Restoring A Dead Commodore 128DCR

Another day, another retro computer lovingly restored to like-new condition by [Drygol]. This time, the subject of his attention is a Commodore 128DCR that earned every bit of the “For Parts, Not Working” condition it was listed under. From a spider infestation to a cracked power supply PCB, this computer was in quite a state. But in the end he got the three decade old machine back in working condition and even managed to teach it a few new tricks along the way.

Obviously the shattered PSU was the most pressing issue with the Commodore. Interestingly, the machine still had its warranty seal in place on the back, so whatever happened to this PSU seems to have occurred without human intervention.

Rather than just replacing the PSU, [Drygol] first pieced the board back together with the help of cyanoacrylate glue, and then coated the top with an epoxy resin to give it some mechanical strength. On the back side the traces were either repaired or replaced entirely with jumper wires where the damage was too severe.

With the PSU repaired and tested, he moved on to cleaning the computer’s main board and whitening all the plastic external components. Even the individual keycaps took a bath to get them looking like new again. This put the computer in about as close to like-new condition as it could get.

But why stop there? He next installed the JiffyDOS modification to improve system performance, and wired in an adapter that lets the computer output a crisp 80 columns over S-Video. It’s safe to say this particular Commodore is in better shape now than it was when it rolled off the assembly line.

While an impressive enough final result, this is still fairly tame for [Drygol]. If you want to see a real challenge, take a look at the insane amount of work that went into recreating this smashed Atari 800XL case.

Considering The Originality Question

Many Hackaday readers have an interest in older technologies, and from antique motorcycles to tube radios to retrocomputers, you own, conserve and restore them. Sometimes you do so using new parts because the originals are either unavailable or downright awful, but as you do so are you really restoring the item or creating a composite fake without the soul of the original? It’s a question the railway film and documentary maker [Chris Eden-Green] considers with respect to steam locomotives, and as a topic for debate we think it has an interest to a much wider community concerned with older tech.

Along the way the film serves as a fascinating insight for the non railway cognoscenti into the overhaul schedule for a working steam locomotive, for which the mainline railways had huge workshops but which presents a much more significant challenge to a small preserved railway. We wrote a year or two ago about the world’s first preserved railway, the Welsh Tal-y-Llyn narrow gauge line, and as an example the surprise in the video below is just how little original metal was left in its two earliest locomotives after their rebuilding in the 1950s.

The film should provoke some thought and debate among rail enthusiasts, and no doubt among Hackaday readers too. We’re inclined to agree with his conclusion that the machines were made to run rather than gather dust in a museum, and there is no harm in a majorly-restored or even replica locomotive. After all, just as a retrocomputer is as much distinguished by the software it runs, riding a steam train is far more a case of sights and smells than it is of knowing exactly which metal makes up the locomotive.

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Restoring A Rusty Rebar Cutter

We’ve all probably come across hunks of junk that used to be tools, long-neglected and chemically welded into a useless mass of solid rust. Such items are available for a pittance at the local flea market, or more likely found in an old barn or rotting on a junk pile. They appear to be far beyond salvage, but with the proper application of elbow grease and penetrating lubricants, even a nasty old seized-up rebar cutter can live again.

We honestly almost passed up on the video below when it came across our feed. After all, a rebar cutter is a dead-simple device, and half the fun of restoration videos like those made by [my mechanics] is seeing all the parts removed, restored, and replaced. But it ended up being far more interesting than we expected, and far more challenging too.

The cutter was missing its original handle and looked for all the world like it had been cast from a solid piece of iron oxide. [my mechanics] was able to get the main pivot bolts free with a combination of leverage, liberal application of penetrating oil, drilling, and the gentle persuasion of a hydraulic press.

These efforts proved destructive to both bolts, so new ones were made on the lathe, as were a number of other parts beyond saving. New cutters were fabricated from tool steel and a new handle was built; before anyone comments on anyone’s welding skills, please read [Jenny]’s recent article on the subject.

The finished product is strikingly dissimilar to the starting lump of oxidized junk, so there’s going to to be some debate in calling this a “restoration” in the classical sense. The end result of a [my mechanics] video is invariably a tool or piece of gear that looks far better than it did the day it was made, and any one of them would get a place of honor on our shelf. That said, he’d probably be swiftly shown the door if he worked at the Smithsonian.

Whatever you want to call these sort of videos, there are tons of them out there. We’ve featured a few examples of the genre, from the loving rehabilitation of classic Matchbox cars to rebuilding an antique saw set. They’re enough to make us start trolling garage sales. Or scrap yards.

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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 LensRentals.com 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 Hackaday.io, 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.