PC

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!

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

Configuring Laptop for Proxmox VE

I’m migrating my light-duty server duties from my Dell Latitude E6230 to my Dell Inspiron 7577. When I started playing with KVM hypervisor on the E6230, I installed Ubuntu Desktop instead of server for two reasons: I didn’t know how to deal with the laptop screen, and I didn’t know how to work with KVM via the command line. But the experience allowed me to learn things I will incorporate into my 7577 configuration.

Dealing with the Screen

By default, Proxmox VE would leave a simple text prompt on screen, which is fine because most server hardware don’t even have screens attached. On a laptop, keeping the screen on wastes power and probably cause long-term damage as well. I found an answer on Proxmox forums:

  • Edit /etc/default/grub to add “consoleblank=30” (30 is timeout in seconds) to GRUB_CMDLINE_LINUX if an entry already existed. If not, add a single line GRUB_CMDLINE_LINUX="consoleblank=30"
  • Run update-grub to apply this configuration.
  • Reboot

Another default behavior: when closing the laptop lid, the laptop goes to sleep. I don’t want this behavior when I’m using it as mini-server. I was surprised to learn the technique I found for Ubuntu Desktop would also work for server edition as well: edit /etc/systemd/logind.conf and change HandleLidSwitch to ignore.

Making the two above changes turn off my laptop screen after the set number of seconds of inactivity, and leaves the computer running when the lid is closed.

Dealing with KVM

KVM is a big piece of software with lots of knobs. I was intimidated by the thought of learning all command line options and switches on my own. So, for my earlier experiment, I ran Virtual Machine Manager on Ubuntu Desktop edition to keep my settings straight. I’ve learned bits and pieces of interacting with KVM via its virsh command line tool, but I have yet to get comfortable enough with it to use command line as the default interface.

Fortunately, many others felt similarly and there are other ways to work with a KVM hypervisor. My personal data storage solution TrueNAS has moved from a FreeBSD-based system (now named TrueNAS CORE) to a Linux-based system (a parallel sibling product called TrueNAS SCALE). TrueNAS SCALE included virtual machine capability with KVM hypervisor which looked pretty good. After a quick evaluation session, I decided I preferred working with KVM using Proxmox VE, a whole operating system built on top of Debian/Ubuntu dedicated to the job. Hosting virtual machines with the KVM hypervisor and tools to monitor and manage those virtual machines. Instead of Virtual Machine Manager’s UI running on Ubuntu Desktop, both TrueNAS SCALE and Proxmox VE expose their UI as a browser-based interface accessible over the network.

I liked the idea of doing everything on a single server running TrueNAS SCALE, and may eventually move in that direction. But there is something to be said of keeping two isolated machines. I need my TrueNAS SCALE machine to be absolutely reliable, an appliance I can leave running its job of data storage. It can be argued it’s a good idea to use a different machine for more experimental things like ESPHome and Home Assistant Operating System. Besides, unlike normal people, I have plenty of PC hardware sitting around. Put some of them to work!

Roger Cheng

Dell Inspiron 7577 Laptop as Light Duty Server

I’m setting aside my old Dell Latitude E6230 laptop due to its multiple hardware failures. At the moment I am using it to play with virtualization server software. Virtualization hosts usually run on rack-mounted server hardware in a datacenter somewhere. But an old laptop works well for light-duty exploration at home by curious hobbyists: they sip power for small electric bill impact, they’re compact so we can stash them in a corner somewhere, and they come with a battery for surviving power failures.

I bought my Dell Inspiron 7577 15″ laptop five years ago, because at the time that was the only reasonable way to get my hands on a NVIDIA GPU. The market situation have improved since then, so I now have a better GPU on my gaming desktop. I’ve also learned I haven’t needed mobile gaming power enough to justify carrying a heavy laptop around, so I got a lighter laptop.

RAM turned out to be a big constraint on what I could explore on the E6230. Which had a meager 4GB RAM and I couldn’t justify spending money to buy old outdated DDR2 memory. Now I look forward to having 16GB of elbow room on the 7577.

While none of my virtualization experiments demanded much processing power, more is always better. This move will upgrade from a 3rd-gen Core i5 3320M processor to a 7th-gen Core i5 7300HQ. Getting four hardware cores instead of two hyperthreaded cores should be a good boost, in addition to all the other improvements made over four generations of Intel engineering.

For data storage, I’ve upgraded the 7577 from its factory M.2 NVMe SSD from a 256GB unit to a 1TB unit, and the 7577 chassis has an open 2.5″ SATA slot for even more storage if I need it. The E6230 had only a single 2.5″ SATA slot. Neither of these machines had an optical drive, but if they did, that can be converted to another 2.5″ SATA slot with adapters made for the purpose.

Both of these laptops have a wired gigabit Ethernet port, sadly a fast-disappearing luxury in laptops. It eliminates all the unreliable hassle of wireless networking, but an Ethernet jack is a huge and bulky component in an industry aiming for ever thinner and lighter designs. [UPDATE: The 7577’s Ethernet port would prove to be a source of headaches.]

And finally, the Inspiron 7577 has a hardware-level feature to improve battery longevity: I could configure its BIOS to stop battery charging at 80% full. This should be less stressful on the battery than being kept at 100% full all the time, which is what the E6230 would do and I could not configure it otherwise. I believe this deviation from laptop usage pattern contributed to battery demise and E6230 retirement, so I hope the 80% state of charge limit will keep the 7577 battery alive for longer.

When I started playing with KVM hypervisor on the E6230, I installed Ubuntu Desktop instead of server for two reasons: I didn’t know how to deal with the laptop screen, and I didn’t know how to work with KVM via the command line. Now this 7577 configuration will incorporate what I’ve learned since then.

Roger Cheng

Dell Latitude E6230 Getting Benched

I’ve got one set of dead batteries upgraded and tested and now attention turns to a different set of expired batteries. I bought this refurbished Dell Latitude E6230 several years ago intending to take apart and use as a robot brain. I changed my mind when it turned out to be a pretty nifty little laptop to take on the go, much smaller and lighter than my Dell Inspiron 7577. With lower specs than the 7577, it also had longer battery run time and its performance didn’t throttle as much while on battery. It has helped me field-program many microcontrollers and performed other mobile computing duties admirably.

I retired it from laptop duty when I got an Apple Silicon MacBook Air, but I brought it back out to serve as my introduction to running virtual machines under KVM hypervisor. Retired laptops work well as low-power machines for exploratory server duty. Running things like Home Assistant haven’t required much in the way of raw processing power, it was more important for a machine to run reliably around the clock while stashed unobtrusively in a corner somewhere. Laptops are built to be compact, energy-efficient, and already have a built-in battery backup. Though the battery usage pattern will be different from normal laptop use, which caused problems long term.

Before that happened though, this Latitude E6230 developed a problem starting up when warm. If I select “restart” it’ll reboot just fine, but if I select “shut down” and press the power button immediately to turn it back on, it’ll give me an error light pattern instead of starting up: The power LED is off, the hard drive LED is on, and the battery LED blinks. Given the blinking battery LED I thought it indicated a problem with the battery, but if I pull out the battery to run strictly on AC, I still see the same lights. The workaround is to leave the machine alone for 20-30 minutes to cool down, after which it is happy to start up either with or without battery.

But if the blinking battery LED doesn’t mean a problem with the battery, what did it mean? I looked for the Dell troubleshooting procedure that would explain this particular pattern. I didn’t get very far and, once I found the workaround, I didn’t invest any more time looking. Acting as a mini-server meant it was running most of the time and rarely powered off. And if it does power off for any reason, this mini-server isn’t running anything critical so waiting 20 minutes isn’t a huge deal. I decided to just live with this annoyance for a long time, until the second problem cropped up recently:

Now when the machine is running, the battery LED blinks yellow. This time it does indicate a problem with the battery. The BIOS screen says “Battery needs to be replaced”. The Ubuntu desktop gives me a red battery icon with an exclamation mark. And if I unplug the machine, there’s zero battery runtime: the machine powers off immediately. (Which has to be followed by that 20 minute wait for it to cool down before I can start it up again.)

I knew keeping lithium-ion batteries at 100% full charge is bad for their longevity, so this was somewhat expected. I would have preferred the ability to limit state of charge at 80% or so. Newer Dell laptops like my 7577 have such an option in BIOS but this older E6230 did not. Given its weird warm startup issue and dead battery, low-power mini-server duty will now migrate to my Inspiron 7577.

Roger Cheng

PC Power Supply Fan Replacement (CWT GPS650S)

While learning electronics by reverse-engineering board schematics, one of my computers started making an intermittent growling noise. I suspect a failing fan bearing. Probably not a big deal, as mechanical things wear, and failure is inevitable. I traced the sound to a Channel Well Technology GPS650S power supply’s internal fan. This computer has a 9th gen Core i7 CPU, which launched in 2019 so this power supply has been running for roughly four years. This is on the short end of PC cooling fan lifespan, but hopefully just bad luck of being on the short end of the bell curve.

Looking on the bright side, I know how to replace a failing fan. So given a choice I prefer this failure mode versus blowing a non-user replaceable fuse or burning up.

Getting past a few “no user serviceable parts inside” and “warranty void if removed” stickers opened up the enclosure to access the 120mm 12VDC fan.

Something’s definitely wrong with the fan, as the label isn’t supposed to get puffy and shiny in the middle like that. This is consistent with friction heat generated by a failing bearing.

Fortunately, the fan seems to be plugged in to the power supply control board with a commodity JST-XH 2-position connector.

Sitting on my shelf are multiple 120mm 12VDC cooling fans that can serve as suitable replacement. One of them even has a JST-XH connector already installed. Judging by the sheet of airflow control plastic on this fan, it was salvaged from another power supply. Probably the the one that blew an inaccessible fuse.

Unfortunately it was not that easy, but that was my own fault. I connected it up to my bench power supply dialed up to 12V DC for a test. It spun up nicely and when I reached over to disconnect power I knocked the fan grill into the fan. The fan, spinning at full speed, dealt with the sudden stop by snapping off a blade. Rendering the fan useless. D’oh!

But I had other fans to spare, including one with an Antec sticker that probably meant it came from the power supply that went up in smoke. It should work just as well, merely a bit less convenient for me because I had to cut off its existing connector and crimp my own JST-XH compatible connector. This time I was more careful with the spin-up test and did not break a blade.

The power supply is now back in action, running quietly with a replacement salvaged fan. And now I have two broken fans on hand: one with a bad bearing and another with a broken blade.

Roger Cheng

Potential Small PC Explorations

I had fun playing with the GMKtec NucBox3, an interesting and capable little PC more affordable than Intel’s NUC product line, naturally with some expected tradeoffs for its lower cost. I learned about these little PCs from a Newegg advertisement and, between the time I ordered one and its arrival, I had a failed USB external drive that I transplanted into a small form factor Dell PC. Computers in these two projects represent a spectrum that I should keep in mind for future project possibilities. Which one I buy would depend on a project’s requirements.

Intel NUC

A genuine Intel NUC would be more expensive than any of the other options below, but sometimes it’s worth spending that money. For example, if I’m building a solution that needs to be reliable, I will pay more for a brand name. Or if I want to design something that can be repeated by others, it’s easier for someone to buy an identical Intel NUC than to find, say, a GMKtec. For this reason: If my Sawppy rover ever changes over to an x86-64 PC ROS brain, the official recommended hardware will be an Intel NUC. (Supplemented with suggestions on what to look for in lower-cost alternatives like the NucBox3.)

Just Below $90

But when we’re feeling adventurous and not particularly motivated to pay for quality or consistency, we can go bargain hunting. Searching for various options, I observed a price floor somewhere in the $80-$90 range. I see an interesting hint of economic factors at play preventing things from much lower than $90, but I don’t know what they might be. (As a point of comparison, Raspberry Pi 4 8GB MSRP is $75.)

Lowest Bidder du Jour

Amazon categorized these products under: “Electronics” > “Computers & Accessories” > “Computers & Tablets” > “Desktops” > “Minis”. Sorting them by price today, I see several options right around $89, roughly 40% discount from the price of a NucBox3. To get to that price point we have to give up many things. For example, this item (*) made some notable tradeoffs:

  • Memory is half the size (4GB vs. 8GB), uses older technology (DDR3 vs. DDR4), and is soldered in never to be upgraded.
  • Storage is half the size (64GB vs 128GB), uses much slower technology (eMMC vs. SATA) and is also permanently soldered. However, it does have a 2.5″ SATA bay, which the NucBox3 does not.
  • CPU is three years older and from a different product generation (Celeron J3455 vs. J4125) and it doesn’t meet hardware requirements for Windows 11.

On the upside, it still meets all my hard requirements for robot brain: 64-bit CPU running x86-64/amd64 instruction set, gigabit Ethernet port, small, lightweight, and might run on battery power. Depending on future project requirements, I may choose these tradeoffs in favor of a <$90 bargain.

Buying Refurbished

Looking at inexpensive PCs on Amazon, I saw a lot of refurbished units. Clicking around a few listings, I learned Amazon had set up an entire department. “Amazon Renewed” is dedicated to refurbished products of all kinds, not just computers. I should definitely keep this in mind as an option. Given my personal experience, I’d restrict my search to refurbished Dell products from their corporate line. Which would still leave me with very many options. Check out these guys, each offered at a few bucks under $90:

  • Optiplex 3040 Micro Desktop (*) are bigger than an Intel NUC, but tiny compared to anything else. Skimming Dell’s manual, I see a 2.5″ SATA bay inside. I also see what looks like a M.2 slot on a picture of its mainboard, but M.2 isn’t called out in the manual as a storage option. I see a gigabit Ethernet port and it accepts power from a DC barrel jack, so there’s a possibility it can be persuaded to run on battery power.
  • Optiplex 790 USFF Desktop (*) are significantly larger. Packing an optical drive on top of a 2.5″ drive bay and AC power supply. No robot battery power for this machine, but dual 2.5″ drives are possible via an optical drive caddy. This could work for TrueNAS replication target if my storage drive is a high capacity 2.5″ laptop hard drive.
  • Optiplex 3020 SFF Slim Desktop (*) is a successor to the Optiplex 960 I repurposed to a TrueNAS replication target, with at least one 3.5″ drive bay and one optical drive bay. This would be my default choice if I need to build another replication target machine.

What if I want a parallel port for LinuxCNC? Sadly, that’s an uncommon enough request I can’t filter on Amazon. But when it comes to refurbished small Dell PCs, Amazon Renewed is not the only game in town. There are plenty of other vendors like PC Liquidations, who offers filtering by parallel port. Resulting in a list of refurbished Dell Optiplex with parallel port starting at, you guessed it, a few dollars under $90. All good options if I want to dedicate a cheap PC to a task, which usually also requires me to set up automatic software updates.

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

Roger Cheng

Good First Impressions of GMKtec NucBox3

It was fun to poke around internal hardware of a tiny PC I wanted to investigate for use as a robot brain. This GMKtec NucBox3 I ordered off Amazon (*) is a more affordable variation on the Intel NUC formula, and its price (significantly lower than Intel’s own NUC) makes me more willing to experiment with it.

Decent PC for Windows 11 Home

But before I take any risk with nonstandard usage, I should verify it worked as advertised. The 128GB SATA SSD came installed with Windows 11 Home edition build 21H2. Upon signing in with my Microsoft account, it started the update process to build 22H2. I assumed the machine came with a license of Windows either embedded in the hardware or otherwise registered. Windows 11 control panel “Activation state” says “Windows is activated with a digital license linked to your Microsoft account” which I found to be ambiguous. I shrugged because I plan to use it as ROS brain and, if so, I’m likely to run Ubuntu instead of Windows. And if I wipe the SATA drive with a fresh installation of Windows 11, it sounds like I can log in with my Microsoft account and retrieve its license.

The more informative aspect of Windows sign-in and registration is letting me get a feel of the machine in its default configuration. All hardware drivers are in place with no question marks in device manager. Normal user interface tasks were responsive and never frustrating, which is better than certain other budget Windows computers I’ve tried. A NucBox3 is a perfectly competent little Windows box for light duty computer use.

One oddity I found with the NucBox3 was the lack of a power-up screen letting me change boot behavior with a keypress. When a PC first powers up, there’s typically a prompt telling me to press F12 to enter a menu to select a boot device, or DEL to enter system setup, etc. Not on a NucBox3, though: we always boot directly into Windows. The only way I found to enter hardware menu was from within Windows: under “Settings”/”System”/”Recovery” we can choose “Advanced startup” to boot into a special Windows menu, where I can select “Advanced Options” and choose “UEFI Firmware Settings”. This is expected to be an infrequent activity most users would never do, so I guess it’s OK for the process to be a convoluted.

UEFI Menu

Once I got into UEFI menu for NucBox3 I was surprised by how many options are listed. Far more than any branded (Dell, etc) computer I’ve seen and even more than hobbyist-focused motherboards.

Some of these options like “Debug Configuration” almost feel like they weren’t supposed to ship in a final product. My hypothesis is that I’m looking at the default full menu of options for a manufacturer using this AMI (American Megatrends, Inc) UEFI firmware. Maybe the manufacturer was expected to trim it down as appropriate for their product, and maybe nobody bothered to do that.

Under the “Chipset” menu we have device configuration for many peripherals absent from this device. They’re marked [Disabled] but the menu option didn’t even need to be here. The final line was also the most surprising: a selection for resistors on I2C buses. On one hand, I’ve never seen a PC’s I2C hardware exposed in any user-visible form before. On the other hand, if I can figure out where SDA/SCL lines are on this motherboard, maybe I can really have some fun. Why bother with a Raspberry Pi or even an ESP32 to bridge I2C hardware if I can attach them directly to this PC?

Ubuntu Server

But all those shiny lights in UEFI menus were just a distraction. What I really want right now is to control boot sequence so I can boot from a USB flash drive to install Ubuntu Server 22.04 LTS. I found I could do it from the “Boot” section of UEFI menu. Ubuntu Server was installed, it worked, and that was no surprise. A computer competent at a full Windows 11 GUI rarely has a problem with text-based network-centric Ubuntu Server, and indeed I had no problems here. For a ROS brain I would want gigabit networking, all four CPU cores, RAM, storage, and USB peripherals. They are all present and accounted for, even sleep mode if I want to put a robot to sleep.

Variable Input Voltage

The next experiment was to see if this computer is tolerant of variable DC supply voltage. On paper it requires 12V DC and the supplied AC adapter was measured at 12.27V DC. I could buy a boost/buck converter that takes a range of input voltages and output a steady 12V (*) but it would be more efficient to run without such conversion if I could get away with it. Since the NucBox3 used a standard 5.5mm OD barrel jack for DC power input, it was easy to wire it up to my bench power supply. I found it was willing to boot up and run from 10VDC to 12.6VDC, the operating voltage range of 3S LiPo battery packs.

Good ROS Brain Candidate

This little computer successfully ran Ubuntu Server on (simulated) battery power. It handily outperforms the Dell 11 3180 I previously bought as ROS brain candidate and is much more compact for easy integration on robot chassis. Bottom line, I have a winner on my hands here!

I’m glad that Newegg advertisement made me aware of an entire ecosystem of inexpensive small PCs. I need to keep this product category in mind as candidates for potential future projects. I have many options to consider, depending on a project’s needs.

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

Roger Cheng

Looking Inside GMKtec NucBox3

I thought the GMKtec NucBox3 looked interesting (at least on paper) as candidate ROS brain, so I ordered one (*) for a closer look despite some skepticism. All pictures on that Amazon listing look perfect, I suspected they were all 3D computer renders instead of photos of an actual product. There’s a chance the actual product looked very different from the listing.

The good news: the product is real and for the most part, as depicted in the listing. I find good fit and finish on its plastic enclosure. There is one downside: fingerprints show up very clearly. I had to wipe down the case pretty aggressively for these pictures and I still see greasy smudges. Well, at least you know these aren’t renders! One instance where oily fingerprint smudges are a feature, not a bug.

I see two brass heat-set inserts on the bottom of the case which will be useful for mounting this little box somewhere. They look very small but this is a small lightweight box so it would probably suffice.

Here we also see where actual product differed from product listing rendering. The company website page for NucBox3 showed an access panel to upgrade memory or storage.

But there’s no such access panel on the real thing, and it’s not clear how to get inside without one. Documents in the box consisted of a minimal warranty card in the box and no instruction manual. No matter, the lack of a convenient access panel or a manual shall not deter me from getting inside for a look.

Hiding fasteners under glued-on rubber feet is a common and effective technique. These four fasteners are not symmetrical so, even though the box is a square, we need to remember correct orientation to reinstall.

Without a convenient access door for upgrades, I wasn’t sure what else would differ from listing picture. I was afraid memory and storage would be soldered-in parts, but I was relieved to find they were standard DDR4 RAM and M.2 2280 SSD as advertised. They’re just a tiny bit harder to access without the panel.

Judging by its M.2 keys, we have the option to upgrade this factory-installed SATA M.2 SSD to a higher-performing NVMe M.2 SSD if needed.

What appears to be empty threaded holes (marked with circles) are actually used to secure the CPU heatsink from the other side. (There’s a fourth one under RAM module and not visible in this image.) Four fasteners (marked with squares) secure the motherboard and must be removed to proceed.

The headphone jack protrudes into the enclosure, so we must tilt the mainboard from the opposite side for removal. But we have to be careful because we are limited by length of WiFi antenna wires.

A block of foam keeps WiFi antenna connectors in place, peeling it back allowed the connectors to be released. The antennae themselves appear to be thin sheets glued to the top of the case, similar to what I’ve salvaged from laptops. How securely were they held? I don’t know. I didn’t try to peel them off.

Freed of WiFi wires, I could flip the mainboard over to see a big heatsink surrounded by connectors. As chock-full of connectors as this product already is, I was surprised to see that there are still several provisions for even more connectors on the circuit board. I’m also very fascinated by connectors used here for USB3, HDMI, and DisplayPort. I usually see them oriented flat against the circuit board as typical of laptop mainboards, but without design pressure to be thin, these connectors are standing upright. This is a tradeoff to fit more connectors on the edge of a circuit board, but each connector must go deeper to obtain the necessary mechanical strength to withstand use.

Looking in from the side, the heatsink appears to have a flat bottom. This is good news if I want to mount a different heatsink on this board, possibly with a fan. The flat bottom means I don’t have to worry about sticking out to make thermal contact with other chips or have to cut a hole to clear protrusions. If I want to mount to the same holes, I will have to drill four holes which unfortunately are irregularly spaced but not an insurmountable challenge. All that said, I’m more likely to just point a fan at this heatsink if heat proves to be a problem.

Using this computer as robot brain also means running it on battery power. Nominal power requirements are listed as 12V up to 3A. My voltmeter measured the factory power adapter output at 12.27V. But what can this thing tolerate? I found this chip directly behind the DC power barrel jack, but a search for DC3905 WK1MEG (or WX1MEG) didn’t turn up anything definitive. Texas Instruments has a LP3905 and Analog inherited Linear Technology’s LT3905. Both chips are designed for DC power handling, but neither footprint matches this chip. This might not even be the power management chip, I’m only guessing based on its proximity to the DC barrel jack.

As far as I know, the highest voltage requirement on this PC are USB ports at 5V. On the assumption that nothing on this machine actually needs 12V, then all power conversion are buck converters to lower voltage levels. If true, then this little box should be OK running directly on 3S LiPo power (Three lithium-polymer battery cells in series) which would range from 12.6V fully charged to 11.1V nominal to 10V low power cutoff. I’ll use the power brick that came in the box to verify everything works before testing my battery power hypothesis.

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

Roger Cheng

SATA Optical to 2.5″ Drive Adapter

I dusted off an old Dell Optiplex 960 for use as my TrueNAS replication backup target. The compact chassis had a place for my backup storage 8TB 3.5″ HDD extracted from a failed USB enclosure, which is good. But I also need a separate drive for Ubuntu operating system, and that’s where I ran into problems. There was an empty 3.5″ bay and a SATA data socket available on the motherboard, but the metal mounting bracket was missing, and power supply had no more SATA power plugs.

As an alternative plan, I thought I would repurpose the optical drive’s location. Not just its SATA data and power plugs, but I could also repurpose physical mounting bracket with an optical drive shaped caddy for a 2.5″ SATA drive. (*) It wasn’t a perfect fit but that was my own fault for ordering the wrong size.

Examining the caddy after I opened its package, I saw this oddly bent piece of sheet metal. Comparing against the DVD drive, I don’t think it’s supposed to bend like that. I can’t tell if it was damaged at the factory or during shipping, either way metal was thin and easy to bend back into place.

Also comparing against the DVD drive, I realized I bought the wrong size. It didn’t occur to me to check to see if there were multiple different sizes for laptop DVD drives. I bought a 9.5mm thick caddy (*) when I should have bought something thicker possibly this 12.7mm thick unit.(*) Oh well, I have this one in hand now and I’m going to try to make it work.

To install this caddy in an Optiplex 960 chassis, I need to reuse the sheet metal tray currently attached to the DVD drive.

One side fit without problems, but the other side didn’t fit due to mismatched height. This is my own fault.

There’s a mismatch in width as well, I’m not sure this was my fault. I understand the different form factors to be the same width so this part should have lined up. Oh well, at least it is easier to deal with a ~1mm too narrow adapter because one ~1mm too wide wouldn’t fit at all.

There were slots to take the DVD drive’s faceplate. This is for aesthetics so we don’t leave a gaping hole, the eject button wouldn’t work as it is no longer a DVD drive. Unfortunately, faceplate mounting slots didn’t match up, either. This might also be a function of the wrong height, but I’m skeptical. I ended up using the generic faceplate that came with the caddy.

Forcing everything to fit results in a caddy mounted crookedly.

Which resulted in a crooked facade.

Aesthetically speaking this is unfortunate, I should have bought a taller caddy (*) but functionally this unit works fine. The SSD is securely mounted in the caddy, which is now securely mounted to the chassis. And even more importantly, SATA power and data communication worked just fine, allowing me to install Ubuntu Server 22.04 LTS on an old small SSD inside the caddy. And about that old SSD… freeing it up for use turned out to be its own adventure.

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

Roger Cheng

Dusting Off Dell Optiplex 960 SFF PC

After two years of use, my USB3 external 8TB backup drive stopped responding as an external disk. I took apart its enclosure and extracted a standard 3.5″ hard disk drive which seems OK in perfunctory testing. In order to continue using it for TrueNAS replication backup, I’ll need another enclosure. I briefly contemplated getting an USB3 SATA enclosure that takes 3.5″ drives (*) but I decided to use an entire computer as its enclosure: I have an old Dell Optiplex 960 SFF (small form factor) PC collecting dust and it would be more useful as my TrueNAS replication backup machine.

Dell’s Optiplex line is aimed at corporate customers, which meant it incorporated many design priorities that weren’t worth my money to buy new. But those designs also tend to live well past their first lives, and I have bought refurbished corporate Dells before. I’ve found them to be sturdy well-engineered machines that, on the secondhand market, is worth a small premium over generic refurbished PCs.

There’s nothing garish with exterior appearance of an Optiplex, just the computer equivalent of professional office attire. This particular machine is designed to be a little space-efficient box. Office space costs money and some companies decide compactness is worth paying for. Building such a compact box required using parts with nonstandard form factors. For a hobbyist like me, not being able to replace components with generic standard parts is a downside. For the corporate IT department with a Dell service contract, the ease of diagnosis and servicing is well worth the tradeoff.

This box is just as happy sitting horizontally as vertically, with rubber feet to handle either orientation.

Before it collected dust on my shelf, this computer collected dust on another maker’s shelf. I asked for it sometime around the time I started playing with LinuxCNC. I saw this computer had a built-in parallel port, so I would not need an expansion card. (Or I can add a card for even more control pins.) The previous owner said “Sure, I’m not doing anything with it, take it if you will do cool things with it.” Unfortunately, my LinuxCNC investigation came to a halt due to pandemic lockdown and I lost access to that space. TrueNAS replication target may not be as cool as my original intention for this box, but at least it’s better than collection dust.

Even though the chassis is small, it has a lot of nice design features. The row of “1 2 3 4” across the front are diagnostics LEDs. They light up in various combinations during initial boot-up so, if the computer fails to boot corporate IT tech support can start diagnosing failure before even opening up the box.

Which is great, because opening up the box might be hindered by a big beefy lock keeping the side release lever from sliding.

And if we get past the lock and open the lid, we trip the chassis intrusion detection switch. I’ve seen provision for chassis intrusion detection in my hobbyist-grade motherboards, but I never bothered to add an actual intrusion switch to any of my machines. Or a lock, for that matter.

Once opened I find everything is designed to be worked on without requiring specific tools. This chassis accommodates two half-height expansion cards: One PCI and one PCI-Express. On my PCs, expansion endplates are held by small Philips-head screws. On this PC, endplates are retained by this mechanism.

A push on the blue button releases a clamp for access to these endplates.

Adjacent to those expansion slots is a black plastic cage for 3.5″ Hard drive.

Two blue metal clips release the cage to flip open, allowing access to the hard drive. This drive was intended to be the only storage device hosting operating system plus all data. I plan to install my extracted 8TB backup storage drive in this space, which needs to be a separate drive from the operating system drive, so I need to find another space for a system drive.

Most of the motherboard is visible after I flipped the HDD cage out of the way. I see three SATA sockets. One for the storage HDD, one for the DVD drive, and an empty one I can use for my system drive. Next to those slots is a stick of DDR2 RAM. (I’m quite certain Corsair-branded RAM is not original Dell equipment.) Before I do anything else with this computer, I will need to replace the CR2032 coin cell timekeeping battery.

A push on the blue-stickered sheet metal button released the DVD drive. Judging by scratches, this DVD drive has been removed and reinstalled many times.

Putting the DVD drive aside, I can see a spare 3.5″ drive bay underneath. This was expected because we could see a 3.5″ blank plate in the front of this machine, possibly originally designed for a floppy disk drive. The good news is that this bay is empty and available, the bad news is that a critical piece of hardware is missing: This chassis is designed to have a sheet metal tray for installing a 3.5″ drive, which is not here.

I can probably hack around the missing bracket with something 3D-printed or even just double-sided tape. But even if I could mount a small SSD in here, there are no spare SATA power connector available for it. This is a problem. I contemplated repurposing the DVD drive’s power and data cables for a SSD and found adapters cables for this purpose. (*) But under related items, I found a product I didn’t even know existed: an optical-to-hard drive adapter (*) that doesn’t just handle the power and data connectors, it is also a mechanical fit into the optical drive’s space!

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

Roger Cheng

Window Shopping: GMKtec NucBox3 Mini PC

A Newegg advertisement sent me down a rabbit hole of tiny little desktop PCs with full x86-64 processors. I knew about Intel’s NUC, but I hadn’t realized there was an entire product ecosystem of such small form factor machines built by other manufacturers. The one that originally caught my attention was distributed by several different companies under different names, I haven’t figured out who made it. But that exploration took me to GMKtec which is either their manufacturer, or a distributor with a sizable collection of similar products built by different manufacturers. The product that originally caught my attention is listed as their “NucBox5” (company website listing and Amazon link *) but I actually found their “NucBox3” (company website listing and Amazon link *) to be a more interesting candidate for my Sawppy Rover’s ROS brain. Both products have a Gigabit Ethernet wired networking port that I demand for resistance against RF interference, but beyond that, their respective designs differ wildly:

First the bad news: the NucBox 3 has an older CPU, the Celeron J4125 instead of the Celeron N5105. But comparing them side-by-side, it looks like I’d be giving up less than 10% of peak CPU performance. There is a huge (~50%) drop in GPU performance, but that doesn’t matter to Sawppy because most of the time its brain wouldn’t even have a screen attached.

A longer list of good stuff balances out the slower CPU:

  • RAM on the NucBox 3 is a commodity DDR4 laptop memory module. That can be easily upgraded if needed, unlike the soldered-in memory on the NucBox 5.
  • They both use M.2 SSDs for storage, but the NucBox 3 accommodates popular 2280 form factor instead of a less common 2245 size used by NucBox 5.
  • The SSD advantage was possible because NucBox 3 has a different shape: is wider and deeper than a NucBox 5, but not as tall. Designed for installation on a VESA 100×100 mount, it will be easier to bolt onto a rover chassis.
  • Officially, NucBox 3 is a fan-less passively cooled machine whereas the NucBox 5 has a tiny little cooling fan inside. (Which I expect to be loud, as tiny cooling fans tend to be.) Given that these are both 10W chips, I doubt NucBox 3 has a more effective cooling solution, I think it is more likely that the design just lets the chip heat up and throttle itself to stay within thermal limits. This would restrict its performance in stock form, but it also means it’ll be easy for me to hack up a quiet cooling solution if necessary.
  • NucBox 5 accepts power via USB-C, which is getting easier and easier to work with. I foresaw no problems integrating it with battery power onboard a Sawppy rover. But the NucBox 3 has a generic 5.5mm barrel jack for DC input power, and I think that’ll be even easier.

A NucBox3 costs roughly 80% of a NucBox5 for >90% of the performance, plus all of the designed tradeoff listed above are (I feel) advantages in favor of the NucBox3. I’m sold! I placed an order (*) and look forward to playing with it once it arrives.

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

Roger Cheng

Window Shopping: Mystery Mini PC of Many Names

An interesting item came to my attention via Newegg marketing mailing list for discounts: an amazingly tiny Windows PC. My attention was captured by listing picture showing its collection of hardware ports. Knowing the size of an Ethernet port and HDMI port we can infer this is an itty-bitty thing. Newegg’s specific sale item was generically named “Mini PC” with an asking price of $200. I’m not entirely sure the thing is real: all the images look perfect enough I couldn’t tell if they’re 3D renderings or a highly retouched product photos.

I looked at the other listings by the same vendor “JOHNKANG” and saw several other generically named devices ranging from laptops to external monitors. There were no other similar products, so I think JOHNKANG is a distributor and not the manufacturer of this palm-sized wonder. If JOHNKANG is a US distributor for such merchandise, I guessed they probably have an Amazon listing as well. Sure enough, they have it listed on Amazon also at $200(*) at time of writing. Unlike the Newegg listing, the Amazon listing included this exploded-view diagram showing internals and capabilities.

That’s… pretty darned good for $200! With an Intel Celeron N5105 processor, I see a machine roughly equivalent to capabilities of a budget laptop but without the keyboard, screen, or battery. Storage size is serviceable at 256GB and can be swapped out with another M.2 SSD, though in a less common 2242 format which is shorter than the popular 2280. Its 8GB of RAM are soldered and not easily expandable, but 8GB is more than sufficient for this price point.

A few features distinguish this tiny PC from equivalent-priced laptops, starting with its dual HDMI port where laptops only have one. That might be important for certain uses, but I’m more interested in its wired Gigabit Ethernet port and that it runs on USB-C power input. This machine appears to check off all of my requirements for a candidate Sawppy Rover brain. It’s a pretty good candidate for running ROS slotting just below an Intel NUC in capability but compensates for that with a lower price and smaller physical size. Heck, at this size it is starting to compete with Raspberry Pi and might even fit in a Micro Sawppy.

I found no make or model number listed, which is consistent with a distributor that really doesn’t want us to comparison shop against anyone else who might be distributing the same product for less money. If I want hard details, I might have to buy one and look over the hardware for hints as to who built it. Still, searching for “Mini PC” and “MiniPC” with N5105 CPU found this eBay listing of a used unit with Rateyuso branding. Then I found this AliExpress listing with ZX01 as model name. That AliExpress listing is a mess, showing pictures of several other different mini PCs. Not confidence inspiring and definitely turned me off of buying from that vendor. However, the “ZX01” model name was useful because it led me to this page, which linked to a Kickstarter project that has apparently been taken down due to intellectual property dispute.

Performing an image search using the suspiciously perfect picture/render found the GMKtec Nucbox5(*) which appears to be the same product but with “GMKtec” stamped on top. Looking at the Amazon storefront for GMKtec (*) I see many other small form factor PCs without any family resemblance between their industrial designs. My hypothesis is that GMKtec is a distributor as well, but they have built up a collection of products from different manufacturers and that’s why they all look different. I thought this was encouraging. It implies experience and knowledge with the ecosystem of tiny PCs, offering a breadth of products each making a different tradeoff. I looked over their roster and found one more to my taste.

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

Roger Cheng

High Power 600W Power Supply (HP1-J600GD-F12S)

Along with the “keyboard is broken” laptop, I was also asked to look into a mid-tower PC that would no longer turn on. I grabbed a power supply I had on hand and plugged it into the motherboard, which happily powered up. Diagnosis: dead power supply. I bought a new power supply for the PC to bring it back to life, now it’s time to take apart the dead power supply to see if I can find anything interesting. Could it be as easy as a popped circuit breaker or a blown fuse?

According to the label, the manufacturer has the impossibly unsearchable name of “High Power”. Fortunately, the model number HP1-J600GD-F12S is specific enough to find a product page on the manufacturer’s site. The exact model string also returned a hit for a power supply under Newegg’s house brand Rosewill, implying the same device was sold under Newegg’s own name. Amusingly, Newegg’s Rosewill product listing included pictures with “High Power” embossed on the side.

If there is a user-replaceable fuse or a user-accessible circuit breaker, they should be adjacent to the power socket and switch. I saw nothing promising at the expected location or anywhere else along the exterior.

Which meant it was time to void the warranty.

Exterior enclosure consisted of two pieces of sheet metal each bent into a U shape and held together with four fasteners. Once pried apart, I had to cut a few more zip-ties holding the cooling fan power wire in place before I could unplug it to get a clear view at the interior. Everything looks clean. In fact, it looked too clean — either this computer hadn’t been used very much before it blew, or it lived in a location with good air filtration to remove dust.

Still on the hunt for a circuit breaker or a fuse, I found the standard boilerplate fuse replacement warning. Usually, this kind of language would be printed immediately adjacent to a user-serviceable fuse. But getting here required breaking the warranty seal and none of the adjacent components looked like a fuse to me.

Disassembly continued until I could see the circuit traces at the bottom of the board. Getting here required some destructive cutting of wires, so there’s no bringing this thing back online. Perhaps someone with better skills could get here nondestructively but I lacked the skill or the motivation to figure things out nicely. I saw no obviously damaged components or traces on this side, either. But more importantly, now I could see that 120V AC line voltage input wire is connected to a single wire. That must lead to the fuse.

Turning the board back over, I see the line voltage input wire (brown) connected to a black wire that led to a cylinder covered in heat-shrink tubing and held in place by black epoxy. The shape of that cylinder is consistent with a fuse. The heat-shrink and epoxy meant this is really not intended to be easily replaced.

Once unsoldered, I could see the electronic schematic symbol for fuse printed on the circuit board. The “F” in its designation “F1” is consistent with “Fuse”, as do the amperage/voltage ratings listed below. This fuse is a few centimeters away from the caution message I noticed earlier, which was farther away than I had expected. My multi-meter showed no continuity across this device, so indeed the fuse has blown. I cut off the heat-shrink hoping to see a burnt filament inside a glass tube, but this fuse didn’t use a glass tube.

I started this teardown wondering if it was “as easy as a popped circuit breaker or a blown fuse”. While it was indeed a blown fuse, a nondestructive replacement would not have been easy. I don’t know why the fuse on this device was designed to be so difficult to access and replace, but I appreciate it is far better to blow a fuse than for a failing power supply to start a fire.

Roger Cheng

Windows PC Keyboard Beeps Instead of Types? Turn Off “Filter Keys”

A common side effect of technical aptitude is the inevitable request “Can you help me with my computer?” Whether this side effect is an upside or downside depends on the people involved. Recently I was asked to help resurrect a computer that had been shelved due to “the keyboard stopped working.”

Before I received the hardware, I was told the computer was an Asus T300L allowing me to do a bit of research beforehand. This is a Windows 8 era touchscreen tablet/laptop convertible along the lines of a Microsoft Surface Pro or the HP Split X2. This added a twist: the T300L keyboard base not only worked while docked, but it could also continue working as a wireless keyboard + touchpad when separated from the screen. This could add a few hardware-related variables for me to investigate.

When I was finally presented with the machine, I watched the owner type their Windows login password using the keyboard. “Wait, I thought you said the keyboard didn’t work?” “Oh, it works fine for the password. It stops working after I log in.”

Ah, the hazard of imprecision of the English language. When I was first told “keyboard doesn’t work” my mind went to loose electrical connections. And when I learned of the wireless keyboard + touchpad base, I added the possibility of wireless settings (device pairing, etc.) I had a hardware-oriented checklist ready and now I can throw it all away. If the keyboard worked for typing in Windows password, the problem is not hardware.

Once the Windows 8 desktop was presented, I could see what “keyboard stopped working” meant: every keypress resulted in an audible beep but no character typed on screen. A web search with these symptoms found this Microsoft forum thread titled “Keyboard Beeps and won’t type” with the (apparently common) answer to check Windows’ Ease of Access center. I made my way to that menu (as the touchscreen worked fine) and found that Filter Keys were turned on.

Filter Keys is a feature that helps users living with motor control challenges that result in shaky hands. This could result in pressing a key multiple times when they only meant to press a key once or jostling adjacent keys during that keypress. Filter Keys slow the computer’s keyboard response, so they only register long and deliberate presses as a single action. Rapid tap and release of a key — which is what usually happens in mainstream typing action — are ignored and only a beep is played. Which is great, if the user knew how to use Filter Keys and intentionally turned it on.

In this case, nobody knows how this feature got turned on for this computer, but apparently it was not intentional. They didn’t recognize the symptoms of Filter Keys being active. Lacking that knowledge, they could only communicate their observation as “the keyboard stopped working.” I guess that description isn’t completely wrong, even if it led me down the wrong path in my initial research. Ah well. Once Filter Keys were turned off, everything is fine again.

Roger Cheng

MageGee Wireless Keyboard (TS92)

In the interest of improving ergonomics, I’ve been experimenting with different keyboard placements. I have some ideas about attaching keyboard to my chair instead of my desk, and a wireless keyboard would eliminate concerns about routing wires. Especially wires that could get pinched or rolled over when I move my chair. Since this is just a starting point for experimentation, I wanted something I could feel free to modify as ideas may strike. I looked for the cheapest and smallest wireless keyboard and found the MageGee TS92 Wireless Keyboard (Pink). (*)

This is a “60% keyboard” which is a phrase I’ve seen used two different ways. The first refers to physical size of individual keys, if they were smaller than those on a standard keyboard. The second way refers to the overall keyboard with fewer keys than the standard keyboard, but individual keys are still the same size as those on a standard keyboard. This is the latter: elimination of numeric keypad, arrow keys, etc. means this keyboard only has 61 keys, roughly 60% of standard keyboards which typically have 101 keys. But each key is still the normal size.

The lettering on these keys are… sufficient. Edges are blurry and not very crisp, and consistency varies. But the labels are readable so it’s fine. The length of travel on these keys are pretty good, much longer than a typical laptop keyboard, but the tactile feedback is poor. Consistent with cheap membrane keyboards, which of course this is.

Back side of the keyboard shows a nice touch: a slot to store the wireless USB dongle so it doesn’t get lost. There is also an on/off switch and, next to it, a USB Type-C port (not visible in picture, facing away from camera) for charging the onboard battery.

Looks pretty simple and straightforward, let’s open it up to see what’s inside.

I peeled off everything held with adhesives expecting some fasteners to be hidden underneath. I was surprised to find nothing. Is this thing glued together? Or held with clips?

I found my answer when I discovered that this thing had RGB LEDs. I did not intend to buy a light-up keyboard, but I have one now. The illumination showed screws hiding under keys.

There are six Philips-head self-tapping plastic screws hidden under keys distributed around the keyboard.

Once they were removed, keys assembly easily lifted away to expose the membrane underneath.

Underneath the membrane is the light-up subassembly. Looks like a row of LEDs across the top that shines onto a clear plastic sheet acting to diffuse and direct their light.

I count five LEDs, and the bumps molded into clear plastic sheet worked well to direct light where the keys are.

I had expected to see a single data wire consistent with NeoPixel a.k.a. WS2812 style of individually addressable RGB LEDs. But label of SCL and SDA implies this LED strip is controlled via I2C. If it were a larger array I would be interested in digging deeper with a logic analyzer, but a strip of just five LEDs isn’t interesting enough to me so I moved on.

Underneath the LED we see the battery, connected to a power control board (which has both the on/off switch and the Type-C charging port) feeding power to the mainboard.

Single cell lithium-polymer battery with claimed 2000mAh capacity.

The power control board is fascinating, because somebody managed to lay everything out on a single layer. Of course, they’re helped by the fact that this particular Type-C connector doesn’t break out all of the pins. Probably just a simple voltage divider requesting 5V, or maybe not even that! I hope that little chip at U1 labeled B5TE (or 85TE) is a real lithium-ion battery manage system (BMS) because I don’t see any other candidates and I don’t want a fiery battery.

The main board has fewer components but more traces, most of which led to the keyboard membrane. There appears to be two chips under blobs of epoxy, and a PCB antenna similar to others I’ve seen designed to work on 2.4GHz.

With easy disassembly and modular construction, I think it’ll be easy to modify this keyboard if ideas should strike. Or if I decide I don’t need a keyboard after all, that power subsystem would be easy (and useful!) for other projects.

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

Roger Cheng

Old OCZ SSD Reawakened and Benchmarked

In the interest of adding 3.5″ HDD bays to a tower case, along with cleaning up wiring to power them, I installed a Rosewill quad hard drive cage where a trio of 5.25″ drive bays currently sit open and unused. It mostly fit. To verify that all drive cage cable connections worked with my SATA expansion PCIe card (*) I grabbed four drives from my shelf of standby hardware. When installing them in the drive cage, I realized I made a mistake: one of the drives was an old OCZ Core Series V2 120GB SSD that had stopped responding to its SATA input. I continued installation anyway because I thought it would be interesting to see how the SATA expansion card handled a nonresponsive drive.

Obviously, because today intent was to see an unresponsive drive, Murphy’s Law stepped in and foiled the plan: when I turned on the computer, that old SSD responded just fine. Figures! I don’t know if there was something helpful in the drive cage, or the SATA card, or if something was wrong with the computer that refused to work with this SSD years ago. Whatever the reason, it’s alive now. What can I do with it? Well, I can fire up the Ubuntu disk utility and get some non-exhaustive benchmark numbers.

Average read rate 143.2 MB/s, write 80.3 MB/s, and seek of 0.22 ms. This is far faster than what I observed by using the USB2 interface, so I was wrong earlier about the performance bottleneck. Actual performance is probably lower than this, though. Looking at the red line representing write performance, we can see it started out strong but degraded at around 60% of the way through the test and kept getting worse, probably the onboard cache filling up. If this test ran longer, we might get more and more of the bottom end write performance of 17 MB/s.

How do these numbers compare to some contemporaries? Digging through my pile of hardware, I found a Samsung ST750LM022. This is a spinning-platter laptop hard drive with 750GB capacity.

Average read 85.7 MB/s, write 71.2 MB/s, and seek of 16.77 ms. Looking at that graph, we can clearly see degradation in read and write performance as the test ran. We’d need to run this test for longer before seeing a bottom taper, which may or may not be worse than the OCZ SSD. But even with this short test, we can see the read performance of a SSD does not degrade over time, and that SSD has a much more consistent and far faster seek time.

That was interesting, how about another SSD? I have an 120GB SSD from the famed Intel X25-M series of roughly similar vintage.

Average read 261.2 MB/s, write 106.5 MB/s, seek 0.15 ms. Like the OCZ SSD, performance took a dip right around the 60% mark. But after it did whatever housekeeping it needed to do, performance level resumed at roughly same level as earlier. Unlike the OCZ, we don’t see as much of a degradation after 60%.

I didn’t expect this simple benchmark test to uncover the full picture, as confirmed after seeing this graph. By these numbers, the Intel was around 30% better than the OCZ. But my memory says otherwise. In actual use as a laptop system drive, the Intel was a pleasure and the OCZ was a torture. I’m sure these graphs are missing some important aspects of their relative performance.

Since I had everything set up anyway, I plugged in a SanDisk SSD that had the advantage of a few years of evolution. In practical use, I didn’t notice much of a difference between this newer SanDisk and the old Intel. How do things look on this benchmark tool?

Average read 478.6 MB/s, write 203.4 MB/s, seek 0.05 ms. By these benchmarks, the younger SanDisk absolutely kicked butt of an older Intel with at least double the performance. But that was not borne out by user experience as a laptop drive, it didn’t feel much faster.

Given that the SanDisk benchmarked so much faster than the Intel (but didn’t feel that way in use) and OCZ benchmarked only slightly worse than the Intel (but absolutely felt far worse in use) I think the only conclusion I can draw here is: Ubuntu Disk Utility built-in benchmarking tool does not reflect actual usage. If I really wanted to measure performance details of these drives, I need to find a better disk drive benchmarking tool. Fortunately, today’s objective was not to measure drive performance, it was only to verify all four bays of my Rosewill drive cage were functional. It was a success on that front, and I’ll call it good for today.

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