A Vintage Monitor Lives Again With A New Heart

January 29, 2024 by Jenny List 25 Comments

Aside from keeping decades-old consumer-grade computing hardware working, a major problem for many retrocomputing enthusiasts lies in doing the same for vintage monitors. Whether your screen is a domestic TV or a dedicated monitor, the heat and voltage stress of driving a CRT made these devices significantly less reliable than many of their modern-day counterparts. [Adrian’s Digital Basement] has a worn-out and broken Commodore 1701 monitor, which he’s brought back to life with a modern circuit board and a CRT transplant.

Following on from a previous project, he’s using a replacement board sold as a repair option for CRT TVs on AliExpress. The Commodore monitor has its board on a metal chassis which takes the replacement with a bit of modification. He doesn’t say where the new CRT came from, but we’re guessing it was a late model TV as CRTs made over the last few decades are more interchangeable than might be expected. There’s a moment of mild dodginess as he makes a voltage doubler to run the 220 V board from 120 V with a pair of large electrolytic capacitors hot glued in place, but otherwise it’s a success.

At the end of it all after some testing and set-up he has a Commodore monitor with a new heart and multi-standard support. Is it really a Commodore monitor though, or should it have been repaired? It’s a difficult one to answer, but we’d suggest that CRT monitor repair is less easy today than it used to be because many of the parts are now difficult to find. If it saves at least some of the original from the dumpster it’s better than doing nothing. We wonder how long these upgrades will remain possible as even with Chinese plants making these boards and a handful of CRT TVs still appearing on AliBaba it’s clear that CRTs are at the very end of their life.

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X-Ray CT Scanners From EBay, Brought Back To Life

January 22, 2024 by Donald Papp 13 Comments

If you have ever wondered what goes into repairing and refurbishing an X-ray Computed Tomography (CT) scanner, then don’t miss [Ahron Wayne]’s comprehensive project page on doing exactly that. He has two small GE Explore Locus SP machines, and it’s a fantastic look into just what goes into these machines.

CT scan of papyrus roll in a bamboo sheath.

These devices use a combination of X-rays and computer software to reconstruct an internal view of an object. To bring these machines back into service means not only getting the hardware to work correctly, but the software end (including calibration and error correcting) is just as important.

That means a lot of research, testing, and making do. For example, instead of an expensive calibration grid made from an array of tiny tungsten carbide beads, [Ahron] made do with a PCB laden with a grid of copper pads. The fab house might have scratched their heads a little on that one, but it worked just fine for his purposes and price was certainly right.

Tools like these enable all kinds of weird and wonderful projects of their own. So what can one do with such a machine? CT scanning can spot fake AirPods or enable deeper reverse engineering than a regular workshop is normally able to do.

What else? Shown here is an old foil Pokémon card ~~from an unopened package!~~ (Update: the scan is not from a card in a sealed package, it is just a scanned foil card. Thanks to Ahron for clarifying.) [Ahron] coyly denies having a pet project of building a large enough dataset to try to identify cards without opening the packs. (Incidentally, if you just happen to have experience with supervised convolutional neural networks for pix2pix, he asks that you please reach out to him.)

The real power of CT scanning becomes more apparent if you take a look at the videos embedded below the page break. One is a scan of an acorn, [Ahron]’s first successful scan. Another is an interesting scan of a papyrus roll in a bamboo sheath. Both of the videos are embedded below.

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In Praise Of Old Meters

January 12, 2024 by Al Williams 54 Comments

We are spoiled with multimeters today. Even the cheapest meter you will get these days is almost surely digital with a tremendous input impedance. But a few decades ago, meters were almost always analog affairs. To make a precise measurement, you needed a mirror under the meter to ensure you read the needle correctly. Moreover, a common meter wouldn’t have that high of an input impedance. If you spent more, you could get a VTVM and, later, one that used FETs to provide high input impedance. [Peter AA2VG] just picked up a vintage Micronta FET volt-ohm meter to join some of the other new and old meters in his shack. You can check it out in the video below.

[Peter] already has a Simpson and a more modern Fluke meter. The Simpson, however, doesn’t have a tube or FET amplifier. The Fluke is nice, but there is something about the needle on an analog meter. If you aren’t old enough to remember, the Micronta brand was a Radio Shack label.

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Saving An Expensive Sony HW65ES Projector With Some Fresh Chips

January 2, 2024 by Maya Posch 11 Comments

When you’re the proud owner of a beast of a projector like the Sony HW65ES (£2800 in 2016), you are understandably upset when it stops working. In the case of [Wettergren] it appears that a lightning strike in the Summer of 2021 managed to take out the HDMI inputs, with no analog or other input options remaining. Although a new board with the HDMI section would cost 500 €, it couldn’t be purchased separately, and a repair shop quoted 1800 € to repair it, which would be a raw deal. So, left with the e-waste or DIY repair options, [Wettergren] chose the latter.

Suffice it to say that taking one of these large projectors apart is rather an adventure, as is extracting the input PCB. On this board some probing showed that while the HDMI 2 port showed some signs of life, with its DDC lines functioning and the EDID readable. The HDMI 1 port had a dead short on these lines, which got traced back to a dead Sil9589CTUC IC, while HDMI was connected to the Sil9679 IC next to it. With this easy part done, the trick was finding replacements for what is decidedly not an off-the-shelf component, but fortunately EBay came through. This just left the slow agony of microsoldering to replace the dead IC, which ultimately succeeded.

After the second repair attempt in May of 2022, the projector is still working in December of 2023, proving that a bit of persistence, a bit of EBay luck and a microsoldering bench with the skills to use it can bring many devices back from the brink to give them a happy second life.

The scope, with new knobs and stickers on it, front panel renovated

Explosion-Scarred Scope Gets Plastic Surgery Hackerspace Style

January 2, 2024 by Arya Voronova 9 Comments

Some equipment comes with a backstory so impressive, you can’t help but treat it with reverence. For instance, this Hantek scope’s front panel and knobs have melted when a battery pack went up in flames right next to it. Then, it got donated to the CADR hackerspace, who have in turn given us a scope front panel refurbishing master class (translated, original), demonstrating just how well a typical hackerspace is prepared for performing plastic surgery like this.

All of the tools they used are commonplace hackerspace stuff, and if you ever wanted to learn about a workflow for repairs like these, their wiki post is a model example, described from start to end. They show how they could use a lasercutter to iterate through figuring out mechanical dimensions of the labels, cutting the silhouette out of cardboard as they tweaked the offsets. Then, they designed and printed out the new front panel stickers, putting them through a generic laminator to make them last. An FDM printer helped with encoder and button knob test fits, with the final version knobs made using a resin printer.

Everything is open-source – FreeCAD knob designs, SVG stickers, and their CorelDraw sources are linked in the post. With the open-source nature, there’s plenty of room to improvement – for instance, you can easily put these SVGs through KiCad and then adorn your scope with panels made out of PCBs! With this visual overhaul, the Hantek DSO5102P in question has gained a whole lot more character. It’s a comprehensive build, and it’s just one of the many ways you can compensate for a damaged or missing shell – check out our comprehensive DIY shell guide to learn more, and when you get to designing the front panel, we’ve highlighted a few lessons on that too.

Repairing An HP Power Supply

December 15, 2023 by Al Williams 3 Comments

One of the interesting things about living in modern times is that a confluence of the Internet and rapid changes in the electronics industry means that test gear that used to be astronomically priced is now super affordable. Especially if, like [Frankie Mashockie], you can do a little repair work. He picked up an HP6038A power supply for $50. We couldn’t find the original list price, but even refurbs from “professional” sources go for around $800. However, the $50 price came with a “for parts” disclaimer.

The power supply is autoranging. You usually think of that as a feature of meters. In a power supply, autoranging means the device can adjust the voltage based on load as you can see explained in the video below.

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Hacker Tactic: Internal ESD Diode Probing

December 14, 2023 by Arya Voronova 15 Comments

Humans are walking high voltage generators, due to all the friction with our surroundings, wide variety of synthetic clothes, and the overall ever-present static charges. Our electronics are sensitive to electrostatic discharge (ESD), and often they’re sensitive in a way most infuriating – causing spurious errors and lockups. Is there a wacky error in your design that will repeat in the next batch, or did you just accidentally zap a GPIO? You wouldn’t know until you meticulously check the design, or maybe it’s possible for you to grab another board.

Thankfully, in modern-day Western climates and with modern tech, you are not likely to encounter ESD-caused problems, but they were way more prominent back in the day. For instance, older hackers will have stories of how FETs were more sensitive, and touching the gate pin mindlessly could kill the FET you’re working with. Now, we’ve fixed this problem, in large part because we have added ESD-protective diodes inside the active components most affected.

These diodes don’t just help against ESD – they’re a general safety measure for protecting IC and transistor pins, and they also might help avoid damaging IC pins if you mix. They also might lead to funny and unexpected results, like parts of your circuit powering when you don’t expect them to! However, there’s an awesome thing that not that many hackers know — they let you debug and repair your circuits in a way you might not have imagined.

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