Nixie Clock Failure Analysis, [Dalibor Farný] Style

We’ve become sadly accustomed to consumer devices that seem to give up the ghost right after the warranty period expires. And even when we get “lucky” and the device fails while it’s still covered, chances are that there will be no attempt to repair it; the unit will be replaced with a new one, and the failed one will get pitched in the e-waste bin.

Not every manufacturer takes this approach, however. When premium quality is the keystone of your brand, you need to take field failures seriously. [Dalibor Farný], maker of high-end Nixie tubes and the sleek, sophisticated clocks they plug into, realizes this, and a new video goes into depth about the process he uses to diagnose issues and prevent them in the future.

One clock with a digit stuck off was traced to via failure by barrel fatigue, or the board material cracking inside the via hole and breaking the plated-through copper. This prompted a board redesign to increase the diameter of all the vias, eliminating that failure mode. Another clock had a digit stuck on, which ended up being a short to ground caused by pin misalignment; when the tube was plugged in, the pins slipped and scraped some solder off the socket and onto the ground plane of the board. That resulted in another redesign that not only fixed the problem by eliminating the ground plane on the upper side of the board, but also improved the aesthetics of the board dramatically.

As with all things [Dalibor], the video is a feast for the eyes with the warm orange glow in the polished glass and chrome tubes contrasting with the bead-blasted aluminum chassis. If you haven’t watched the “making of” video yet, you’ve got to check that out too.

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[Mr. Carlson] Fixes A Fridge

A dead refrigerator is an occurrence determined to frustrate any homeowner. First there’s the discovery of hundreds of dollars in spoiled food, and then the cost of a repair call and the delay of the inevitable wait for parts. It’s clear to see why a hacker like [Mr. Carlson] would seek another way.

Now, normally a fridge repair video would by unlikely fodder for a Hackaday article. After all, there’s generally not much to a fridge, and even with the newer microprocessor-controlled units, diagnosis and repair are usually at the board-level. But [Mr. Carlson] has had this fridge since 2007, and he’s got some history with it. An earlier failure was caused by the incandescent interior lights welding relay contacts closed thanks to huge inrush currents when starting the cold filaments. That left the light on all the time, heating the interior. His fix was a custom solid-state relay using zero-crossing opto-isolators to turn the bulbs on or off only when the AC power was at a minimum.

That repair kept things going for years, but when the latest issue occurred, [Mr. Carlson] took a different tack. He assumed that a board that has been powered 24-7 for the last twelve years is likely to have a bad capacitor or two. He replaced all the caps, threw in a few new relays to be on the safe side, and powered the fridge back up. It whirred back to life, ready for another decade or so of service.

Kudos to [Mr. Carlson] for his great repair tips and his refusal to surrender. The same thing happened when his solder sucker started to give up the ghost and he fixed it by adding a variable-frequency drive.

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Hackaday Links: August 25, 2019

Doesn’t the Z-axis on 3D-printers seem a little – underused? I mean, all it does is creep up a fraction of a millimeter as the printer works through each slice. It would be nice if it could work with the other two axes and actually do something interesting. Which is exactly what’s happening in the nonplanar 3D-printing methods being explored at the University of Hamburg. Printing proceeds normally up until the end, when some modifications to Slic3r allow smooth toolpaths to fill in the stairsteps and produce a smooth(er) finish. It obviously won’t work for all prints or printers, but it’s nice to see the Z-axis finally pulling its weight.

If you want to know how something breaks, best to talk to someone who looks inside broken stuff for a living. [Roger Cicala] from spends a lot of time doing just that, and he has come to some interesting conclusions about how electronics gear breaks. For his money, the prime culprit in camera and lens breakdowns is side-mounted buttons and jacks. The reason why is obvious once you think about it: components mounted perpendicular to the force needed to operate them are subject to a torque. That’s a problem when the only thing holding the component to the board is a few SMD solder pads. He covers some other interesting failure modes, too, and the whole article is worth a read to learn how not to design a robust product.

In the seemingly neverending quest to build the world’s worst Bitcoin mining rig, behold the 8BitCoin. It uses the 6502 processor in an Apple ][ to perform the necessary hashes, and it took a bit of doing to port the 32-bit SHA256 routines to an 8-bit platform. But therein lies the hack. But what about performance? Something something heat death of the universe…

Contributing Editor [Tom Nardi] dropped a tip about a new online magazine for people like us. Dubbed Paged Out!, the online quarterly ‘zine is a collection of contributed stories from hackers, programmers, retrocomputing buffs, and pretty much anyone with something to say. Each article is one page and is formatted however the author wants to, which leads to some interesting layouts. You can check out the current issue here; they’re still looking for a bunch of articles for the next issue, so maybe consider writing up something for them – after you put it on, of course.

Tipline stalwart [Qes] let us know about an interesting development in semiconductor manufacturing. Rather than concentrating on making transistors smaller, a team at Tufts University is making transistors from threads. Not threads of silicon, or quantum threads, or threads as a metaphor for something small and high-tech. Actual threads, like for sewing. Of course, there’s plenty more involved, like carbon nanotubes — hey, it was either that or graphene, right? — gold wires, and something called an ionogel that holds the whole thing together in a blob of electrolyte. The idea is to remove all rigid components and make truly flexible circuits. The possibilities for wearable sensors could be endless.

And finally, here’s a neat design for an ergonomic utility knife. It’s from our friend [Eric Strebel], an industrial designer who has been teaching us all a lot about his field through his YouTube channel. This knife is a minimalist affair, designed for those times when you need more than an X-Acto but a full utility knife is prohibitively bulky. [Eric’s] design is a simple 3D-printed clamshell that holds a standard utility knife blade firmly while providing good grip thanks to thoughtfully positioned finger depressions. We always get a kick out of watching [Eric] design little widgets like these; there’s a lot to learn from watching his design process.

Thanks to [JRD] and [mgsouth] for tips.

Neopixels Recreate Pinball Color Wheel That Never Was

With what pinball aficionados pay for the machines they so lovingly restore, it’s hard to imagine that these devices were once built to a price point. They had to make money, and whatever it took to attract attention and separate the customer from their hard-earned coins was usually included in the design. But only up to a point.

Take the 1967 Williams classic, “Magic City.” As pinball collector [Mark Gibson] explains it, the original design called for a rotating color filter behind a fountain motif in the back-glass, to change the color of the waters in an attractive way. Due to its cost, Williams never implemented the color wheel, so rather than settle for a boring fountain, [Mark] built a virtual color wheel with Neopixels. He went through several prototypes before settling on a pattern with even light distribution and building a PCB. The software is more complex than it might seem; it turns out to require a little color theory to get the transitions to look good, and it also provides a chance for a little razzle-dazzle. He implemented a spiral effect in code, and added a few random white sparkles to the fountain. [Mark] has a few videos of the fountain in action, and it ended up looking quite nice.

We’ve featured [Mark]’s pinball builds before, including his atomic pinball clock, We even celebrated his wizardry in song at one point.

Liquid Damaged MacBook Saved With A Keen Eye

Even among those of us with a penchant for repairing electronics, there are some failures which are generally considered too severe to come back from. A good example is liquid damage in a laptop; with so many components and complex circuits crammed into such a small area, making heads or tails of it once the corrosion sets in can be a real nightmare. Especially in the case of an older laptop, the conventional wisdom is to try and recover your files and then buy a new one.

But as we’ve come to learn, [Jason Gin] is not a man who often finds himself concerned with conventional wisdom. After finding an older MacBook with suspected liquid damage, he decided to see what it would take to restore it to working order. According to a note on the device, the screen was dead, the USB ports were fried, the battery didn’t take a charge, and it wouldn’t boot. No problem then, should be easy.

Upon opening up the circa-2012 laptop, [Jason] found the machine to be riddled with corrosion. We’re not just talking surface gunk either. After giving everything a good cleaning with isopropyl alcohol, the true extent of the damage became clear. Not only had traces on the PCB rotted away, but there were many components that were either damaged or missing altogether. Whatever spilled inside this poor Mac was clearly some nasty stuff.

[Jason] used OpenBoardView to pull up schematics and diagrams of the motherboard, and started the arduous task of visually comparing them to his damaged unit. In some areas, the corrosion was so bad he still had trouble locating the correct traces and pads. But with time and effort, he was able to start probing around and seeing what components had actually given up the ghost.

For the USB ports it ended up being a bad 10-microfarad ceramic capacitor, but for the LCD, he ended up having to replace the entire backlight driver IC. The prospect of working on this tiny BGA-25 device might have been enough for some to throw in the towel, but compared to the hand-soldered magnet wire repairs required elsewhere on the board, [Jason] says the installation of the new LP8550 chip was one of the easier aspects of the whole operation.

The write-up is a great read if you like a good repair success story, and we especially like the way he documented his diagnosis and resulting work on a per-system basis. It makes it much easier to understand just how many individual fires [Jason] had to put out. But if you’re more interested in feats of steady-handed soldering, check out his recent project to add a PCI-E slot to the Atomic Pi.

Sprucing Up A Bell & Howell Model 34 Oscilloscope

We’ll admit it, in an era when you can get a four channel digital storage oscilloscope with protocol decoding for a few hundred bucks, it can be hard not to see the appeal of analog CRT scopes from decades past. Sure they’re heavy, harder to use, and less capable, but they just look so cool. Who could say no to having one of these classic pieces of gear on their bench?

[Cody Nybo] certainly couldn’t. Despite the fact that he already has a digital scope, he couldn’t pass up the chance to add a Bell & Howell Schools Model 34 from circa 1973 to his collection. It needed a bit of TLC before it could be brought back into service, but now it’s all fixed up and ready to put in some work. Not bad for a piece of gear with nearly a half-century on the clock.

The restoration of the Model 34 was aided by the fact that [Cody] got the original manual and schematics for the scope in the deal, which he was kind enough to scan and upload for the rest of the class to enjoy. Those of you who have worked on older electronics can already guess where the scope needed the most love: all the capacitors needed to be swapped out for fresh ones. He also found a few resistors that were out of spec, and the occasional bad solder joint here and there.

Even if you’re not looking to repair your own middle-aged oscilloscope, his pictures of the inside of Model 34 are fascinating. The scope was sold as a kit, so the construction is surprisingly simple and almost entirely point-to-point. Of course, there’s something of a trade-off at work: [Cody] says it won’t display much more than 2.5 MHz before things start getting wonky. But then again, that’s a more than reasonable frequency ceiling for audio work and most hobbyist projects.

Oscilloscopes have come a long way since the days when they had to draw out their readings on a piece of paper. While newer devices have all but buried the classic analog scope, a beauty like this would still have a place of honor in our lab.

Lighting Tech Dives Into The Guts Of Laser Galvanometers

There’s something magical about a laser light show. Watching that intense beam of light flit back and forth to make shapes and patterns, some of them even animated, is pretty neat. It leaves those of us with a technical bent wondering just exactly how the beam is manipulated that fast.

Wonder no more as [Zenodilodon], a working concert laser tech with a deep junk bin, dives into the innards of closed-loop galvanometers, which lie at the heart of laser light shows. Galvos are closely related to moving-coil analog meters, which use the magnetic field of a coil to deflect a needle against spring force to measure current. Laser galvos, on the other hand, are optimized to move a lightweight mirror back and forth, by tiny amounts but very rapidly, to achieve the deflection needed to trace out shapes.

As [Zeno] explains in his teardown of some galvos that have seen better days, this means using a very low-mass permanent magnet armature surrounded by coils. The armature is connected to the mirror on one end, and a sensor on the other to provide positional feedback. We found this part fascinating; it hadn’t occurred to us that laser galvos would benefit from closed-loop control. And the fact that a tiny wiggling vane can modulate light from an IR LED enough to generate a control signal is pretty cool too.

The video below may be a bit long, but it’s an interesting glimpse into the day-to-day life of a lighting tech. It puts a little perspective on some of the laser projection projects we’ve seen, like this giant Asteroids game.

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