Apple Newton Gets Rebuilt Battery Pack

December 13, 2024 by Bryan Cockfield 14 Comments

We all carry touch screen computers around in our pockets these days, but before the smartphone revolution, there was the personal digital assistant (PDA). While it wasn’t a commercial success, one of the first devices in this category was the Apple Newton. Today they’re sought after by collectors, although most of the ones surviving to this day need a bit of rework to the battery pack. Luckily, as [Robert’s Retro] shows, it’s possible to rebuild the pack with modern cells.

By modern standards, the most surprising thing about these battery packs is both that they’re removable and that they’re a standard size, matching that of AA batteries. The Newton battery pack uses four cells, so replacing them with modern rechargeable AA batteries should be pretty straightforward, provided they can be accessed. This isn’t as easy, though. In true Apple fashion the case is glued shut, and prying it apart can damage it badly enough so it won’t fit back in the tablet after repair is complete. The current solution is to cut a hatch into the top instead and then slowly work on replacing the cells while being careful to preserve the electronics inside.

[Robert’s Retro] also demonstrates how to spot weld these new AA batteries together to prepare them for their new home in the Newton case. With the two rows fastened together with nickel strips they can be quickly attached to the existing electrical leads in the battery pack, and from there it’s just a matter of snapping the batteries into the case and sliding it back into the tablet. If you’re looking for something a bit more modern, though, we’d recommend this Apple tablet-laptop combo, but it’s not particularly easy on the wallet.

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Saving An Electron Microscope From The Trash

December 13, 2024 by Maya Posch 17 Comments

Who wouldn’t want to have a scanning electron microscope (SEM)? If you’re the person behind the ProjectsInFlight channel on YouTube, you certainly do. In a recent video it’s explained how he got his mittens on a late 1980s, early 1990s era JEOL JSM-5200 SEM that was going to be scrapped. This absolute unit of a system comes with everything that’s needed to do the imaging, processing and displaying on the small CRT. The only problem with it was that it was defective, deemed irreparable and hence the reason why it was headed to the scrap. Could it still be revived against all odds?

The JEOL JSM-5200 SEM after being revived and happily scanning away. (Credit: ProjectsInFlight, YouTube)

The good news was that the unit came with the manual and schematics, and it turns out there’s an online SEM community of enthusiasts who are more than happy to help each other out. One of these even had his own JSM-5200 which helped with comparing the two units when something wasn’t working. Being an SEM, the sample has to be placed in a high vacuum, which takes a diffusion vacuum pump, which itself requires a second vacuum pump, all of which requires voltages and electronics before even getting to the amplification circuitry.

Since the first problem was that this salvaged unit wasn’t turning on, it started with the power supply and a blown fuse. This led to a shorted transformer, bad DC-DC converters, a broken vacuum pump, expired rubber hoses and seals, and so on, much of which can be attributed simply to the age of the machine. Finding direct replacements was often simply impossible to very expensive, necessitating creative solutions along with significant TLC.

Although there are still some small issues with for example the CRT due to possibly bad capacitors, overall the SEM seems to be in working condition now, which is amazing for a unit that was going to be trashed.

Thanks to [Hans] for the tip.

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The £25,000 Tom Evans Pre-Amp Repair And A Copyright Strike

December 7, 2024 by Maya Posch 101 Comments

We were recently notified by a reader that [Tom Evans] had filed a copyright claim against [Mark]’s repair video on his Mend it Mark YouTube channel, taking down said repair video as well as [Mark]’s delightful commentary. In a new video, [Mark] comments on this takedown and the implications. The biggest question is what exactly was copyrighted in the original video, which was tough because YouTube refused to pass on [Mark]’s questions or provide further details.

In this new video the entire repair is summarized once again using props instead of the actual pre-amp, which you can still catch a glimpse of in our earlier coverage of the repair. To summarize, there was one bad tantalum capacitor that caused issues for one channel, and the insides of this twenty-five thousand quid pre-amp looks like an artistic interpretation of a Jenga tower using PCBs. We hope that this new video does stay safe from further copyright strikes from an oddly vengeful manufacturer after said manufacturer event sent the defective unit to [Mark] for a repair challenge.

Since this purportedly ‘audiophile-level’ pre-amplifier uses no special circuits or filtering – just carefully matched opamps – this is one of those copyright strike cases that leave you scratching your head.

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How Corroded Can A Motherboard Be?

December 5, 2024 by Al Williams 9 Comments

We will admit it. If we found a 386 motherboard as badly corroded as the one [Bits und Bolts] did, we would trash it—not him, though. In fact, we were surprised when he showed it and said he had already removed most of it in vinegar. You can check the board out in the video below.

There was still a lot of work to do on both the front and back of the board. The motherboard was a Biostar and while it isn’t as dense as a modern board, it still had plenty of surface mount parts jammed in.

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Fluke Meter Fails With A Simple Problem

December 4, 2024 by Al Williams 19 Comments

[TheHWcave] found a Fluke 27 multimeter that looked like it had had quite a rough life. At first, the display flashed an overload indicator until he gave it a good smack—or, as he likes to call it, percussive maintenance. Even then, it would not give good readings, so it was time to open it up.

The display did work, so the obvious theory was something wrong with the analog board. Removing the shields showed what looked like a normal enough PCB. Or at least, the components looked fine. But on the solder side of the board, there was some corrosion on two contacts, so some careful cleaning and resoldering fixed the meter to be as good as new on at least some scales.

Tracing the pins, the corrosion put a resistor between two pins of an op-amp. The only remaining problem was the milliamp scale, but that was a simple blown fuse in the line. Since it was working, it was worth some time to clean up the ugly exterior, which is only cosmetic but still worth a little effort. He left the plastic case cracked and beaten, but he put a lot of effort into clearing up the display window.

You might wonder why you’d fix a meter when you can get one so cheap. However, these name-brand meters are high-quality and new, quite expensive. Even older ones can be worth the effort. While you usually don’t need an X-ray machine to fix something like this, it can’t hurt.

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Saving A Samsung TV From The Dreaded Boot Loop

November 30, 2024 by Lewin Day 39 Comments

[eigma] had a difficult problem. After pulling a TV out of the trash and bringing it home, it turned out it was suffering from a troubling boot loop issue that basically made it useless. As so many of us do, they decided to fix it…which ended up being a far bigger task than initially expected.

The TV in question was a Samsung UN40H5003AF. Powering it up would net a red standby light which would stay on for about eight seconds. Then it would flicker off, come back on, and repeat the cycle. So far, so bad. Investigation began with the usual—checking the power supplies and investigating the basics. No easy wins were found. A debug UART provided precious little information, and schematics proved hard to come by.

Eventually, though, investigation dialed in on a 4 MB SPI flash chip on the board. Dumping the chip revealed the firmware onboard was damaged and corrupt. Upon further tinkering, [eigma] figured that most of the dump looked valid. On a hunch, suspecting that maybe just a single bit was wrong, they came up with a crazy plan: use a script to brute-force flipping every single bit until the firmware’s CRC check came back valid. It took eighteen hours, but the script found a valid solution. Lo and behold, burning the fixed firmware to the TV brought it back to life.

It feels weird for a single bit flip to kill an entire TV, but this kind of failure isn’t unheard of. We’ve seen other dedicated hackers perform similar restorations previously. If you’re out there valiantly rescuing e-waste with these techniques, do tell us your story, won’t you?

Close Shave For An Old Oscilloscope Saved With A Sticky Note

November 23, 2024 by Dan Maloney 12 Comments

When you tear into an old piece of test equipment, you’re probably going to come up against some surprises. That’s especially true of high-precision gear like oscilloscopes from the time before ASICs and ADCs, which had to accomplish so much with discrete components and a lot of engineering ingenuity.

Unfortunately, though, those clever hacks that made everything work sometimes come back to bite you, as [Void Electronics] learned while bringing this classic Tektronix 466 scope back to life. A previous video revealed that the “Works fine, powers up” eBay listing for this scope wasn’t entirely accurate, as it was DOA. That ended up being a bad op-amp in the power supply, which was easily fixed. Once powered up, though, another, more insidious problem cropped up with the vertical attenuator, which failed with any setting divisible by two.

With this curious symptom in mind, [Void] got to work on the scope. Old analog Tek scopes like this use a bank of attenuator modules switched in and out of the signal path by a complex mechanical system of cams. It seemed like one of the modules, specifically the 4x attenuator, was the culprit. [Void] did the obvious first test and compared the module against the known good 4x module in the other channel of the dual-channel scope, but surprisingly, the module worked fine. That meant the problem had to be on the PCB that the module lives on. Close examination with the help of some magnification revealed the culprit — tin whiskers had formed, stretching out from a pad to chassis ground. The tiny metal threads were shorting the signal to ground whenever the 4x module was switched into the signal path. The solution? A quick flick with a sticky note to remove the whiskers!

This was a great fix and a fantastic lesson in looking past the obvious and being observant. It puts us in the mood for breaking out our old Tek scope and seeing what wonders — and challenges — it holds.

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