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.
We should all be so lucky as [Salvaged circuitry], who scored a cheap Agilent oscilloscope from an online auction. Of course, its low price had a reason behind it, the ‘scope didn’t work. At fault was its power supply, the repair of which was documented in the video below.
These ‘scopes have relatively straightforward 12 V power supplies, extremely similar to off-the-shelf parts. The video is an interesting primer in switch-mode power supply repair, as the obvious failure of the filter capacitor and a MOSFET is traced further to the PSU controller chip. We see a new capacitor mounted proud of the board to reduce the risk of heat damage, and then some careful solder rework to save some lifted pads.
The result, a working oscilloscope. Maybe we’d have hacked in another 12 V supply, but given that this is a piece of test equipment perhaps it’s best to stay as close to the original spec as possible. As a parting shot he shows us an equivalent power supply, and promises us a side-by-side test in a future video.
[The Signal Path] snagged a fancy Rohde & Schwarz vector signal generator that can go up to 3.2 GHz, but sadly it wasn’t in working order. It powered up and even put out a 1 GHz signal, but the amplitude output was very wrong. Interestingly relative changes to the output were correct, it was just that the absolute output amplitude was off by quite a bit and changed with frequency. That started a detective job which you can follow along in the video below.
The instrument is pretty high-end, and did not report any problems even during self-check. This implied that all the internals were probably good and whatever was wrong probably lay close to the output. The service manual’s block diagram wasn’t terribly useful, especially given that all the processing portions appear to work well.
While repairing a real-time clock module for a 1970s HP computer that had been damaged by its leaky internal battery, [CuriousMarc] began to suspect that maybe the replacement clock chips which he had sourced from a seller in China were the reason why the module still wasn’t working after the repairs. This led him down the only obvious path: to decap and inspect both the failed original Ti chip and the replacement chip.
The IC in question is the Texas Instruments AC5948N (along with the AC5954N on other boards), which originally saw use in LED watches in the 1970s. HP used this IC in its RTC module, despite it never having been sold publicly. This makes it even more remarkable that a Chinese seller had the parts in stock. As some comments on the YouTube video mention, back then there wasn’t as much secrecy around designs, and it’s possible someone walked out of the factory with one of the masks for this chip.
Whether true or not, as the video (also included after the break) shows, both the original 1970s chip and the China-sourced one look identical. Are they original stock, or later produced from masks that made their way to Asia? We’ll probably never know for sure, but it does provide an exciting opportunity for folk who try to repair vintage equipment.
If you work on old radios, electronics is only one of the skills you need. The other is wood or metal working to restore the cabinets and chassis. However, more recent electronics have plastic and old plastic tends to turn yellow. [Odd Experiments] shows how to whiten plastic using a UV light source, aluminum foil, and hydrogen peroxide. Generally, ABS is the plastic at fault, especially those mixed with bromine as a fire retardant. You can see the results in the video below.
Note the peroxide in use was 12% — much stronger than what’s probably in your medicine cabinet. That’s usually only 3% solution, although you can get different strengths including some over 30% if you shop. However, if you search you’ll find that people have used 12%, 6%, and even 3% successfully, although we’d imagine it takes more time with 3%.
Combat robots have been a thing for a while, but we don’t normally get a close look at the end results of the sort of damage they can both take and deal out. [Raymond Ma] spent time helping out with season four of BattleBots and wrote about the experience, as well as showed several pictures of the kind of damage 250-pound robots can inflict upon each other. We’ve embedded a few of them here, but we encourage you to read [Raymond]’s writeup and see the rest for yourself.
The filming for a season of BattleBots is done in a relatively short amount of time, which means the pacing and repair work tends to be more fast and furious than slow and thoughtful. [Raymond] says that it isn’t uncommon for bots, near the end of filming, to be held together with last-minute welds, wrong-sized parts, and sets of firmly-crossed fingers. This isn’t because the bots themselves are poorly designed or made; it’s because they can get absolutely wrecked by the forces at play.
Combat robotics has been around for as long as people have been able to give a power tool some wheels and point it towards an opponent. Flying bots are even getting into the scene nowadays, with DroneClash leveraging the explosive growth of the drone industry to take the action into the air.
In this case, [Jamz] scored a LG 27UK650 monitor with a cracked display and a Dell OptiPlex 7440 “All-in-One” computer that was DOA. Separately these two pieces of gear were little more than a pile of spare parts waiting to be liberated. But if the control board could be salvaged from the monitor, and the working LCD pulled from the Dell…
After taking everything apart, [Jamz] made a frame for this new Frankenstein monitor using pieces of aluminum channel from the hardware store and 3D printed side panels. With the Dell LCD mounted in the skeletal frame, the control board from the LG monitor was bolted to the back and wired in. Finally the center section of the LG monitor’s back panel was cut out and mounted to the new hybrid display with a 3D printed frame.