Repairing A Samsung 24″ LCD Monitor With Funky Color Issues

January 16, 2025 by Maya Posch 21 Comments

Dumpster diving is one of those experiences that can net you some pretty cool gear for a reasonable price. Case in point the 24″ Samsung S24E650XW LCD monitor that [MisterHW] saved from being trashed. Apparently in very good condition with no visible external damage, the unit even powered up without issues. It seemed like a golden find until he got onto the Windows desktop and began to notice quaint red shimmering in darker areas and other issues that made it clear why the monitor had been tossed. Of course, the second best part about dumpster diving is seeing whether you can repair such issues.

Prior to disassembly it had been noted that percussive maintenance and bending of the frame changed the symptoms, suggesting that something was a bit loose inside. After taking the back cover and shielded enclosure off, a quick visual inspection of the boards and cables quickly revealed the likely suspect: broken traces on one of the cables.

Apparently somewhere during the assembly step in the factory the cable had been pushed against the PCB’s edge, causing the initial damage. Based on the listed assembly date the monitor had only been in use for a few years before it was tossed, so likely the symptoms would have begun and worsened as one after another of the traces gradually cracked and broke due to vibrations, thermal expansion, etc.

This issue made fixing the monitor very simple, however, assuming a suitable replacement cable could be found. The broken cable is a 30P 1.0 pitch PFC, with EBay throwing up a cable with similar specs for a Thomson brand TV. One purchase and anxious wait later, the replacement cable was installed as in the featured image alongside the old cable. Perhaps unsurprisingly it restored the monitor to full working order, demonstrating once again that dumpster diving is totally worth it.

Repairing A Real (and Broken) Apollo-era DSKY

January 14, 2025 by Maya Posch 6 Comments

Presumably the same DSKY unit installed in the simulator at MIT.

The Display/Keyboard unit – DSKY for short – is the primary way that Apollo-era astronauts communicated with the onboard computers. Not all DSKYs ended up in space, however, with the MIT hosting a simulator that features one of these units. Unfortunately the unit that ended up at [CuriousMarc]’s lab had seen better days, with the assumption being that it was the same DSKY that was installed in a photo of the old simulator. In addition to the busted EL display and two (improper) replacement keys, the insides show signs of damaged modules and possibly worse.

Without bothering to hook the unit up to the (previously restored) guidance computer, a full teardown was begun to assess the full extent of the damage. Considering that the DSKY uses latching relays for memory and two modules were ominously marked as being defective, this made for a tense wait as the unit was disassembled.

Fortunately making new DSKY-style EL displays has first been replicated in 2019, meaning that a replacement is possible. Perhaps surprisingly, the busted display still fires up in the test rig, as a testament to how robust the technology is. At the end of the teardown, the assessment is that the unit can be restored to its original condition, which will be done in the upcoming videos in this series.

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Broken USB Lamp Saved With A Bit Of Woodworking

January 1, 2025 by Tom Nardi 1 Comment

For many of us, when we think of creating a custom enclosure, our minds immediately go towards our 3D printer. A bit of time in your CAD program of choice, and in an hour (or several), you’ve got a bespoke plastic box. A hacker’s dream come true.

But extruded plastic is hardly perfect. For one thing, you might want a finished piece that looks a little more attractive on your desk. Which is why we appreciate this quick hack from [Tilma]. When faced with a broken LED light and minimal equipment, he decided to transplant the repaired electronics into a scratch-built wooden frame that not only looks better than the original, but is more functional.

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Repairing A BPS-305 30V Bench Power Supply

December 31, 2024 by Maya Posch 6 Comments

When [Tahmid Mahbub] recently reached for his ‘Lavolta’ BPS-305 bench supply, he was dismayed to find that despite it being a 30V, 5A-rated unit, the supply refused to output more than 15V. To be fair, he wasn’t sure that he had ever tried to push it beyond 15V in the years that he had owned it, but it had better live up to its specs. Ergo out came the screwdriver to open the power supply to see what had broken, and hopefully to fix it.

After some more probing around, he discovered that the unit had many more issues, including a highly unstable output voltage and output current measurement was completely wrong. Fortunately this bench power supply turns out to be very much like any number of similar 30V, 5A units, with repair videos and schematics available.

While [Tahmid] doesn’t detail his troubleshooting process, he does mention the culprits: two broken potentiometers (VR104 and VR102). VR104 is a 5 kOhm pot in the output voltage feedback circuit and VR102 (500 Ohm) sets the maximum output current. With no 500 Ohm pot at hand, a 5 kOhm one was combined with a 470 Ohm resistor to still allow for trimming. Also adjusted were the voltage and current trimpots for the front display as they were quite a bit off. Following some testing on the reassembled unit, this power supply is now back in service, for the cost of two potentiometers and a bit of time.

The Mystery Of The Messed-Up Hammond X5

December 24, 2024 by Elliot Williams 4 Comments

[Filip] got his hands on a sweet old Hammond X5 organ, but it had one crucial problem: only half of the keys worked. Each and every C#, D, D#, E, F, and F# would not play, up and down the keyboard, although the other notes in between sounded just fine.

Those of you with an esoteric knowledge of older electric organs will be saying “it’s a busted top-octave generator chip”, and you’re right. One of the TOGs worked, and the other didn’t. [Filip] rolled his own top-octave generator with a Pico, in Python no less, and the old beauty roared to life once more.

But what is a top-octave generator, you may ask? For a brief period of time in the early 70s, there were organs that ran on square waves. Because a musical octave is a doubling or halving of frequency, you can create a pitch for every key on the organ if you simply create one octave’s worth of pitches, and divide them all down using something as simple as a binary counter IC. But nobody makes top-octave chips any more.

Back in 2018, [DC Darsen] wrote in asking us if we knew about any DIY top-octave designs, and we put out an Ask Hackaday to see if you all could make a top-octave generator out of a microcontroller. We got a super-optimized code hack in response, and that’s worth checking out in its own right, but we always had the nagging suspicion that a hardware solution was the best solution.

We love how [Filip]’s design leans heavily on the Pico’s programmable input/output hardware modules to get the job done with essentially zero CPU load, allowing him to write in Python and entirely bypassing the cycle-counting and assembly language trickery. The voltage shifters and the switchable jumpers to swap between different top-octave chip types are a nice touch as well. If you have an organ that needs a top-octave chip in 2024, this is the way we’d do it. (And it sounds fantastic.)

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Fixing 1986 Sinclair Spectrum+2 With A High-Score Of Issues

December 19, 2024 by Maya Posch 6 Comments

The Sinclair ZX Spectrum+2 was the first home computer released by Amstrad after buying up Sinclair. It’s basically a Sinclair ZX Spectrum 128, but with a proper keyboard and a built-in tape drive. The one that [Mark] of the Mend it Mark YouTube channel got in for repair is however very much dead. Upon first inspection of the PCB, it was obvious that someone had been in there before, replacing the 7805 voltage regulator and some work on other parts as well, which was promising. After what seemed like an easy fix with a broken joint on the 9 VDC input jack, the video output was however garbled, leading to the real fault analysis.

Fortunately these systems have full schematics available, allowing for easy probing on the address and data lines. Based on this the Z80 CPU was swapped out to eliminate a range of possibilities, but this changed nothing with the symptoms, and a diagnostic ROM cartridge didn’t even boot. Replacing a DS74LS157 multiplexer and trying different RAM chips also made no difference. This still left an array of options on what could be wrong.

Tracking down one short with an IC seemed to be a break, but the video output remained garbled, leaving the exciting possibility of multiple faults remaining. This pattern continues for most of the rest of the video, as through a slow process of elimination the bugs are all hunted down and eliminated, leaving a revived Spectrum+2 (and working tape drive) in its wake, as well as the realization that even with all through-hole parts and full schematics, troubleshooting can still be a royal pain.

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Emulating The Battery Controller In An Ancient Acer PDA

December 16, 2024 by Lewin Day 11 Comments

[Mark B] had a problem. He’d come into possession of an Acer N30 PDA, sans batteries. He couldn’t just throw any old cells in, since the unit expected to communicate with an onboard controller chip in the original pack. What ensued was his effort to emulate the original battery controller hardware. This is classic Hackaday right here, folks.

Just wiring in typical Li-Ion voltages to the PDAs battery pins wasn’t enough to make this Windows CE device happy. The device kept fleeing to sleep mode, thinking the battery was faulty or very low. Eventually, inspecting the motherboard revealed the PDA hosted a BQ24025 charger IC from Texas Instruments. [Mark] surmised it was trying to communciate with a BQ26500 “gas gauge” IC from the original battery pack. Armed with that knowledge, he then set about programming an STM32 chip to emulate its behavior. He then successfully ported the functionality over to a CH32V003 microcontroller as well. Paired with a Nokia BL-5CT battery, he had a working portable power solution for his PDA.

It’s great to see ancient hardware brought back to functionality with some good old fashioned hacking. I’d hoped to do the same with my Apple Newton before someone nicked it from my lounge room, more’s the pity. If you’re rescuing your own beleaguered battery-powered portables, don’t hesitate to let us know!