Portable Commodore 64 Lives!

November 27, 2022 by Al Williams 17 Comments

When you think of a luggable computer, you might think of the old Compaq or — if you are old enough — a Kaypro. But you don’t see as many Commodore SX-64 computers. [The 8-Bit Guy] has wanted one for a while and finally got one, but it wasn’t working. No problem! Just fix it!

The device actually looks sleek compared to some other portables of the era and had a color screen, but — probably due to the price — they didn’t sell very well. The outside of the device looked pretty clean other than some loose screws and clips. The space key was quite yellow but at least there was a keyboard cable which is nearly impossible to find anymore.

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A working, partially disassembled thermal camera

Cheap Display Fix Brings Thermal Camera Back To Life

November 20, 2022 by Robin Kearey 5 Comments

When it comes to repairability of electronic devices, much depends on how helpful the original manufacturer is. Some make repairs very easy by publishing detailed service manuals and selling spare parts. Others keep everything under wraps to protect their intellectual property, turning even a supposedly simple fix into a reverse engineering ordeal. When [BuyItFixIt] got his hands on a FLIR multimeter-thermal camera combination instrument with a broken display, he quickly found that FLIR was firmly in the “all our designs are top secret” camp and wouldn’t even tell him what kind of display they had used.

Not to be deterred, [BuyItFixIt] took the meter apart and tried to find out what was going wrong. The signals from the microprocessor seemed to reach the display OK, so the fault was somewhere in the screen itself. The display’s part number didn’t return any useful results online, but AliExpress did have a very similar-looking display available with a slightly different part number. This display seemed to work at first, but the instrument then got caught in a boot loop.

Unlike FLIR, the supplier of the replacement display was happy to supply datasheets, and even had one available for the original FLIR part. With this new information [BuyItFixIt] was able to deduce that the new screen didn’t output one signal that the processor expected to see, causing it to reset itself. A simple workaround was to connect the corresponding pin to a PWM signal from the backlight controller, which fooled the CPU into thinking the proper display was connected.

In this case, a $12 display and a single piece of wire were enough to bring an expensive instrument back to life, but things are not always that simple. More complex machines can take weeks to debug, even if parts are available. If not, you might even need to design your own. Continue reading “Cheap Display Fix Brings Thermal Camera Back To Life” →

A PCB with several points highlighted by a projection system

Augmented Reality Workbench Helps You To Debug Your Boards

November 18, 2022 by Robin Kearey 17 Comments

No matter how advanced your design skills, the chances are you’ll need to spend some time chasing bugs in your boards after they come back from the assembly house. Testing and debugging a PCB typically involves a lot of cross-checking between the board, the layout and the schematic, which quickly becomes tiresome even for mildly complex designs. To make this task a bit easier, [Ishan Chatterjee] and colleagues at the University of Washington have designed the Augmented Reality Debugging Workbench, or ARDW for short.

The ARDW is a setup consisting of a lab workbench with an antistatic mat, a selection of measurement instruments and a PC. You can simply place your board on the bench, open the schematic and layout in KiCAD and start measuring and debugging your design as you normally would, but the real magic happens when you select a new icon in KiCAD that exports the schematic and layout to the ARDW system. From that moment, you can select components in your schematic and have them highlighted not only on the layout, but on the physical board in front of you as well. This is perhaps best demonstrated visually, as the team members do in the video embedded below.

The real-life highlighting of components is achieved thanks to a set of cameras that track the motion of everything on the desk as well as a video projector that overlays information on top of the PCB. All of this enables a variety of useful debugging features: for example, there’s an option to highlight pin one on all components, enabling a simple visual check of each component’s orientation. You can select all Do Not Populate (DNP) instances and immediately see if all highlighted pads are empty. If you’re not sure which component you’re looking at, just point at it with your multimeter probe and it’s highlighted on the schematic and layout. You can even place your probes on a net and automatically log the voltage for future reference, thanks to a digital link between the multimeter and the ARDW software.

In addition to designing and building the ARDW, the team also performed a usability study using a group of human test subjects. They especially liked the ability to quickly locate components on crowded boards, but found the on-line measurement system a bit cumbersome due to its limited positional accuracy. Future work will therefore focus on improving the resolution of the projected image and generally making the system more compact and robust. All software is freely available on the project’s GitHub page, and while the current system looks a little complex for hobbyist use, we can already imagine it being a useful tool in production environments.

It’s not even the first time augmented reality has been used for PCB debugging: we saw a somewhat similar system at the 2019 Hackaday Superconference. AR can also come in handy during the design and prototyping phase, as demonstrated by this AR breadboard.

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Bringing Up An Old Motherboard Is A Delicate Process

November 12, 2022 by Dan Maloney 12 Comments

If you were around for the early days of the personal computer revolution, you’ll no doubt recall the excitement every time IBM announced a new version of its beige boxes. For a lot of us, the excitement was purely vicarious, for despite the “personal” moniker, mere mortals could rarely afford a branded IBM machine. But it was still cool to keep track of the latest releases, and dream of the days when cheap clones would make it possible to play.

[Anders Nielsen]’s recent find of an original IBM Model 5160 motherboard sort of echoes that long-ago excitement, but in a different way. This board, from a PC XT built in 1984, was in unknown condition upon arrival, so [Anders] set about a careful process to try to bring the board back to life. A quick visual inspection leaves one with a sense of both how much things have changed, and how much they’ve stayed the same. Aside from the big 40-pin DIP 8088 CPU and the BIOS ROMs, the board is almost completely populated with discrete logic chips, but at the same time, the basic footprint of a motherboard has changed very little.

The bring-up process in the video below includes checks of all the power rails for shorts, which ended up being a good call — drat those tantalums. After fixing that issue, [Anders] had a bit of trouble getting the board to POST, and eventually resorted to dumping the BIOS ROMs and inspecting the contents. One of the chips had picked up a case of the scramblies at some point, which was easy enough to fix thanks to images of the 5160 ROMs available online. We thought the trick of using a 64k ROM and just writing the BIOS image twice was pretty clever.

In the end, the board came up, although without video or keyboard — that’s for another day. Can’t find your own PC XT motherboard to play with? Then maybe you can just build one.

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Computer Space Flies Again

November 10, 2022 by Jonathan Bennett 11 Comments

[Sean] from Classic Arcade Repairs fixes classic arcade machines, and he got a request to repair a very special machine. It’s Computer Space, the first commercial arcade cabinet ever made, and loosely based on Spacewar! This grand-daddy of coin-op was a literal barn find, and was in pretty bad shape after sitting for years. All the parts appeared to be original, making them 50 years old. As you can imagine, that combination didn’t bode well for the health of the components. There’s a couple hours of footage here, but it’s invaluable troubleshooting advice, and very cool to see such an old machine being worked on.

Part one is the intro, and [Sean] started with an HP logic analyzer, just probing the many TTL chips on the board looking for floating or otherwise suspicious outputs. Figure out the obviously faulty chips and replace each with a socket and new chip. Just about every diode in the machine needed replacing.

Part two of the repair starts with a broken trace repair, and the discovery that all the ceramic capacitors on the boards were leaky. The interesting thing is that a multimeter tested those caps as having the correct capacitance, but a dedicated leak tester discovered the problem.

Part 3 shows the process of running the remaining chips through a logic tester, which found more problematic ICs. In some cases, a chip would only sometimes test as working. And strangely, one of the new, replacement chips turned out to have a problem. Though as a commenter pointed out, it could be a falling edge vs rising edge variation of the logic chips to blame. Or maybe the new chips were counterfeit. Hard to nail down.

Part 4 starts with a gotcha moment, where one of the first repairs to the board was a misstep. What appeared to be a damaged trace, was actually a factory modification (a bodge cut?). Then a lucky break really helped out, where only half of one of the 7476 chips was in use, and one of the chips on hand was only half working. Put the dead bit into the unused slot, and the machine really started to behave.

Part 5 is the victory lap, where all the components finally arrived, and everything starts working on the bench. How cool to see the old machine bleeping and blooping again.

Photo of the back of a slingbox appliance, with ports shown and arrows going to them describing what each of the ports does.

Slingbox Getting Bricked – You Have Less Than 24 Hours

November 8, 2022 by Arya Voronova 41 Comments

The Slingbox devices used to let you catch up with the programming on your TV when you weren’t near it, using your Internet-connected mobile device. As cable TV became less popular, their business model faded away, and in 2020, they scheduled a service shutdown for November 9th, 2022. If you own a Slingbox, it’s getting bricked tomorrow – for those reading this in EU, that’ll be today, even. Do you have a Slingbox? You might still be able to repurpose it, let’s say, for local media streaming – but only if you waste no time.

[Gerry Dubois] has been developing the “Slinger” software for the past few months, a small app you run locally that proxies commands and video for your Slingbox, thanks to reverse-engineering communications with Slingbox servers. However, it needs a “hardware password” alphanumeric string, that you need to get from the Slingbox service web interface – which is to be promptly shut down. If you think you might have a use for what’s essentially a network-connected analog/digital video capture card with decent hardware, the GitHub repo has a lively discussion tab for any questions you might have.

One one hand, Slingbox shouldn’t be bricking the devices in a way that requires you act fast – perhaps, releasing a final update that makes the device hacker-friendly, like O2 did with their Joggler appliance back in the day, publishing the hardware documentation, or at least setting up a service up that lets anyone retrieve their hardware password indefinitely. On the other hand, at least they gave us two years’ notice, something less than usual – the amount of time between bricking and an announcement can even be a negative number. For those of us stuck with no operational device, a hardware exploration might be in order – for instance, we’ve torn down the Sling Adapter and even ran simple custom code on it!

Cheap Scope Troubleshoots Commodore

November 8, 2022 by Al Williams 17 Comments

[Adrian] had a Commodore computer to fix and decided to see how his latest tiny portable scope would work. He paid $57 for the tiny little test instrument although the current price seems higher. It claims to have 120MHz bandwidth along with 500 megasamples per second. There are several versions with different claimed specs, but we did find a similar device for under $60. You can see the unboxing and how it worked in the video below.

Of course, these kinds of instruments often overstate their specs, and [Adrian] was also suspicious. One odd feature of the device is it can echo its output to an NTSC video output so you can send the screen to an external monitor.

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