Arduino Takes Control Of Dead Business Card Cutter

September 10, 2020 by Tom Nardi 13 Comments

It’s a common enough situation, that when an older piece of equipment dies, and nobody wants to spend the money to repair it. Why fix the old one, when the newer version with all the latest bells and whistles isn’t much more expensive? We all understand the decision from a business standpoint, but as hackers, it always feels a bit wrong.

Which is exactly why [tommycoolman] decided to rebuild the office’s recently deceased Duplo CC-330 heavy duty business card cutter. It sounds like nobody really knows what happened to the machine in the first place, but since the majority of the internals were cooked, some kind of power surge seems likely. Whatever the reason, almost none of the original electronics were reused. From the buttons on the front panel to the motor drivers, everything has been implemented from scratch.

An Arduino Mega 2560 clone is used to control four TB6600 stepper motor drivers, with a common OLED display module installed where the original display went. The keypad next to the screen has been replaced with 10 arcade-style buttons soldered to a scrap of perfboard, though in the end [tommycoolman] covers them with a very professional looking printed vinyl sheet. There’s also a 24 V power supply onboard, with the expected assortment of step up and step down converters necessary to feed the various electronics their intended voltages.

In the end, [tommycoolman] estimates it took about $200 and 30 hours of work to get the card cutter up and running again. The argument could be made that the value of his time needs to be factored into the repair bill as well, but even still, it sounds like a bargain to us; these machines have a four-figure price tag on them when new.

Stories like this one are important reminders of the all wondrous things you can find hiding in the trash. Any time a machine like this can be rescued from the junkyard, it’s an accomplishment worthy of praise in our book.

Spoofing An Analog Rotary Knob With An ATtiny, And Vampiric Power

July 14, 2020 by Donald Papp 22 Comments

[Mitxela]’s repair of a Roland JV-1080 (a rack-mounted 90s-era synthesizer) sounds simple: replace a broken rotary encoder on the front panel. It turned out to be anything but simple, since the part in question is not today’s idea of a standard rotary encoder at all. The JV-1080 uses some kind of rotary pulse switch, which has three outputs (one for each direction, and one for pushing the knob in like a button.) Turn the knob in one direction, and one of the output wires is briefly shorted to ground with every detent. Turn it the other way, and the same happens on the other output wire. This is the part that needed a replacement.

The finished unit uses a modern rotary encoder and microcontroller in place of the original part, and implements a few tricks to power it.

Rather than track down a source for the broken part, [Mitxela] opted to replace it with a modern rotary encoder combined with an ATtiny85 microcontroller to make it act like something the JV-1080 understands and expects. There was an additional wrinkle, however. The original rotary pulse switch is an entirely passive device, and lives at the end of a four-conductor cable with no power provided on it. How could the ATtiny85 be powered without resorting to running a wire to a DC voltage supply somewhere? Success was had, but it did take some finessing.

For the power, it turns out that the signal wires are weakly pulled up to +5 V and [Mitxela] used that for a power supply to the microcontroller. Still, by itself that wasn’t enough, because the ATtiny85 can easily consume more current than the weak pullups can source. We really recommend reading all the details in [Mitxela]’s writeup, but the short version is that the ATtiny85 does two things.

First, it minimizes its power usage by spending most of its time in sleep mode (consuming barely any power at all) and uses an interrupt to wake up just long enough to handle knob activity. Second, the trickle of power from the weak pullups doesn’t feed the ATtiny directly. It charges a 100 uF capacitor through a diode, and that is what keeps the microcontroller from browning out during its brief spurts of activity. Even better, after browsing the datasheet for the ATtiny, [Mitxela] saw it was possible to use the built-in ESD protection diodes for this purpose instead of adding a separate component.

It’s a neat trick and makes for a very compact package. Visit the project’s GitHub repository to dive into the nitty gritty. In the end, a single assembly at the end of a 4-wire connector acts just like the original passive component, no extra wires or hardware modifications needed.

When opening older hardware it’s never quite certain what will be found on the inside. But at least [Mitxela]’s repair duties on this synth didn’t end up with him tripping out on LSD.

Vintage Instrument Gets Modern Replacement For Unobtainium Parts

July 10, 2020 by Dan Maloney 13 Comments

One of the best parts about Hackaday is how much you learn from the projects that people tackle, especially when they are repairs on old gear with unknown failure modes and potentially multiple problems. By the same token, the worst part about Hackaday is seeing what other people are capable of and knowing that you’ve got a long way to go to catch up to them.

A case in point is [Curious Marc]’s recent repair of an old pulse generator. The instrument in question is an H-P 8082A, a device from a time when H-P was a place where “good engineers managed by even better engineers [wanted] to help other engineers,” as [Marc] so eloquently puts it. The instrument was capable of 250 MHz output with complete control over the amplitude, frequency, duty cycle, and rising and falling edge geometry of the pulses, in addition to being able to output double pulses. For an all-analog instrument made in 1974, it was in decent shape, and it still powered up and produced at least the square wave output. But [Marc]’s exploration revealed a few problems, which are detailed and partially addressed in the first video below.

In part two [Marc] goes after the problem behind the pulse delay function. He traced it to a bad IC, which was bad news since it was a custom H-P part using emitter-coupled logic (ECL) to achieve the needed performance that can no longer be sourced. So naturally, [Marc] decided to replace the chip with a custom circuit. The design and simulation of the circuit are detailed in part two, while the non-trivial details of designing a PCB to handle the high-speed signals take up most of part three. We found the details on getting the trace impedance just right fascinating.

In the end, [Marc]’s pulse generator was salvaged. It’ll go into service helping him probe the mysteries of vintage electronics from the Apollo era, so we’re looking forward to seeing more about this great old instrument.

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Commodore SX-64 Keyboard Upgraded From Trash To Treasure

June 30, 2020 by Kristina Panos 6 Comments

Released in 1984, the Commodore SX-64 Executive Computer was one of the first ~~portable~~ luggable color computers. It cost twice as much as a Commodore 64, had a tiny 5″ diagonal screen, and couldn’t actually support both 5¼” drives as advertised. On the upside, people say it had a slightly better keyboard than its classic cousin.

[Drygol] agreed to restore the keyboard from a friend’s Commodore SX-64 sight-unseen, and boy was this thing in bad shape. Most people would probably consider the condition a shame and write it off as a lost cause, since two of the corners were missing most of their plastic. But [Drygol] isn’t most people. [Drygol] had mad restoration skills to begin with, and this project honed them to a razor’s edge.

Plenty of the other vintage computer restorations [Drygol] has done required plastic welding, which uses heat or a lot of friction to smooth over cracks. Some of those have not stood the test of time, so he’s now in the habit of stabilizing cracks with brass mesh before filling them with fiberglass putty.

The best part is how [Drygol] managed to rebuild the corners using the same methods, soldering the brass mesh at the 90° joins, and reinforcing them with thick copper wire before beginning the painstaking putty/sand/putty process. The use of blank copper clad boards as straight edges and thickness gauges is genius.

There’s a whole lot to learn here, and the adventure beings with something that probably keeps a lot of people from trying stuff like this in the first place: how do you safely remove the badges?

You’re right, plastic welding is awesome. There even used to be a toy plastic welder. But there’s no need to troll the electronic auction bay to give it a try — just use a cheap soldering iron.

Eico Signal Generator Gets A Repair

June 23, 2020 by Al Williams 5 Comments

The Eico model 377 was a pretty common audio signal generator. [The Radio Mechanic] picked one up from 1956 that was in reasonably good shape, and shares a teardown and repair of the unit that you can see in the video below. The device could produce sine and square waves using a few tubes.

The unit was a bit different inside than expected because there were several versions made that shared the same model number. The bottom of the case had some goo in it, which is never a good sign. Unsurprisingly, the culprit was an old capacitor.

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Repairing A Workhorse Bench Meter

June 18, 2020 by Al Williams 23 Comments

In today’s market, and expensive high-precision bench meter will have a host of features: graphs, alarms, averaging, and more. It will probably even use an operating system. However, old meters can still get the job done at a price that you can actually afford. A case in point is the Fluke 8842A, solid meters with 5.5 digits of resolution and the ability to do two or four wire resistance measurements. They are built like tanks and are surprisingly affordable, especially if you consider what they went for when new. [Illya Tsemenko] recently updated a log about repairing such a meter, and there is a lot of good information about them if you own one or are thinking about one.

The biggest problem with repairing these meters is that there are several custom parts including the display that are essentially unavailable. For that reason, [Illya] took a meter with a broken display and used it to source parts for another meter.

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Time Enough At Last: Reviving An Heirloom Typewriter

May 4, 2020 by Erin Pinheiro 28 Comments

You may find yourself living in interesting times. The world we knew two months ago is gone, and there is time enough at last, to finally go through those projects we’ve been putting off for one reason or another. Today, I wanted to explore and possibly repair an old unidentified typewriter that belonged to my late aunt for many decades.

A small disclaimer though, I am not an avid typewriter collector or connoisseur. I enjoy looking at them and using them, but by no stretch of the imagination I want to claim to be an expert in their history or inner workings — I’m a hacker after all. What follows is a layman’s adventure into her first typewriter repair, an exciting tale that explores typewriter anatomy and troubleshooting. Let’s dig in.

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