repair

142 Articles

Neopixels Recreate Pinball Color Wheel That Never Was

July 25, 2019 by 6 Comments

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.

Liquid Damaged MacBook Saved With A Keen Eye

July 9, 2019 by 18 Comments

Even among those of us with a penchant for repairing electronics, there are some failures which are generally considered too severe to come back from. A good example is liquid damage in a laptop; with so many components and complex circuits crammed into such a small area, making heads or tails of it once the corrosion sets in can be a real nightmare. Especially in the case of an older laptop, the conventional wisdom is to try and recover your files and then buy a new one.

But as we’ve come to learn, [Jason Gin] is not a man who often finds himself concerned with conventional wisdom. After finding an older MacBook with suspected liquid damage, he decided to see what it would take to restore it to working order. According to a note on the device, the screen was dead, the USB ports were fried, the battery didn’t take a charge, and it wouldn’t boot. No problem then, should be easy.

Upon opening up the circa-2012 laptop, [Jason] found the machine to be riddled with corrosion. We’re not just talking surface gunk either. After giving everything a good cleaning with isopropyl alcohol, the true extent of the damage became clear. Not only had traces on the PCB rotted away, but there were many components that were either damaged or missing altogether. Whatever spilled inside this poor Mac was clearly some nasty stuff.

[Jason] used OpenBoardView to pull up schematics and diagrams of the motherboard, and started the arduous task of visually comparing them to his damaged unit. In some areas, the corrosion was so bad he still had trouble locating the correct traces and pads. But with time and effort, he was able to start probing around and seeing what components had actually given up the ghost.

For the USB ports it ended up being a bad 10-microfarad ceramic capacitor, but for the LCD, he ended up having to replace the entire backlight driver IC. The prospect of working on this tiny BGA-25 device might have been enough for some to throw in the towel, but compared to the hand-soldered magnet wire repairs required elsewhere on the board, [Jason] says the installation of the new LP8550 chip was one of the easier aspects of the whole operation.

The write-up is a great read if you like a good repair success story, and we especially like the way he documented his diagnosis and resulting work on a per-system basis. It makes it much easier to understand just how many individual fires [Jason] had to put out. But if you’re more interested in feats of steady-handed soldering, check out his recent project to add a PCI-E slot to the Atomic Pi.

Sprucing Up A Bell & Howell Model 34 Oscilloscope

July 4, 2019 by 17 Comments

We’ll admit it, in an era when you can get a four channel digital storage oscilloscope with protocol decoding for a few hundred bucks, it can be hard not to see the appeal of analog CRT scopes from decades past. Sure they’re heavy, harder to use, and less capable, but they just look so cool. Who could say no to having one of these classic pieces of gear on their bench?

[Cody Nybo] certainly couldn’t. Despite the fact that he already has a digital scope, he couldn’t pass up the chance to add a Bell & Howell Schools Model 34 from circa 1973 to his collection. It needed a bit of TLC before it could be brought back into service, but now it’s all fixed up and ready to put in some work. Not bad for a piece of gear with nearly a half-century on the clock.

The restoration of the Model 34 was aided by the fact that [Cody] got the original manual and schematics for the scope in the deal, which he was kind enough to scan and upload for the rest of the class to enjoy. Those of you who have worked on older electronics can already guess where the scope needed the most love: all the capacitors needed to be swapped out for fresh ones. He also found a few resistors that were out of spec, and the occasional bad solder joint here and there.

Even if you’re not looking to repair your own middle-aged oscilloscope, his pictures of the inside of Model 34 are fascinating. The scope was sold as a kit, so the construction is surprisingly simple and almost entirely point-to-point. Of course, there’s something of a trade-off at work: [Cody] says it won’t display much more than 2.5 MHz before things start getting wonky. But then again, that’s a more than reasonable frequency ceiling for audio work and most hobbyist projects.

Oscilloscopes have come a long way since the days when they had to draw out their readings on a piece of paper. While newer devices have all but buried the classic analog scope, a beauty like this would still have a place of honor in our lab.

Lighting Tech Dives Into The Guts Of Laser Galvanometers

June 29, 2019 by 11 Comments

There’s something magical about a laser light show. Watching that intense beam of light flit back and forth to make shapes and patterns, some of them even animated, is pretty neat. It leaves those of us with a technical bent wondering just exactly how the beam is manipulated that fast.

Wonder no more as [Zenodilodon], a working concert laser tech with a deep junk bin, dives into the innards of closed-loop galvanometers, which lie at the heart of laser light shows. Galvos are closely related to moving-coil analog meters, which use the magnetic field of a coil to deflect a needle against spring force to measure current. Laser galvos, on the other hand, are optimized to move a lightweight mirror back and forth, by tiny amounts but very rapidly, to achieve the deflection needed to trace out shapes.

As [Zeno] explains in his teardown of some galvos that have seen better days, this means using a very low-mass permanent magnet armature surrounded by coils. The armature is connected to the mirror on one end, and a sensor on the other to provide positional feedback. We found this part fascinating; it hadn’t occurred to us that laser galvos would benefit from closed-loop control. And the fact that a tiny wiggling vane can modulate light from an IR LED enough to generate a control signal is pretty cool too.

The video below may be a bit long, but it’s an interesting glimpse into the day-to-day life of a lighting tech. It puts a little perspective on some of the laser projection projects we’ve seen, like this giant Asteroids game.

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Repairdown: Disklavier DKC500RW Control Unit

June 3, 2019 by 54 Comments

If you’ve been kind enough to accompany me on these regular hardware explorations, you’ve likely recognized a trend with regards to the gadgets that go under the knife. Generally speaking, the devices I take apart for your viewing pleasure come to us from the clearance rack of a big box retailer, the thrift store, or the always generous “AS-IS” section on eBay. There’s something of a cost-benefit analysis performed each time I pick up a piece of gear for dissection, and it probably won’t surprise you to find that the least expensive doggy in the window is usually the one that secures its fifteen minutes of Internet fame.

DKC500RW installed on right side.

But this month I present to you, Good Reader, something a bit different. This time I’m not taking something apart just for the simple joy of seeing PCB laid bare. I’ve been given the task of repairing an expensive piece of antiquated oddball equipment because, quite frankly, nobody else wanted to do it. If we happen to find ourselves learning about its inner workings in the process, that’s just the cost of doing business with a Hackaday writer.

The situation as explained to me is that in the late 1990’s, my brother’s employer purchased a Yamaha Mark II XG “Baby Grand” piano for somewhere in the neighborhood of $20,000. This particular model was selected for its ability to play MIDI files from 3.5 inch floppy disks, complete with the rather ghostly effect of the keys moving by themselves. The idea was that you could set this piano up in your lobby with a floppy full of Barry Manilow’s greatest hits, and your establishment would instantly be dripping with automated class.

Unfortunately, about a month or so back, the piano’s Disklavier DKC500RW control unit stopped reading disks. The piano itself still worked, but now required a human to do the playing. Calls were made, but as you might expect, most repair centers politely declined around the time they heard the word “floppy” and anyone who stayed on the line quoted a price that simply wasn’t economical.

Before they resorted to hiring a pianist, perhaps a rare example of a human taking a robot’s job, my brother asked if he could remove the control unit and see if I could make any sense of it. So with that, let’s dig into this vintage piece of musical equipment and see what a five figure price tag got you at the turn of the millennium.

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Reproducing Vintage Plastic Parts In Top-Notch Quality

April 8, 2019 by 16 Comments

Plastic is a highly useful material, but one that can also be a pain as it ages. Owners of vintage equipment the world over are suffering, as knobs break off, bezels get cracked and parts warp, discolor and fail. Oftentimes, the strategy has been to rob good parts from other broken hardware and cross your fingers that the supply doesn’t dry up. [Eric Strebel] shows us that’s not the only solution – you can replicate vintage plastic parts yourself, with the right tools.

In the recording industry there’s simply no substitute for vintage gear, so a cottage industry has formed around keeping old hardware going. [Eric] was tasked with reproducing VU meter bezels for a classic Neve audio console, as replacement parts haven’t been produced since the 1970s.

The first step is to secure a good quality master for replication. An original bezel is removed, and polished up to remove scratches and blemishes from 40+ years of wear and tear. A silicone mold is then created in a plywood box. Lasercut parts are used to create the base, runner, and vents quickly and easily. The mold is then filled with resin to produce the final part. [Eric] demonstrates the whole process, using a clear silicone and dyed resin to make it more visible for the viewer.

Initial results were unfortunately poor, due to the silicone and hardener used. The parts were usable dimensionally, but had a hazy surface finish giving very poor optical qualities. This was rectified by returning to a known-good silicone compound, which was able to produce perfectly clear parts first time. Impressively, the only finishing required is to snap off the runner and vents. The part is then ready for installation. As a final piece of showmanship, [Eric] then ships the parts in a custom laser-engraved cardboard case. As they say, presentation is everything.

With modern equipment, reproducing vintage parts like knobs and emblems is easier than ever. Video after the break.

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Recover Data From Damaged Chips

January 30, 2019 by 6 Comments

Not every computer is a performance gaming rig. Some of us need cheap laptops and tablets for simple Internet browsing or word processing, and we don’t need to shell out thousands of dollars just for that. With a cheaper price tag comes cheaper hardware, though, such as the eMMC standard which allows flash memory to be used in a more cost-advantageous way than SSDs. For a look at some the finer points of eMMC chips, we’ll turn to [Jason]’s latest project.

[Jason] had a few damaged eMMC storage chips and wanted to try to repair them. The most common failure mode for his chips is “cratering” which is a type of damage to the solder that holds them to their PCBs. With so many pins in such a small area, and with small pins themselves, often traditional soldering methods won’t work. The method that [Jason] found which works the best is using 0.15 mm thick glass strips to aid in the reflow process and get the solder to stick back to the chip again.

Doing work like this can get frustrating due to the small sizes involved and the amount of heat needed to get the solder to behave properly. For example, upgrading the memory chip in an iPhone took an expert solderer numerous tries with practice hardware to finally get enough courage to attempt this soldering on his own phone. With enough practice, the right tools, and a steady hand, though, these types of projects are definitely within reach.