Reverse-Engineering Mystery TV Equipment: The Micro-Scan

September 3, 2025 by Donald Papp 12 Comments

[VWestlife] ended up with an obscure piece of 80s satellite TV technology, shown above. The Micro-Scan is a fairly plan metal box with a single “Tune” knob on the front. At the back is a power switch and connectors for TV Antenna, TV Set, and “MW” (probably meaning microwave). There’s no other data. What was this, and what was it for?

Satellite TV worked by having a dish receive microwave signals, but televisions could not use those signals directly. A downconverter was needed to turn the signal into something an indoor receiver box (to which the television was attached) could use, allowing the user to select a channel to feed into the TV.

At first, [VWestlife] suspected the Micro-Scan was a form of simple downconverter, but that turned out to not be the case. Testing showed that the box didn’t modify signals at all. Opening it up revealed the Micro-Scan acts as a combination switchbox and variable power supply, sending a regulated 12-16 V (depending on knob position) out the “MW” connector.

So what is it for, and what does that “Tune” knob do? When powered off, the Micro-Scan connected the TV (plugged into the “TV Set” connector) to its normal external antenna (connected to “TV Antenna”) and the TV worked like a normal television. When powered on, the TV would instead be connected to the “MW” connector, probably to a remote downconverter. In addition, the Micro-Scan supplied a voltage (the 12-16 V) on that connector, which was probably a control voltage responsible for tuning the downconverter. The resulting signal was passed unmodified to the TV.

It can be a challenge to investigate vintage equipment modern TV no longer needs, especially hardware that doesn’t fit the usual way things were done, and lacks documentation. If you’d like to see a walkthrough and some hands-on with the Micro-Scan, check out the video (embedded bel0w).

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A Label Printer Gets A New Brain

September 1, 2025 by Jenny List 9 Comments

The internals of a printer, whatever technology it may use, are invariably proprietary, with an abstracted more standard language being used to communicate with a host computer. Thus it’s surprisingly rare to see hacks on printers as printers, rather than printer hacks using the parts for some other purpose. This makes [Oelison]’s brain-swap of a Casio thermal label printer a welcome surprise, as it puts an ESP32 in the machine instead of whatever Casio gave it.

The value in the hack lies in the insight it gives into how a thermal printer works as much as it does in the ESP32 and the Casio, as it goes into some detail on the various signals involved. The strobe line for instance to enable the heater is a nuance we were unaware of. The resulting printer will lose its keyboard and display, but make up for it in connectivity.

Despite what we said earlier this isn’t the first label printer hack we’ve seen. A previous one was Linux-based though.

Why Super Mario 64 Wastes So Much Memory

August 28, 2025 by Maya Posch 44 Comments

The Nintendo 64 was an amazing video game console, and alongside consoles like the Sony PlayStation, helped herald in the era of 3D games. That said, it was new hardware, with new development tools, and thus creating those early N64 games was a daunting task. In an in-depth review of Super Mario 64’s code, [Kaze Emanuar] goes over the curious and wasteful memory usage, mostly due to unused memory map sections, unoptimized math look-up tables, and greedy asset loading.

The game as delivered in the Japanese and North-American markets also seems to have been a debug build, with unneeded code everywhere. That said, within the context of the three-year development cycle, it’s not bad at all — with twenty months spent by seven programmers on actual development for a system whose hardware and tooling were still being finalized, with few examples available of how to do aspects like level management, a virtual camera, etc. Over the years [Kaze] has probably spent more time combing over SM64‘s code than the original developers, as evidenced by his other videos.

As noted in the video, later N64 games like Legend of Zelda: Ocarina of Time are massively more optimized and streamlined, as lessons were learned and tooling improved. For the SM64 developers, however, they had a gargantuan 4 MB of fast RDRAM to work with, so optimization and memory management likely got kicked down to the bottom on the priority list. Considering the absolute smash hit that SM64 became, it seems that these priorities were indeed correct.

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JuiceBox Rescue: Freeing Tethered EV Chargers From Corporate Overlords

August 27, 2025 by Maya Posch 32 Comments

The JuiceBox charger in its natural environment. (Credit: Nathan Matias)

Having a charger installed at home for your electric car is very convenient, not only for the obvious home charging, but also for having scheduling and other features built-in. Sadly, like with so many devices today, these tend to be tethered to a remote service managed by the manufacturer. In the case of the JuiceBox charger that [Nathan Matias] and many of his neighbors bought into years ago, back then it and the associated JuiceNet service was still part of a quirky startup. After the startup got snapped up by a large company, things got so bad that [Nathan] and others saw themselves required to find a way to untether their EV chargers.

The drama began back in October of last year, when the North American branch of the parent company – Enel X Way – announced that it’d shutdown operations. After backlash, the online functionality was kept alive while a buyer was sought. That’s when [Nathan] and other JuiceBox owners got an email informing them that the online service would be shutdown, severely crippling their EV chargers.

Ultimately both a software and hardware solution was developed, the former being the JuicePass Proxy project which keeps the original hardware and associated app working. The other solution is a complete brain transplant, created by the folk over at OpenEVSE, which enables interoperability with e.g. Home Assistant through standard protocols like MQTT.

Stories like these make one wonder how much of this online functionality is actually required, and how much of it just a way for manufacturers to get consumers to install a terminal in their homes for online subscription services.

Very Efficient APFC Circuit In Faulty Industrial 960 Watt Power Supply

August 25, 2025 by Maya Posch 2 Comments

The best part about post-mortem teardowns of electronics is when you discover some unusual design features, whether or not these are related to the original fault. In the case of a recent [DiodeGoneWild] video involving the teardown of an industrial DIN-rail mounted 24 V, 960 Watt power supply, the source of the reported bang was easy enough to spot. During the subsequent teardown of this very nicely modular PSU the automatic power factor correction (APFC) board showed it to have an unusual design, which got captured in a schematic and is explained in the video.

Choosing such a APFC design seems to have been done in the name of efficiency, bypassing two of the internal diodes in the bridge rectifier with the external MOSFETs and ultrafast diodes. In short, it prevents some of the typical diode voltage drops by removing diodes in the path of the current.

Although not a new design, as succinctly pointed out in the comments by [marcogeri], it’s explained how even cutting out one diode worth of voltage drop in a PSU like this can save 10 Watt of losses. Since DIN rail PSUs rarely feature fans for active cooling, this kind of APFC design is highly relevant and helps to prevent passively cooled PSUs from spiraling into even more of a thermal nightmare.

As for the cause behind the sooty skid marks on one of the PCBs, that will be covered in the next video.

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How Intel’s 386 Protects Itself From ESD, Latch-up And Metastability

August 21, 2025 by Maya Posch 11 Comments

To connect the miniature world of integrated circuits like a CPU with the outside world, a number of physical connections have to be made. Although this may seem straightforward, these I/O pads form a major risk to the chip’s functioning and integrity, in the form of electrostatic discharge (ESD), a type of short-circuit called a latch-up and metastability through factors like noise. Shielding the delicate ASIC from the cruel outside world is the task of the I/O circuitry, with [Ken Shirriff] recently taking an in-depth look at this circuity in Intel’s 386 CPU.

The 386 die, zooming in on some of the bond pad circuits. (Credit: Ken Shirriff)

The 386 has a total of 141 of these I/O pads, each connected to a pin on the packaging with a delicate golden bond wire. ESD is on the top of the list of potential risks, as a surge of high voltage can literally blow a hole in the circuitry. The protective circuit for this can be seen in the above die shot, with its clamping diodes, current-limiting resistor and a third diode.

Latch-up is the second major issue, caused by the inadvertent creation of parasitic structures underneath the P- and NMOS transistors. These parasitic transistors are normally inactive, but if activated they can cause latch-up which best case causes a momentary failure, but worst case melts a part of the chip due to high currents.

To prevent I/O pads from triggering latch-up, the 386 implements ‘guard rings’ that should block unwanted current flow. Finally there is metastability, which as the name suggests isn’t necessarily harmful, but can seriously mess with the operation of the chip which expects clean binary signals. On the 386 two flip-flops per I/O pad are used to mostly resolve this.

Although the 386’s 1985-era circuitry was very chonky by today’s standards, it was still no match for these external influences, making it clear just how important these protective measures are for today’s ASICs with much smaller feature sizes.

Playing DOOM On The Anker Prime Charging Station

August 21, 2025 by Maya Posch 12 Comments

At this point the question is no longer whether a new device runs DOOM, but rather how well. In the case of Anker’s Prime Charging Station it turns out that it’s actually not too terrible at controlling the game, as [Aaron Christophel] demonstrates. Unlike the similar Anker power bank product with BLE and a big display that we previously covered, this device has quite the capable hardware inside.

Playing a quick game of Doom while waiting for charging to finish. (Credit: Aaron Christophel, YouTube) — Playing a quick game of *DOOM* while waiting for charging to finish. (Credit: Aaron Christophel, YouTube)

According to [Aaron], inside this charging station you’ll not only find an ESP32-C3 for Bluetooth Low Energy (BLE) duty, but also a 150 MHz Synwit SWM341RET7 (Chinese datasheet) ARM-based MCU along with 16 MB of external flash and 8 MB of external RAM. Both of these are directly mapped into the MCU’s memory space. The front display has a 200×480 pixel resolution.

This Synwit MCU is a bit of a curiosity, as it uses ARM China’s Star-MC1 architecture for which most of the information is in Chinese, though it’s clear that it implements the ARMv8-M profile. It can also be programmed the typical way, which is what [Aaron] did to get DOOM on it, with the clicky encoder on the side of the charging station being the sole control input.

As can be seen in the video it makes for a somewhat awkward playing experience, but far more usable than one might expect, even if running full-screen proved to be a bit too much for the hardware.

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