has explicit provision for installing a low-profile PCIe card.

MASS side panels are held in place with stumps that clip into the case. These stumps are liable to break off if layer adhesion is less than perfect. Apparently mine are not!

I have put my MASS core into service and it has worked well so far. If somebody has a 3D printer that can avoid my issues with corner lifting or layer adhesion, MASS is a great choice. If their printer isn’t perfectly dialed in, I would warn to expect some level of print frustration. I probably won’t print MASS again but that’s no fault of the design. I’m just more likely to take a stab at designing my own case reflecting my own priorities.

Roger Cheng

Test Run of Quest 2 and Eyeglasses

OK so sticking some googly eyes on my Quest 2 wasn’t a serious solution to any problem, but there was another aspect of Apple Vision Pro I found interesting: they didn’t make any allowances for eyeglasses. Users need to have perfect vision, or wear contacts, or order lens inserts that clip onto their headset. This particular design decision allows a much slimmer headset and a very Apple thing to do.

Quest 3 headset has similar provisions for clip-on lenses, but my Quest 2 did not. And even though Quest 2 technically allowed for eyeglasses, it is a tiny bit too narrow for my head and would pinch my glasses’ metal arms against my head. I thought having corrective lenses inside the headset would eliminate that side pressure and was worth investigating.

Since Zenni isn’t standing by to make clip-on lenses for my Quest 2, I thought I would try to get creative and reuse one of my retired eyeglasses. I have several that were retired due to damaged arms and they would be perfect for this experiment. I selected a set, pulled out my small screwdriver set, and unfastened the arms leaving just the front frame.

For this first test, my aim is for quick-and-dirty. I used tape to hold the sides in place. For this first test I didn’t bother trying to find an ideal location.

The center was held with two rolled-up wads of double-sided foam tape. I believe the ideal spacing is something greater than zero, but this was easy for a quick test.

Clipping the face interface back on held my side strips of tape in place. I put this on my face and… it’s marginally usable! My eyesight is bad enough that I would just see a blur without my eyeglasses. With this taped-on solution, made without any consideration for properly aligned position, I could make out majority of features. I still couldn’t read small text, but I could definitely see well enough to navigate virtual environments. I declare this first proof-of-concept test a success, I will need to follow it up with a more precise positioning system to see if I can indeed make my own corrective lenses accessory for my Quest 2.

Roger Cheng

Reducing VR Headset Isolation

One advantage of Quest 2’s standalone operation capability is easy portability. I have a friend who was curious about VR but wanted to get some first-hand experience, and we were able to meet up for a demo with my Quest 2. No need to lug around a powerful PC plus two lighthouse beacons for a Valve Index.

At one point during the test drive, my friend turned towards me to talk about something. He can see where I sat as he had pass-through camera view active, but all I saw in return was the blank white plastic front surface of my Quest 2. It was a little disconcerting, like conversing through an one-way mirror. After that experience I understood the problem Apple wanted to solve with Vision Pro’s EyeSight feature.

It’s a really cool idea! EyeSight is a screen mounted on front of the headset and displays a rendering of the wearer’s eyes so people around them has something to focus on. There’s a lot of technical sophistication behind that eye rendering: because Vision Pro tracks direction of wearer’s gaze, those replicated eyes reflect the actual direction wearer is looking at. Our brains are high evolved to interpret gaze direction (very useful skill out in the wilderness to know if a saber-toothed cat is looking at us) and EyeSight aimed to make it effortlessly natural for all our normal instincts and social conventions to stay intact.

I have not seen this myself but online reports indicate EyeSight falls short of its intention. The screen is too dark to be visible in many environments, a problem made worse by the glossy clear outer layer reflecting ambient light. It was further dimmed by a lenticular lens layer that tries to give it a 3D effect, which is reportedly not very convincing as those rendered eyes are still obviously in the wrong place and not the real eyes.

Given Apple’s history of hardware iteration, I expect future iterations of EyeSight to become more convincing and natural for people to interact with. In the meantime, I can build something with 80% of the functionality for 1% of the cost.

I stuck a pair of self-adhesive googly eyes(*) to the front of my headset, and that will give human eyes something to look at instead of a blank white plastic face. It bears no resemblance to the wearer’s eyes within (or at least I hope not) and does not reflect actual gaze direction. On the upside, it is a lot more visible in bright environments and a far more amusing. Yeah it’s a silly thing but don’t worry, I have serious headset modification project ideas too.

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

Roger Cheng

Quest 2 Standalone and Mixed Reality Operation

While it was instructive to compare Quest 2 specifications with my other VR headsets, the biggest reason I wanted to try a Quest 2 is its standalone capability. After spending some time I’ve decided I’m a fan. It’s much easier to enjoy a virtual environment when I’m not constantly kicking away the cable tethering me to my gaming PC. All else being equal, a wireless experience is superior. Unfortunately, all else are not equal. The cell phone level hardware in a Quest 2 renders a decidedly lower fidelity world relative to what a modern gaming PC can render. It’s a nonissue for something simple and abstract like Beat Saber, but anything even slightly ambitious looks like a PC game from at least ten years ago.

One way to have the best of both worlds is wireless streaming from a gaming PC to my Quest over home WiFi. I tried Steam Link on Quest and was impressed by how well it worked. Unfortunately, it doesn’t work quite well enough just yet. When I’m playing games on a monitor, a few milliseconds of latency plus an occasional (about once per minute) stutter of one or two frames is fine. But on a VR headset, it quickly gives me motion sickness and a headache. Supposedly this can be improved with a WiFi 6 router, but I’m not willing to replace my home WiFi infrastructure for this feature. For the immediate future, I’m happy using my Valve Index for SteamVR experiences.

Mixed Reality

And finally, Meta’s push for Mixed Reality is still a question mark. All three of my VR headsets let me use their cameras to see real-world surroundings. But Quest is the only one of the three to do the work to map that camera footage into a convincingly realistic spatial layout around me. The HP WMR and Valve Index camera views can give me a rough idea if I’m about to run into a wall, but neither are properly mapped enough for me to, say, reach out and grab something.

To support mixed reality scenarios, Quest advertises hand-tracking capabilities for controller-free experiences. Supposedly this works well on the Quest 3, which has additional color cameras for the purpose. My house has beige walls and carpet so my hand has poor contrast for Quest 2’s black-and-white cameras to pick out. It’s pretty unreliable today.

Both of these capabilities show promise, but they’re both relatively new and I will have to wait for novel usage to emerge in mixed reality experiences yet to come. Apple’s Vision Pro is all-in on mixed reality, though, and offers to solve a problem that the Quest 2 does not.

Roger Cheng

And A Quest 2 Too

One reason I was willing to take apart my old HP Windows Mixed Reality system is the Meta Quest 2. Now with the Quest 3 taking mainstream position in their product line, Quest 2 inventory is getting cleared out at $200. That price was too tempting to resist so I got one even though I had a perfectly functional Valve Index. Here are some notes from my first hand experience.

Versus HP Windows Mixed Reality

I did not find a single spec sheet advantage my old WMR headset had over the much younger Quest 2. Technology moves fast! Quest 2 has higher screen resolution, integrated microphone and headset, and controllers that were happy to run on a single nominal AA battery instead of demanding two fully-charged AAs. Both used camera-based inside-out tracking but Quest 2 maintained better tracking because it used four cameras instead of two, and those cameras did not demand I turn on every light in the house if I wanted to use it at night. Quest 2 had some level of IPD adjustment with three settings, whereas the HP had no IPD adjustment at all.

I have not yet decided if I prefer Quest 2’s elastic headband versus HP WMR’s headband. I think the HP headband was the best part of the device and I may try 3D printing an adapter to use it with my Quest 2 to see if that’s an improvement.

Versus Valve Index

On the spec sheet Valve Index has a resolution advantage to the Quest 2. Fewer display pixels spread out across a wider field of view. In practice, I found the wider field of view much more important for immersive VR. I am happy making the tradeoff for better field of view but obviously I wouldn’t say no to both if I can get it in a future headset.

Beacon-based tracking used by Index meant I had to add those two little boxes in my room, but the results are worth it. Index has consistently better tracking especially for games where my hands have to move out of my field of view. (Reach behind my back or have a hand on my chest while looking up.) The Index controllers themselves are also much better than Quest controllers, with individual finger sensing, grip pressure sensing, and straps allowing me to open my grip without the controllers falling out. It’s a great immersion advantage, too bad Half Life: Alyx is the only game that takes full advantage of Index controllers.

Both have integrated microphone and speakers, but the Valve Index delivered much better positional audio. Weight of an Index is significantly heavier but part of that weight is the headband balancing things across my head versus Quest 2’s thin elastic band. And finally, Index has better optical adjustment capabilities. Not only smooth IPD adjustment (instead of three fixed positions) but also fore-aft adjustment.

Index is a much more comfortable headset for longer sessions and provides a more immersive VR experience compared to a Quest 2. But we have to consider their relative price tags. It’s better, but it’s not five times better. Even more if you count cost of a gaming PC! Plus, the comparisons here overlook what’s arguably Quest 2’s greatest advantage: it doesn’t need an associated gaming PC at all.

Roger Cheng

HP Windows Mixed Reality Controller

One advantage of tearing down a VR system is that many things come in left-right pairs. After taking apart the first one, I learn lessons that help tearing down the second one more successful. It was true of headset LCD screens, and it is also true for the controller.

The parts are not interchangeable between these two, including the battery compartment covers that are almost but not identical.

Once the cover was removed we see four obvious fasteners to start.

There’s a fifth fastener, hidden under a faceplate held with clips. I didn’t find this the first time and ruined some things, but I was able to take this picture on the second pass.

Once those five screws are removed, the back cover is held only by clips and can be popped off.

The index finger trigger was a surprise: instead of a potentiometer, there is a small magnet. I think component U4 on the joystick circuit board is the Hall effect sensor reading magnet position for an analog value representing position of finger trigger.

There’s nothing on the other side that look like a Hall sensor. Just a big joystick, an additional button, and a few resistors+capacitors.

Once the joystick circuit board was removed, the second screw holding the LED ring in place became accessible and the LED ring can be freed. I’ll come back to this later.

Below the LED ring is an Y-shaped bracket holding the capacitive touch pad in place.

Once removed, releasing a trio of clips freed the touch pad.

Leaving the main controller logic board as the final component still in the handle, held by two more screws.

The vibration motor is the largest component on the back.

Almost everything is on the front, including the most surprising component J7: a 10-pin FPC connector is populated on this circuit board, but there was no associated FPC in the final product. Why is it here?

Now I return to the LED ring. No fasteners were visible so I started prying at seams.

Some clips popped loose and half of the mounting bracket came free.

Releasing more clips freed the inner ring.

All position reference LEDs were on a single long FPC, wound around the ring and folded into position. Small screws are distributed all around the perimeter to ensure everything is fastened tight and LEDs held in position.

But that’s a solvable problem.

Once the innermost ring was freed, the LED host FPC could be peeled off.

LED array laid out flat on the workbench.

Every time I take apart a gaming peripheral, I am amused by the thought this single controller by itself has more computing power than an entire Atari 2600 console.

Roger Cheng

HP Windows Mixed Reality Headset (VR1000-100) Display

I’m taking apart my soon-to-be-bricked HP WMR headset. Mainly following the community contributed teardown guide on iFixit plus my own detour into stuff like the headband. My next detour is to take apart its display unit.

The iFixit community guide left it as a single unit, with good reason. I found out it is a slim lightweight assembly mostly held together with adhesive strips. (Double-sided tape) I’m not sure it is possible to disassemble it neatly. My disassembly was an irreversibly destructive procedure.

The display unit consists of two nearly identical assemblies, one for each eye. Given that fact I am grumpy they didn’t design a way to adjust the distance between them to match an user’s interpupillary distance. I had thought that limitation reflected a headset built on a single wide LCD a la Google Cardboard. But it wasn’t! They were two separate square LCD units. Majority of wires lead to the actual liquid crystal matrix. The four-pin connector to the right lead to an LED strip for backlight.

I tried to disassemble the right eye assembly first, starting from the back. After releasing a metal frame fastened with six screws, I found everything else was taped down. Peeling this backlight diffuser assembly broke the white plastic frame because that thin strip of tape was apparently stronger than the plastic.

After much snap-crackle-and-popping, the light diffusion films were removed and I could see the row of white backlight LEDs.

I managed to peel off the LED strip intact…

But I completely destroyed the LCD matrix in doing so. That’s a thin sliver of LCD stuck to the back, with its matrix circuitry visible. Ugh, what a mess.

For the other side, I decided to try approaching from the front. I first removed the Fresnel lens, which was held by its own ring of adhesive tape.

Carefully pushing from the front allowed me to remove this second screen assembly intact. That’s better than before!

But I still couldn’t cleanly separate the LCD matrix from its backlight. Glass cracked, liquid smeared, plastic tore. It ended up just as big of a mess as the first try. Oh well.

I doubt I could line up the diffusion film with the LED strip again, so I failed to salvage two diffuse square white light sources. But the LED strips themselves might still be useful. They’re good candidates for building a rig to side-illuminate small circuit boards. These Fresnel lenses will join my salvaged Google Cardboard lenses in my bin of parts awaiting potential future projects.

Next up: the controllers.

Roger Cheng

HP Windows Mixed Reality Headset (VR1000-100) Teardown

I decided to tear apart my Windows Mixed Reality VR headset because it will soon become just a paperweight. I don’t expect to find much that I can repurpose, but I still wanted to see what’s inside. Thankfully someone has already written a teardown guide on iFixit which will save me time. It also lets this post focus on items not already in the guide.

The guide has location for all the screws, but one thing not explicitly called out is the fact the screws are tiny and some of them are very deeply recessed. A large handle with an interchangeable screwdriver bit wouldn’t fit here. I had to dig up an actual tiny screwdriver.

A good VR headset would minimize weight hanging on our head. So I had expected to find a fully optimized design but I see many unpopulated footprints on the main logic board. I don’t know enough to speculate what they might have been but it’s clear this board isn’t as optimized as I had thought it would be. Sure, we’re probably talking about surface mount components that wouldn’t weigh much on their own, but consider their downstream effects. Their footprints and associated wiring makes this logic board larger. Which meant the enclosure had to be larger, and so on. Each individual step may be a small weight gain but they add up.

The guide got as far as removing this headband assembly and didn’t go into any more detail about it. This headband was very adjustable to accommodate a wide range of human head sizes and well padded for comfort holding up the weight that it did. I thought this headband might be the component most likely to get reused. Technology and market forces has rendered rest of the headset obsolete, but I still have the same head!

The hinge mechanism was secured by four screws hidden under a sticker.

Opposite those screws were a set of four clips.

Removing screws and releasing clips allowed the hinge mechanism to slide free of the visor chassis.

The hinge came apart easily once freed. It looks very promising for reuse if I ever wanted to build something to wear on my head. The underlying spring-loaded mechanism has a round output shaft with flattened top and bottom, a shape I should be able to 3D print and mesh with. Or I could try to design and print something that fits into the clips and screws. Both are possibilities for the future. Right now I’ll set it aside to look at the display unit.

Roger Cheng

End of Windows Mixed Reality

In December 2023 Microsoft announced that Windows Mixed Reality has been deprecated and will be removed from Windows 11 24H2. This did not come as a surprise, as the platform hasn’t seen any investment in years. But it does mean my HP WMR headset will officially become a paperweight later this year.

This is fine by me, because my headset has pretty much been a paperweight since I damaged its cord. I tried fixing it and was seemingly successful, but there was a chance my fix is flawed. An errant pin could potentially ruin an expensive video card so I never really put the headset back into use. It is old anyway, lacking features of newer headsets. Heck, it was old and out of date when I got it! At that time, WMR was already… not a resounding success… and my local Best Buy decided to clear out their slow-moving inventory with heavy discounts.

What could I do with it now? There was never any compelling WMR exclusive experience for me, so I don’t have anything to revisit before it’s gone. And since I’ve upgrade to a Valve Index headset, that gives me a superior experience for everything in SteamVR. I guess I could use the deprecated WMR headset for experiments that I don’t want to risk on my expensive Valve Index, but I don’t have any project ideas along that direction. There’s no particular reason to hang on to it “just in case” an idea comes up because (1) it’ll stop working by the end of the year, and (2) if I want VR experiments with an affordable headset, I have to option to go pick up a Meta Quest 2. Which is not only affordable, but would let me explore untethered VR as well as opening the door to Quest exclusive experiences.

During my long inkjet teardown/Dell XPS debugging saga, I would frequently think about what I could do with this obsolete WMR headset. After a few months of not coming up with anything interesting, I will proceed with the ultimate fallback option: it is teardown time!

Roger Cheng

My Cell Phones Before Android, 1998-2013

I recently rediscovered this picture of all my cell phones from 1998 to 2013. I took this group picture shortly before sending most of them to electronic waste disposal. At the beginning of that fifteen year period, these were “cell phones” to specify they worked on a wireless network. By the end of that period, they are just “phones” and what used to be “phones” had become “landline”. It would have been symbolic to post this note on August 30th 2023 as that would have been the picture’s 10th anniversary, but I’m a few months late.

The oldest phone on the far left is a Sony CM-H888. I bought it in September 1998 and at the time it was a wonder of miniaturization much smaller than its contemporary analog peers. Yes, analog! This was a telephone for making voice calls over analog cellular network and nothing else. No internet, no apps, not even SMS. It looks bulky compared to the rest of this lineup mostly because of its 4*AA NiMH battery pack consuming over half of its volume. It is the only device on this list not powered by a lithium-ion battery.

Rapid technology advancement motivated me to part with my money. I upgraded to a Nokia 8260 a year later (October 1999) which weighs less than half as much (220g vs. 97g), eliminated the protruding antenna, and is a comfortable fit in my pocket instead of a barely-fit bulge. Multiple different technologies helped make this possible, including lithium-ion battery and a switch from AirTouch Cellular‘s analog network to AT&T Wireless TDMA digital cellular. It also gave me first exposure to a phone app in the form of Nokia’s legendary snake game.

A few years after getting the Nokia 8260, I bought a Compaq iPaq personal digital assistant (PDA) to help track my calendar and related adulting information that I could no longer all keep in my head. I appreciated that I had a pocket reminder of my responsibilities, and I admit to a certain level of Geek Cred for carrying around these electronic devices, but it still meant I was carrying them!

Consolidation came in December 2003, when I upgraded to a Motorola MPx200. It was the device that launched “Windows Mobile Smartphone” OS which gave me phone apps to functionally replace my PDA. The screen resolution of 176×220 was a huge upgrade over the Nokia brick but lower than iPaq’s 240×320. Plus, both of those screens were monochrome and now I have a color screen. Upgrading from TDMA to GSM digital cellular also meant I gained access to SMS text messaging. And finally, switching to a flip phone eliminated accidental butt-dials.

But it was a lot thicker than the Nokia, and didn’t fit in my pocket as nicely. So a year later (December 2004) I upgraded to an Audiovox 5600 (HTC Typhoon). It has all the features of the Motorola MPx200 at size of the Nokia 8260, so it’s almost the best of both worlds. The only thing I consider a downgrade is the fact butt-dials started happening again. Especially annoying was a feature where holding down “9” would automatically dial “911” and I could not figure out how to disable it.

So when the Cingular 3125 (HTC Startrek) launched, it caught my attention and I bought one in March 2007. It’s a flip phone to eliminate embarrassing butt-dials again, but far thinner than the Motorola MPx200. Hardware had advanced enough to put iPaq resolution screen (240×320 and in color) into a phone, and the laser-etched metal keypad looks way better in person than in pictures.

The first Apple iPhone also launched in 2007, but as an expensive premium product. My CIngular 3125 cost a small fraction of the iPhone up front, and did not require an expensive cellular data plan as the iPhone did. But the cost gap narrowed over the following years. Apple iPhone prices (along with corresponding data plan prices) eventually dropped to within reach of mass market consumers, and it was clear slabs of touch screen glass were the way of the future.

The AT&T HTC Pure (HTC Touch Diamond2) weighted about as much as my Cingular 3125. It lost the cool laser-etched keypad in exchange for a much larger and higher resolution (480×800) screen. It was one of several non-Apple efforts to follow iPhone’s lead as of January 2010 and a pretty poor showing at that. The marketing team tried their best trying to find advantages but it was pretty futile. Example: The 480×800 screen resolution was higher than the iPhone 3, but that marketing item was quickly buried by “retina display” of iPhone 4. Phones like HTC Pure could only compete at a lower price and I was fine with that. My Cingular 3125 was falling apart, held together with glue and tape. A cheap not-as-good-as-iPhone unit would suffice.

Minimizing usage of expensive data plan meant my HTC Pure did not get used as a smartphone very much. Mostly just voice calls and calendar, similar to how I had used my earlier phones. I didn’t know what I was missing out on until I upgraded to a Samsung Focus in November 2010. Windows Phone 7 was a huge advancement. Its first-party experience became a credible competitor to iPhone and Android, but third-party app support was inferior and would never catch up.

My biggest complaint with the Samsung Focus was its AMOLED screen. The bright high-contrast colors worked well for video and pictures, but its RGBG PenTile matrix proved horrible for text legibility at those resolutions. So when the Nokia Lumia 900 launched with classic RGB color pixels, I jumped over in July 2012. I was happy to accept some color and brightness limitations of a LCD screen in exchange for more legible text. Beyond its screen, I preferred Nokia’s sleek industrial design over Samsung’s anonymous black blob.

And finally, at the far right of this lineup, is a Nokia Lumia 620 I bought in May 2013. All the Nokia design and RGB matrix of the 900, but in a smaller package running Windows Phone 8. It was fine, but it was still a Windows Phone. After multiple major updates (7.5, 7.8 and 8) it became clear Microsoft was unable or unwilling to match iOS/Android on third-party app support. After losing faith in Microsoft, I never upgraded to Windows Phone 10… er, sorry, “Windows 10 Mobile”. Because rebranding always solves fundamental product issues.

I switched to Android in 2015 with a Nexus 5 and I’ve had Android phones ever since. I still have many of them (and try to keep them running) but a group photo wouldn’t be very interesting as they’re all touch screen slabs. (Effectively this photo.) RGBG PenTile AMOLED panels came back into my life again with recent phones, but I found that I didn’t mind it as much at modern phone screen resolutions. I have less than a dozen apps installed on my current phone so I never got into apps in a big way. But if I needed one, I can be confident an Android app exists. I no longer have to worry about whether an app exists for Windows Phone.

I hardly noticed when Microsoft finally pulled the plug on their phone OS efforts. I was long gone. It’s hardly the only platform I own that Microsoft axed.

Roger Cheng

Canon 210 (Black) And 211 (Color) Cartridges

While reviewing my notes about getting my Dell XPS 8950 fixed, I realized an item from my inkjet teardown slipped through the cracks: an aborted teardown of its 210XL and 211 ink cartridges. I wasn’t terribly interested in their internals. So when I encountered its robust construction I just shrugged and moved on. Still, there were a few interesting observations.

When I looked at the print carriage internals, I was not surprised to see the black cartridge had fewer electrical contact points than the color cartridge. However, I was surprised to see it’s not one-third the amount. It has to deal with just black instead of cyan, magenta, and yellow. Why does it have well over 1/3 the contact points?

I saw the answer when I flipped those two cartridges over and compared them side by side. The single-color black ink print head is double the height of the three-color ink print head. When printing purely in monochrome, it can print a band twice as high in a single pass so the paper can advance twice the distance basically doubling print speed. Assuming all else are equal, it would imply the black ink cartridge would need 2/3 the contact points of the color cartridge rather than 1/3. The actual numbers are 20 contacts for black and 36 contacts for color. Close enough for me to declare mystery solved.

Those contact points are on a thin flexible printed circuit and held down by four melted plastic rivets. I could cut them flush with a knife to free the thin sheet.

Once freed, I took a picture of the exterior side…

… and the interior side. The print head is to the left of these two pictures so it’s no surprise a bunch of copper traces lead that direction, but I was intrigued by the traces running off the edge to the right. What purpose did that serve?

I didn’t see any more rivets I could cut, and I couldn’t see anything else I could release. Trying to see what might be holding things in place, I gave the thin sheet a firm tug and it ripped off. The answer is, apparently, glue. Underneath the ripped-off sheet is the print head embedded inside cartridge enclosure. I saw no fasteners or clips. I think it is either glued in or molded in.

I tried prying against a corner and ended up braking off a piece. The whole thing is made of a very strong material. When it is over stressed, its brittle nature causes it to shatter instead of bend.

Looks like the enclosure is bonded strongly enough to the actual print head that they broke apart together. There’s no way to get further inside without being extremely destructive about it, which won’t teach me anything interesting, so I stopped here.

Roger Cheng

Dell XPS 8950 Components Replaced Under Warranty

My six-month-old Dell XPS 8950 has been exhibiting intermittent bug checks. (Blue screens of death.) Since it was still under warranty, I wanted Dell to fix it. The tech support department tried their best to fix it in software, but they eventually decided hardware component replacement will be required to get this system back up and running reliably.

The premium I paid for XPS included on-site service visits as a perk. Dell dispatched a technician (an employee of WorldWide Tech Services) to my home with a job order to replace SSD and power supply. This made sense: a bad SSD would corrupt system files and cause the kind of seemingly random and unpredictable errors I see. If the power supply had gone bad, intermittent power glitches can do the same. As far as system components go, they are relatively inexpensive and easy to replace, so it made sense for Dell to try that first.

Unfortunately, this repair job went awry. When the technician powered my system back up, there was no video from the RTX 3080 GPU. Intel’s integrated video worked if the GPU was removed so the rest of the system seemed fine. A follow-up visit had to be scheduled for another technician to arrive with a replacement RTX 3080 GPU to get things back up and running. I hope the first technician didn’t get in too much trouble for this problem as RTX 3080 cards are not cheap.

The evening after the system was back up, another bug check occurred. Two more occurred within the 24 hours that followed. I reported this back to Dell and they asked if I would be willing to send the system to a repair depot. I didn’t care how it was done, I just wanted my system fixed, so I agreed. They sent me a shipping box with packing material and a shipping label. I guess they didn’t expect people to hang on to the original box! (I did.)

Looking up the shipping label address, I found a match for CSAT Solutions. Apparently contracted by Dell to perform such repairs. These people worked fast! According to FedEx tracking information, it was delivered to CSAT at 11AM and by 4PM the box was back in FedEx possession for the return trip. I had set up the machine to run Folding@Home and I included instructions to reproduce the problem, but it’s clear they ain’t got time for that nonsense.

An invoice in the box indicated they replaced CPU and RAM. Two more components that, if faulty, can cause random bug checks. They are significantly more expensive than a SSD or power supply so I understand why they weren’t first to be replaced. (A RTX 3080 cost more, but wasn’t part of the plan.)

I reinstall Windows 11 again and fired up Folding@Home. This time there were no bug checks running for seven days nonstop. Hooray! I’m curious whether it was CPU or RAM at fault (or both?) but at this point I have no way to know.

Due to component replacements, I almost have a different computer. Of its original parts, the metal enclosure and main logic board are all that remained. Dell has fixed the computer under warranty with no financial cost to me but significant time cost. If I value my time at, say, $50 an hour, I would have been better off just buying a new computer. As for Dell, whatever profit they had made on this sale has been completely erased and became a net loss. I’m glad this problem was fixed under warranty, but both sides prefer to avoid doing it at all. I hope this gives them a financial incentive to improve system reliability!

Despite the headaches of this particular episode, the fact it was repaired under warranty made me quite willing to buy more refurbished Dell computers.

Roger Cheng

Notes On Diagnostics From Dell Support

My Dell XPS 8950 has started exhibited unpredictable bug checks. (Blue Screen of Death) I poked around Dell’s SupportAssist software and found a lot of promising troubleshooting tools, but none of them fixed it. Out of ideas on software fixes, and unwilling to void the warranty by modifying hardware, I used SupportAssist text chat feature to open an official trouble ticket with Dell technical support. They eventually fixed the issue, but it took a few weeks to get there.

As expected, they wanted to try the easy things first. This meant repeating many SupportAssist tools which I already knew would be doomed to fail. And Windows tools (like restore points) that did no better. Since hardware diagnostics tests passed, their suspicion moved to operating system corruption. This involved trying a lot of procedures I already knew about, and have already run, but they want to do it again. There were a few bits of novelty:

Throughout this arduous process,I was instructed to reinstall Windows three separate times in three different ways: first with SupportAssist’s OS reinstall option, then Windows’ built in recovery option, finally a clean install via an USB drive created with Microsoft’s Media Creation Tool. This is on top of the re-installation I had already performed before contacting Dell support. With all this practice, I got really good at Windows setup!

Each time I reinstalled Windows, I had to reinstall SupportAssist. Clicking on text chat created a new chat session. Which meant I was sent to someone expecting to open a new ticket and I’d have to spend time to get them straightened out with my existing ticket number.

With each bug check, I get a crash memory dump to prove their latest idea hadn’t resolved my issue. Sadly Dell’s support ticket web interface allowed only a maximum of five attachments. I quickly reached my limit and additional memory dumps had to submitted by sharing files via my Microsoft OneDrive and Google Drive accounts and sending a link via text chat. This was… sub-optimal.

Weeks later, I’ve exhausted all their scripted solutions and finally granted an escalation to senior support technicians. They reviewed my ticket and came to the conclusion I hoped they would: some hardware components would need to be replaced.

Roger Cheng

Notes on Dell SupportAssist

I have a thorny issue with my XPS 8950. The symptom is an intermittent bug check (a.k.a. blue screen of death) that is not readily reproducible and, even when it occurs, the error code varies wildly in type and in location. My previous trouble-free Dell computers have allowed me to ignore Dell’s tech support portal. Now I have a troubled PC and have to learn what’s in Dell’s SupportAssist software.

Dell SupportAssist is primarily a native Windows application that is pre-installed on every Dell PC. If it is lost, SupportAssist can be downloaded from Dell’s website. (I had to do this several times after performing operating system reinstall as a diagnostic procedure.) It has several roles to play in regular maintenance:

  • Look for common configuration problems and tries to fix them.
  • Download drivers and other system files, though mostly supplanted by Windows Update. I even got BIOS update 1.16.0 from Windows Update before it showed up as an option in SupportAssist.
  • Clean up unused files to free up disk space.

SupportAssist also included troubleshooting tools including:

  • Examine Windows system events. SupportAssist recognized that I had been experiencing bug checks, and even offered a “Fix Now” option. It’s not obvious what that did, but it didn’t help.
  • Perform a suite of hardware tests. CPU tests, memory tests, disk tests. I was amused it even spun up each of the fans.

Regarding the hardware tests: there’s also a separate piece of software that can run independent of Windows. Its title bar calls itself “SupportAssust | On-board Diagnostics” and it lives on a separate disk partition. To launch it, we have to trigger the BIOS boot select menu and select “Diagnostics”. My computer passed all of these tests as well, including running everything under “Advanced Test” with “Thorough mode” selected.

This diagnostics partition was deleted when following directions from Dell tech support to perform a completely clean install. I was worried about that — it seemed useful! — but I later learned SupportAssist Windows application can re-partition the hard drive and reinstall that Diagnostics partition.

There is one worrisome aspect of SupportAssist. When this native Windows application is installed on a system, the Dell web site running in a browser seems to be able to query hardware configuration in order to offer the appropriate documentation and driver downloads. How are those components communicating? I’m worried about that channel being a potential venue for security exploits.

There are many other features of SupportAssist I didn’t investigate because they didn’t seem helpful to me. Like tools to migrate data from one PC to another, and naturally an upsell for extended warranty coverage.

I ran every SupportAssist maintenance task and diagnostic test I could find, none helped. As a last resort I activated its operating system reinstall procedure, and that didn’t help either. I’m out of ideas for software fixes. If this were one of my home-built desktop PCs, I would start swapping out hardware to see if I can isolate it to a particular component. However, this computer is still under warranty so I don’t want to do anything that would void said warranty. If hardware replacements are to be done, it will have to be done by Dell people on Dell dime under warranty. To get that process started, I have to contact Dell technical support. I could call them over the phone, but that doesn’t seem like the best approach for an intermittent error that takes a day to reproduce. Fortunately SupportAssist includes a text chat client, and that seems more practical for my situation.

Roger Cheng

Dell XPS 8950 Bug Check Codes List

My Dell XPS 8950 I bought primarily for SteamVR started exhibiting bug checks at around six months old. It was eventually fixed under Dell’s one-year warranty, but the journey started with an attempt to diagnose it myself. Stressing it with Folding@Home would crash it once roughly every 12-24 hours.

When Windows halts with a bug check, a memory dump file is written to disk for debug purposes. It takes significant expertise to dig through a memory dump file to pinpoint a root cause. However, it’s pretty easy to get a general idea of what we are dealing with. We can install Windows debugger (WinDbg) and use its built-in automated analyzer to extract a top-level error code we can then look up online. Over the course of two weeks I ran Folding@Home to build a collection of memory dump files, hoping to find commonalities that might point at a source.

The best case scenario is to have the same bug check code on every dump, occurring in the same operating system component. What I got instead is a list of thirteen codes (appended at the bottom of this post), some more often than others. And even worse, they didn’t all happen at the same place in the system but was spread all around. The only vague commonality between them is an invalid memory operation. Sadly, “invalid memory operation” is too broad of a category to tie to a root cause. I became quite discouraged looking over those memory dumps.

I know Dell tech support has a database of bug check codes and a list of diagnostic steps to address each of them. First level support technicians are trained to tell the customer to try each item in turn. Figure a half dozen things they want me to try (probably starting with “please turn off and back on again”…) for each of 13 possible codes means I will have to trudge through a lot of those procedures.

Eventually my support ticket will establish a widespread pattern that escalate my case to more senior support staff who will look at the problem more holistically, but I have to earn it with persistence! I will be spending a lot of time with Dell tech support, starting with their preinstalled troubleshooting tool called SupportAssist.

Bug check codes encountered, with URL of the Microsoft reference page and the first sentence of their explanation pasted in after the code.

Roger Cheng

Dell XPS 8950 Stress Test with Folding@Home

I had another lengthy saga running In parallel with my lengthy Canon Pixma MX340 teardown. The Dell XPS 8950 I bought primarily for SteamVR with my Valve Index began exhibiting bug checks on an irregular basis. This is not good. I paid a premium over similar-spec computers on the expectation that a XPS would be more reliable and, failing that, Dell is more likely to fix things that go wrong. Well, the first part turned out to be wrong. Thankfully the second part was eventually tested to be true, but it took some work to get there.

The first thing I needed was a better way to reproduce the issue. I want to collect many bug check memory dumps to compare them against each other, and I needed a way to verify the problem has been resolved or not. Since I bought this computer mainly for SteamVR, the bug check usually happens while I’m in the middle of a VR session. It spoiled a few Beat Saber songs and abruptly ended firefights with Combine soldiers in Half Life: Alyx, but not every VR session triggered the problem and I wasn’t going to just stay in VR until it occurred.

I found hardware tests in Dell’s SupportAssist tool (more on SupportAssist in a future post) and ran those. My computer passed the tests with no errors. I looked for a way to run these tests in a loop but didn’t find a way to do so.

I tried just leaving the computer on and running, but not doing anything in particular. After a week, I got two bug checks. This is better than unpredictable crashes in VR sessions, but waiting 3-4 days between reproducing a failure is still not great.

I increased system workload by installing and running Folding@Home. It kept the GPU busy but CPU utilization would drop off after a few minutes. I eventually figured out Windows 11 detected a long-running compute process and decided to restrict Folding@Home to the four power-efficient E-Cores on my i7-12700 CPU. Gah, foiled! I worked around this by disabling the E-Cores in system BIOS. (Where they were called Atom Cores.) With E-Cores out of the picture, CPU utilization stays at 100% with all eight hyper-threaded P-cores running at full blast.

I would rather have a procedure to consistently and immediately reproduce the crash but I never found one. Running Folding@Home the bug check would usually occur within 12-24 hours and this was the best I’ve got. Over the course of about two weeks, Folding@Home helped me generate a decently sized collection of bug check crash memory dumps to examine.

Roger Cheng

Canon Pixma MX340 Teardown Index

I’ve taken apart my retired Canon Pixma MX340 multi-function inkjet. Its task-specific plastic components are heading to landfill and its electronics core twist-tied to a sheet of cardboard for potential future reuse. I found a lot of interesting details as I went though this teardown and learned lessons that I hope to apply to future projects. I wrote down a lot of my observations here, so much that it has become pretty unwieldy to find specific information. Text search helps, but I also found myself frequently clicking “Next Post” and “Previous Post” to find a specific piece of information.

This post will be my first effort to help streamline finding references: all my MX340 posts listed in chronological order with as few words as practical (sometimes just a title excerpt) to remind my future self of their relative context. There are probably other ways to organize this information, but I am ignorant of the library science involved so this first effort is merely chronological.

Introduction

Tearing down inkjet printers as a learning exercise. General thoughts followed by an overview for this Canon MX340.

Phase 1: Functionality-Preserving Disassembly

Phase 2: Probe certain electronic subsystems as system runs

Phase 3: Disassembly Without Concern for Preserving Functionality

And finally, the summary index. (You are here!)

Bonus item: aborted teardown of Canon 210 (black) and 211 (color) ink cartridges.

Follow-Up Project: CircuitPython and MX340 Control Panel

CircuitPython learning project: write code to allow a microcontroller to communicate with control panel following precedence of MX340 main logic board.

At this point the exploratory project was getting mature enough for conversion to library.

Finale: Tiny Cat & Galactic Squid on MX340 LCD.

Whew, that was a lot to write down, but at least it wraps up documenting this lengthy project. Now I can document another lengthy saga that took place at the same time: debugging bug checks on my Dell XPS 8950.

Roger Cheng

MX340 Teardown Complete With Loose Ends Tied Up

I’m done taking apart my old retired Canon Pixma multi-function inkjet, with salvaging its scanner flatbed glass as my final act. While this marks the end of my teardown, this is not the end of my MX340 adventure: there are many components that have future project potential. I have several ideas that may or may not put certain parts to other use. But the end of my teardown is a good place to take a break, let those ideas stew for a while.

Since I want a change of pace, I need to clear MX340 components off my workbench. And since I want to reuse them in the future (or at least preserve the option) I can’t just sweep them into a box. There are some fairly fragile parts here, with my top concern being the X-axis optical encoder strip and its Y-axis counterpart encoder disc. Also, the contact image sensor bar would be more useful if it does not get scratched up.

I decided the minimum effort way to store these components is to revisit an idea I had earlier with prototype circuits: mount components on a sheet of cardboard. My priority here is to ensure parts don’t damage each other and that wires are not jerked around. I cut apart a cardboard shipping box and started punching holes for me to secure components with twist ties.

I can even power up the system in this state and watch it go through its power-on self test, probing any circuitry if needed. If I want to run the test, though, I need to make sure the print carriage is dangling over the edge of my table. Given how it extends slightly below cardboard level.

I wouldn’t call this safely packaged — I wouldn’t ship it in this condition, for one thing — but it should be good enough for me to keep everything together without causing damage. Having all of these literal loose ends tied up on a sheet of cardboard means I have the option to stand it vertical leaning against a wall. This only consumes only a few square inches of desktop space, and far less than the full volume of an intact MX340. It’s a good way to clear my workbench so I can think about other things.

That takes care of physical organization, next up is my first stab at information organization.

This teardown ran far longer than I originally thought it would. Click here to rewind back to where this adventure started.

Roger Cheng

MX340 Scanner Glass

My old Canon Pixma MX340 multi-function inkjet is about as taken apart as I want it to be right now. After taking a big group photo of all the components, I started gathering up the plastic that I don’t plan to keep. That’s when I noticed a loose end: two glass panels in the flatbed scanner assembly.

Early in this teardown, I discovered those panes of glass were much thicker than those used in LCD screens and thus far more robust than I had given them credit for. They also had nicely beveled edges so I’m much less likely to cut myself while handling them. Those two traits made it interesting to salvage those panes for my own use, but I forgot about them until now.

These two panes of glass were held with double-sided tape. It was not a surprise to discover the tape had yellowed and hardened, and the adhesive had dried up. It was pretty easy to peel both pieces of glass off their plastic frame.

Some residue was left behind as I peeled, but majority were easy to clean up. Some small streaks will need to be either scraped off with a razor or cleaned off with a solvent.

Underneath the glass is the image sensor homing marker. I thought it was a thin piece of paper, but it was actually a more substantial sheet of plastic and I’m curious why it had to be this thick. It’s almost as thick as the #11 knife blade I used to get started peeling off its adhesive.

I really doubt I’d reuse this homing marking for anything else, but it won’t take much space to hang on to a thin strip of plastic for now. To preserve context I will keep it alongside its matching contact image sensor bar so at least they’re available if I think of something to do with that sensor. Fortunately, I have a convenient piece of cardboard I can use to keep it with the sensor bar.

This teardown ran far longer than I originally thought it would. Click here to rewind back to where this adventure started.

Roger Cheng

MX340 Disassembled And Laid Out

I’ve torn down my retired Canon Pixma MX340 multi-function inkjet almost to its individual components. I was a bit surprised the remaining electronics still ran through its power-on self-test sequence. It failed the test, of course, given how almost all mechanical components have been disassembled. But the fact it ran at all was enough to motivate keeping all the electronics together until I pick off individual pieces for future repurposing.

The same could not be said of its mechanical components. Most of the plastic pieces are very specific to a MX340’s mission of handling paper and that hasn’t been my area of interest. Now that they’ve been taken apart, I no motivation to put them back together again. Another part of this lack of interest is the fact that, thanks to 3D printing, it’s easy for me to create tailored plastic pieces for future projects. I think I will keep the gears because, even though they can be challenging to repurpose, they are difficult to 3D print well. The remaining plastic are landfill bound.

I don’t have any metalworking capability, though, so all these miscellaneous metal bits will be added to my jar of salvaged parts. Joining my existing collection of screws, springs, and shafts.

Before these parts go their separate ways, I laid them all out together one last time. I had originally thought it would be neat to lay them out in a way that maintained their relative position to each other like an exploded-view engineering drawing. But due to how a MX340 is built, it quickly became an impossible task to maintain 3D space relationship of multiple layers on a flat 2D layout.

Ignoring my failure to maintain spacial relationship, this “group picture” showed the large number of parts that go into a multi-function inkjet. I believe an inkjet is the most mechanically complex consumer electronic equipment still on the market. Especially now that VHS decks, audio cassette players, and CD changers have disappeared. Given their complexity it’s amazing inkjets are still sold for well under a hundred bucks. Now that I’ve taken one thoroughly apart I find it more believable they might be sold at low to no profit (or even a loss) for the intent selling profitable ink cartridges.

Taking this apart was a lot of fun! But when putting together this picture, I realized I missed an item on the to-do list: salvage the scanner flatbed glass.

This teardown ran far longer than I originally thought it would. Click here to rewind back to where this adventure started.