Repairing Crystal Earpieces

If you make crystal radios, you’ve probably got a few crystal earpieces. The name similarity is a bit coincidental. The crystal in a crystal radio was a rectifier (most often, these days, a germanium diode, which is, a type of crystal). The crystal in a crystal earpiece is a piezoelectric sound transducer.

Back in the 1960s, these were fairly common in cheap transistor radios and hearing aids. Their sound fidelity isn’t very good, but they are very sensitive and have a fairly high impedance, and that’s why they are good for crystal radios.

[Steve1001] had a few of these inexpensive earpieces that either didn’t work or had low sound output. He found the root cause was usually a simple problem and shares how to fix them without much trouble.

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Bringing The Best Laptop Ever Made Back To Life

Eight or nine years ago, Apple was on top of the world. The iPhone just revolutionized phones, Apple was still making computers, and these computers were actually repairable. Of the late 2008/early 2009 MacBook Pro, iFixit said, “What an incredible machine. We are very impressed by the ease with which the new MacBook Pro came apart. This machine should be a joy to work on”. Apple has come a long way since then.

macbook-reflow-shield[DocDawning] has a bit of a Mac hoarding problem, and frequently pays $20 for broken laptops of this vintage. Most of the time, the fix is simple: the RAM needs to be reseated, or something like that. Rarely, he comes across a machine that isn’t fixed so easily. The solution, in this case, is a deep dive into heat guns and thermal management. How do you bring a laptop back from the dead? [Dawning] shows you how.

Like the old XBox towel hack, the first thing to look for in dead electronics is broken solder balls. Of course, actually looking at broken solder balls is pretty hard, so you might as well just get out a heat gun and go at it. That’s exactly what [Dawning] did. With the clever application of an aluminum takeout tray to direct the heat flow, he blasted each of these chips with enough heat to hopefully melt all the balls.

With that, a working MacBook Pro was just a liberal application of thermal paste away. From $20 at the scrap heap to a working computer, [Dawning] did it. He successfully resuscitated a broken computer.

$2700 eBay Bet Pays off for this 14 GHz Spectrum Analyzer Repair

The eBay addiction starts small. One night you’re buying $3 buck-boost converters and cheap Chinese USB power packs. The next thing you know you’re spending thousands on dead instruments with no documentation. You’ve got the skills though, and if your bet that you can diagnose and repair a 14 GHz real-time spectrum analyzer is right, you’ll be putting a snazzy instrument on the bench for a fraction of the original $50,000 it cost.

Make some popcorn and get cozy before settling in to watch [Shahriar]’s video below, because it clocks in at just over an hour. But it’s pretty entertaining, and just seeing how Tektronix built the RSA 6114A spectrum analyzer is worth the time. Things are different when you’re piping microwave signals around the chassis of a beast such a this, the interior of which is densely packed with pluggable modules. Tek factory service would no doubt perform a simple module swap to get this machine running again, but [Shahriar] wasn’t having any of that on his $2,700 eBay find. After isolating the problem to the local-oscillator generator module, [Shahriar] takes us on a tour of where the signals go and what they do. We won’t reveal the eventual culprit, but suffice it to say that after a little SMD rework, [Shahriar] has a very fancy new instrument for the shop.

If this repair gives you the itch to get working on microwave circuits, maybe it’s time to build that backyard synthetic aperture radar set you’ve always wanted.

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Steve Collins: When Things Go Wrong In Space

[Steve Collins] is a regular around Hackaday. He’s brought homebrew LIDARs to our regular meetups, he’s given a talk on a lifetime’s worth of hacking, and he is the owner of the most immaculate Hackaday t-shirt we’ve ever seen.

For the 2016 Hackaday SuperConference,  [Steve] took a break from his day job of driving spacecraft around the Solar System. As you can imagine, NASA plans on things going wrong. How do you plan for that? [Steve] answers all your questions by telling you what happens when things go wrong in space.

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Repairing Flex Circuits By Accident

A while ago, [drygol] was asked to repair a few old Amiga keyboards. The key switches worked fine, but in the past decade or two, the flexible PCB ribbon connector has been mistreated, and was in an unworkable, nonfunctional state. The fragile traces underneath the green epoxy coating were giving way, but [drygol] found a few cool ways to repair these flex cables.

The end of this keyboard cable was beyond repair, but the Commodore engineers were gracious enough to leave a bit of slack in this keyboard connector. After cutting off the most damaged section, [drygol] had a strip of plastic, a few copper traces, and a green coating that had to be removed. The first attempt to remove this green covering used methanol, but that didn’t work. The next chemical attempt was with an epoxy solvent that contained nasty chemicals. This was applied to the end of the flex cable, with the remainder of the cable masked off by Kapton. It worked remarkably well.

In removing the Kapton masking tape, [drygol] discovered this green film sticks better to Kapton than it does to copper and plastic. A mechanical solution was found, allowing these keyboard cables to be easily repaired.

Of course, this was only half of the problems with these flexible circuits. Over the years, a few cracks appeared in the traces. To repair these broken traces, [drygol] turned to silver glue and a few laminations of Kapton to make this keyboard cable whole again. It worked, and the ancient keyboard was returned to service. Great work, and a fantastic observation for anyone with one of these keyboards sitting around: just grab a roll of Kapton to repair these circuits. It can’t get any easier than that.

Replacing a Failed Ebook Reader Battery

Resurrecting a beloved piece of tech can be a trying process when fighting through the mild heartbreak — doubly so if the product has been discontinued. When their old Sony PRS-T1 e-book reader refused to charge after leaving it on their dashboard during a hot day, [Andrea Gangemi] decided to leverage a little techno-necromancy and hack together a fix.

[Gangemi] found the problem to be a battery failure, but there was nary a replacement to be found. An old Motorola mobile phone battery ended up fitting the purpose nicely. Cracking open the e-book reader, de-soldering the old battery and — after deciphering which pins were which — installing the new one was simply done with a fine, high temperature soldering iron tip and Kapton tape to avoid short-circuiting. But hold on — the new battery wouldn’t charge, and the reader displayed a message saying that the battery was over heating; irony, thou art cruel.

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Home-made Adjustable Knife Jig

When sharpening a knife, it is critical to have the knife at the right angle. A knife jig handles this for you, letting you focus on getting the edge right. You could just buy one, but where’s the fun in that? [origamimavin] decided to make his own adjustable knife jig using bits he bought from the hardware store for $27, and which you might have in your junk pile. Fortunately for us, he’s written up the process in excellent detail, explaining the how and why of each step.

He used a couple of tools that you might not have lying around (a bandsaw and a belt sander), but these could be easily replaced with their manual cousins, or your local hackerspace will doubtless provide you access to them. Either way, it’s a simple build which could help your knives keep their clean, sharp edge for years to come.