New Motherboard Improves Old CRT Television

August 16, 2023 by Chris Lott 36 Comments

While browsing AliExpress from his digital basement, [Adrian Black] stumbled upon what seemed like a brand-new mainboard for a CRT television set. He decided to take a gamble and ordered one. It finally arrived, and was indeed a brand new product from 2023.

DIGITAL MAIN BOARD OF TV, Work ath [sic] HONGXUN products with the care and precision of a sculptor in each step, wonderful have no limits

Dubious marketing descriptions like “High Definition Digital Color TV Driver Board” aside, this turned out to be a fairly well-designed analog TV board. [Adrian] pulls a 20-year-old Magnavox ( Philips ) color television set from storage and begins the transplant operation. One interesting observation is the Magnavox board has almost the same layout as the new board, except for the orientation of the sections. The new CRT neck board had a different connector than the Magnavox set, but was designed to accept multiple sized sockets. [Adrian] just removed the new socket and replaced it with one from the old set. The mechanical issues were a bit more complicated, but nothing that a Dremel tool and a bit of hot glue can’t fix. The 220 VAC power supply was eventually modified to accept 110 VAC, which also enabled him to reconnect the degaussing coil.

[Adrian] has collected some relevant documentation in this GitHub repository, including schematics. Why bother with this at all? Well, until now, he didn’t have any way to test / view PAL RF signals in his lab. He was gambling on the new mainboard having a PAL tuner. It does, but as an unadvertised bonus, it supports NTSC and SECAM as well — but still not “HD digital color TV”, as far as we know. If you want a multi-standard TV in your lab, this solution may be worth considering. It appears there is still a market somewhere for new CRT televisions. If you have any background on this, please let us know down below in the comments.

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Repairing A Home Injection Molding Machine

August 5, 2023 by Maya Posch 10 Comments

When [Michael] over at the Teaching Tech YouTube channel bought a hobby injection molding machine a long time ago, one of the plans he had with it was to use it for grinding up waste bits of PLA filament for injection molding. Since the machine was bought from a US shop and [Michael] is based in Australia it required some modifications to adapt it to the local 220+ VAC mains, followed by adding a PID temperature controller and a small compressor to provide the compressed air rather than from a large shop compressor.

Although [Michael] had discussed using the machine for PLA with the seller to confirm that this would work, a user error meant that the now defective unit had been sitting idly for many years, until recently.

Since the machine had been gathering dust and rust in the garage, fixing the machine up took a complete teardown to remove corrosion and resolve other issues. After this the original fault was identified, which turned out to be a shorted wire near the heater which had been turned up to a too high temperature, leading to the release of magic smoke and banishment of the machine to the Pit of Despair, AKA the shadowy depths of one’s garage.

In this first installment, [Michael] cleaned up the machine and restored it to a working state. In the next part injection molding will be attempted again, which should give some idea of the feasibility of turning scraps of PLA and failed 3D prints into smooth injection molded parts, assuming you have the CNC machine or patience to carve out the requisite molds, of course.

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Let’s Listen To A Tape — Paper Tape

August 3, 2023 by Al Williams 9 Comments

These days, data is as likely as not to be “in the cloud.” Otherwise, it’s probably on a USB flash drive or SD card. But in the old days, paper tape was a widespread way to store and retrieve data. A common way to start the day at the office was to toggle in a few dozen bytes of bootloader code, thread a bigger bootloader tape into your TeleType paper tape reader, and then get your coffee while the more capable bootloader clunked its way into memory. Then you could finish your brew while loading the tape with your compiler or whatever you wanted. [Scott Baker] has a Heathkit H8 and decided using a paper tape machine with it and some of his other gear would be fun.

Instead of a TeleType, [Scott] picked up a used paper tape machine from FANUC intended for the CNC industry. They are widely available on the surplus market, although a working machine might run you $500. [Scott] paid $200, so he had some work to do to make the unit operational.

Paper tape had a few varieties. For computer work, you usually had a tape that could hold eight holes across, one for each bit in a byte. However, there are also 6-bit and 5-bit tapes for special purposes or different encodings (old TeleTypes used 5-bit characters in Baudot). The paper choice varied too. You could get plain paper, oiled paper, which maybe didn’t jam as often, and Mylar, which is less likely to shred up when it does jam.

To make things even more difficult, the machines all worked a little differently as well. Sure, punches almost all use solenoids. But the tape transport was sometimes a pinch roller and sometimes a sprocket-style drive. Reading the holes could be done with mechanical contacts or optically. Some punches left little “hanging chads” on the tape, so you didn’t have to empty a confetti box to throw away the chad.

The repair job was interesting. Inside the machine is an 8051 microcontroller. There was no clock, and the circuit used two custom modules. One was simply a crystal, and the other was an oscillator. Removing both allowed a modern can oscillator to replace both modules. The next problem was a fried serial output driver. Replacing that got things working except for random resets due to a faulty brown-out reset circuit. That was easy to fix, too.

Of course, if you are really cheap, it is easy to make a paper tape reader from 8 phototransistors, and pulling tape through by hand isn’t unheard of. It can even talk USB. We’ve even seen a conference badge that can read tapes.

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Microsoft Now Offering Parts And Repair Guides For Xbox Controllers

August 2, 2023 by Tom Nardi 11 Comments

We’re big fans of repairable hardware here at Hackaday, so much so that when we see a company embracing the idea that their products should actually be serviced rather than thrown in the trash, we like to call attention to it. Yes, that even includes when it’s Microsoft.

This community has had a mixed relationship with the Redmond software giant, to say the least. But we’ve still got to give them credit when they do something positive. Not only are they offering a full selection of replacement parts for both the standard and Elite Xbox controllers, they’ve also provided written instructions and step-by-step video guides on how to install your new parts.

For those of you who stopped playing console games when the controllers still only had two buttons, this might not seem like such a big deal. But considering a new Xbox Elite Wireless Controller will set you back a dizzying $180, it’s not hard to see why some folks would be excited about the possibility of swapping out the guts of the thing for $50.

Of course, these parts were already available from third party sellers, and iFixit naturally has repair guides for all the different flavors of Xbox controllers. Nothing about what Microsoft is doing here makes the Xbox controller fundamentally any easier to repair than it was previously. But the fact that the company isn’t treating their customers like adversaries is a step in the right direction.

Valve has been similarly open about the internals of the Steam Deck, though their presentation was a bit dramatic, and even Sony provided an official teardown video for the PS5. We’re not sure why these companies are willing to pull back the curtain when it comes to gaming hardware. Whatever the reason, we’re certainly not complaining.

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An exploded view of an AirPods Pro case. The outer case consists of two long, capsule-shaped sections that enclose several smaller parts including the wireless charging cable, contacts for charging the AirPods themselves, and the top rounded protective piece for the buds that nestles into the top capsule. This version includes screws to fasten everything together instead of adhesives.

Fixing Some More Of Apple’s Design Mistakes

August 2, 2023 by Navarre Bartz 26 Comments

Love them or hate them, there’s no denying that Apple has strayed from the Woz’s original open platform ideal for the Apple II. [Ken Pillonel] is back for another round of fixing Apple’s repairability mistakes with a full complement of 3D printable replacement parts for the AirPods Pro case.

While modeling all of the parts would be handy enough for repairing a device with a 0/10 iFixit score, [Pillonel] modified the parts to go together with screws instead of adhesive so any future repairs don’t require cracking the plastic egg. He says, “By showcasing the potential for repairability, I hope to inspire both consumers and multi-billion dollar companies, like Apple, to embrace sustainable practices in their products.”

[Pillonel]’s repairability exploits may seem familiar to readers from his previous work on adding USB-C to the iPhone and the AirPods Pro case. If you just need to retrieve a lost AirPod, you might try an electromagnet, or you can make a Bluetooth receiver from a pair of knock-off buds.

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All American Five Lives Again

August 1, 2023 by Al Williams 18 Comments

If you haven’t heard of an “all-American five,” then you probably don’t dig through bins for old radios. The AA5 is a common design for old AM radios that use five tubes: a rectifier, an oscillator/mixer, an IF amplifier, a detector, and a single tube for driving the speaker. [Mikrowave1] took an old specimen of such a radio from the mid-1950s and wanted to restore it. You can see how it went in the video below.

One feature of the design is that the set had a “hot chassis,” which means you really want to use an isolation transformer before you work on it. We were taught to touch a chassis with the back of our hand first because of radios like this. If it is “hot,” the muscle contraction would throw your arm away from the radio instead of forcing you to grip it uncontrollably.

The GE radio had many quality design touches you don’t always see in a radio like this. The mix of brands indicates that the radio has had tubes replaced in the past. It also had a clearly replaced electrolytic capacitor. Surprisingly, all the tubes were good, although the power output tube was marginal. However, a light bulb was bad and required a little surgery to allow for a slightly different replacement.

Some capacitors were neatly replaced, also. A lot of cleaning and testing later — along with a dropped tool — the radio was ready to play again. Fixing radios from this era is a great hobby. You can get to everything and you don’t really need anything fancy, although a tube tester is helpful. The classic method of troubleshooting is to either find audio on the volume control or not and then work your way backward or forward using a signal tracer or — since they are so readily available now — a scope. Alternatively, you could inject a signal at the volume control and work your way through the circuit until you can or can’t hear the injected signal.

Not the first tube radio we’ve watched being restored, of course. Need a tube tester?

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Examining Test Gear From Behind The Iron Curtain

August 1, 2023 by Al Williams 8 Comments

Back in 1978, an oscilloscope was an exotic piece of gear for most homebrewers. We expect they were even more rare in private hands behind the iron curtain, and [Thomas Scherrer] shows us a Soviet X1-7B combination oscilloscope and spectrum analyzer (he thinks, at least, it is a spectrum analyzer) that he got working.

The Soviet scope is clearly different with its Cyrillic front panel. Luckily, Google Translate was up to the task of decoding a picture of the device. However, the differences aren’t just cosmetic. The scope also has a very interesting rotating bezel around the round CRT. You can see a video of the 8.2 kg scope below.

A quick look inside looks pretty conventional for a scope of that era that used all transistors in the circuitry. The rotating bezel, though, also controls something that looks like a big mechanical switch and cavity or, perhaps, a big mechanical variable component of some kind.

Satisfied that the insides were in reasonable shape, [Thomas] was ready to try turning it on. We want to say it went well, but… there was censored audio, along with a loud noise, right after it was plugged in. Troubleshooting centered on what was producing a burned smell, but a quick examination didn’t turn up anything obvious, despite being localized to the power circuitry. The fuse didn’t blow, oddly, and — even more puzzling — the unit was off when plugged in!

It turns out the input power filter leaked to the chassis. Since he had a ground on the chassis, that explained the failure, and while it was annoying, it was better than getting a shock with a hot chassis. The second plug in went better.

It finally did work, at least somewhat, although he never explored some of the odd features the scope appears to have. We love the old boat anchor scopes but don’t see many Soviet instruments, at least not those of us on this side of the Atlantic.

We do see a few Soviet-era computers now and again. As for the fuse not blowing, it was shorted before the fuse, but apparently, fuses don’t always blow when you expect them to, anyway.

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