Fixing A Dodgy Cheap Audio DAC

July 9, 2026 by Jenny List 14 Comments

One of the attractions of buying at the bottom end of the electronics market by mail order from China is that you never quite know what will come your way. Sometimes it’s a diamond in the rough, while with others it’s a mess. Occasionally along comes something which should work but doesn’t, and that’s the moment when you wonder if you could fix it. [Nyanpasu64] had just such a device, an HDMI to VGA converter with audio that didn’t work. What could be wrong?

The HDMI to VGA chip has an onboard audio digital-to-analog converter (DAC), and it’s a delta-sigma design. This type of DAC is frequently used in audio applications because it works by shifting its switching frequency many times higher than the input sample rate, thus reducing considerably the distortion. This one wasn’t performing as advertised though, and the problem turned out to be that switching frequency being all over the output. Clearly the filter wasn’t working, which led to the design of a new filter. The write-up is therefore an extensive dive into filter design, and in part also a discovery of the effect of impedance on them.

For a super-cheap module to cause so much work, one might ask why not simply spend a few more dollars and get a better one. But had they done that we wouldn’t have seen this write-up, so we’re sticking with team cheap.

We’ve looked at audio DACs, in the past.

Fixing An Elgato Cam Link’s USB Current Draw Issue

June 26, 2026 by Maya Posch 12 Comments

Recently [Bits und Bolts] found himself in a bit of a pickle, when on boot his PC would complain about a connected USB device drawing too much power, before shutting down again. After unplugging various USB devices, the problem was narrowed down to an Elgato Cam Link 4K video capture device.

Some prodding and poking around with a thermal camera on the disassembled device while powered showed that an onboard IC had sprung a power leak. Sadly, even asking nicely, Elgato support wasn’t going to provide board-level repair help, so this was left as an exercise to the owner.

Although the markings on the chip didn’t offer much help, it turns out that this is a more common issue, with a convenient repair guide by [Uldis Melderis] identifying the part as the TI TLV62585 buck regulator.

After purchasing a couple of spares, the defective IC could then be replaced. Following this a quick test showing decidedly less angry electrons. From there it was a matter of reassembling the device in its plastic case and seeing whether the PC was happier with the now hopefully fixed device, which fortunately turned out to be the case.

Any such analysis and repair obviously raises a number of questions, such as why these buck regulators are dying, and why you’re supposed to just toss out a $100 device instead of doing a repair involving a $0.20 part and a few minutes with a hot air gun.

Fixing A Warped Paperback Spine With Gentle Heating

June 25, 2026 by Maya Posch 10 Comments

Although paperbacks are a much-loved aspect of the literary world, they are not really intended to last the decades the way that hardcover books are. Beyond the typical ravaged covers, paperbacks also tend to suffer from a warped spine, where the formally flat spine gets a definite inwards curve due to the ravages of moisture, temperature, failing glue and the passing of time in general. If this bothers you, then [Book Care Studio] shows a simple technique using which these spines can be flattened again.

All that you need for this approach are two cutting boards and two clamps to provide some clamping force on the book, along with a heat gun and some patience.

The book is clamped between the two boards with the spine sticking out. By putting said spine flat on e.g. a table and pushing on the opposite side while alternatingly briefly releasing the clamps, the spine can be forced into a flatter state. Without forcing this and then flipping the paperback sandwich around to heat the spine with the heat gun, the glue of the binding in the spine can then be softened sufficiently that a few of these push-heat cycles should be enough to straighten the spine.

Other than rebinding the book as for example public libraries are wont to do with a hardcover conversion of flimsy paperbacks, this simple approach should clean up a ratty-looking paperback collection. While one can definitely argue that half the charm of old paperbacks are the wrinkles, curves and intense smell of acidifying paper, it’s always good to have options like this at one’s disposal.

Continue reading “Fixing A Warped Paperback Spine With Gentle Heating” →

Repairing A Pair Of Voodoo 2 GPUs For Some SLI Action

June 11, 2026 by Maya Posch 12 Comments

Well there's your problem. (Credit: Bits und Bolts, YouTube) — Well there’s your problem. (Credit: Bits und Bolts, YouTube)

Recently [Bits und Bolts] stumbled over a pair of Dragon 3000 branded 3dfx Voodoo 2 cards in his unfixed cards pile, and decided that the best course of action was to not only fix them, but also run them in SLI for some sweet Unreal Tournament action. Naturally, these cards being in the broken cards pile meant that he first had to figure out why they were broken and fix all issues.

The advantage of having two identical Voodoo 2 cards is of course that any missing components, like some resistors on one card, could be referenced on the other card. Beyond that it was mostly a matter of reflowing clearly corroded pins on the ICs and replacing damaged resistors and resistor arrays before the first tests could be run.

Using the mojo utility it was easy enough to spot that there were still some lingering issues, with clear issues visible in 3D games as well. These were tracked down to a dodgy pin on one of the texture mapping units (TMUs) that needed some more reflowing, and a very sneaky resistor array that was cracked but not obviously so until prodded with a multimeter.

With both cards now making happy noises when individually tested, it was time to go full SLI, fire up the Pentium 2 system and enjoy the glory of 24 MB of VRAM at high resolutions in Unreal Tournament. Considering that the bloke who had sent in these cards had found them while cleaning up a shed, it’s quite amazing how little rework was needed to once again party like it’s 1999.

Continue reading “Repairing A Pair Of Voodoo 2 GPUs For Some SLI Action” →

How The 2020s Chip Crisis Led To A Buggy Saleae Analyzer In 2026

June 9, 2026 by Maya Posch 36 Comments

For those of us old enough to remember the harrowing days of the early 2020s, alongside another major kerfuffle there was a complete breakdown in global supply chains that led to the 2020-2023 global chip shortage. Unsurprisingly, this pushed many hardware manufacturers into less orthodox approaches, massive BOM changes, and hurried redesigns. One of the results of this era found its way into the hands of the bloke over at the [Playduino] YouTube channel, who was mystified to find two bodge wires in his fancy Saleae logic analyzer.

The reason for popping open the LA was crosstalk between two channels, which was bad enough that it made the unit quite unusable for the intended task. After seeing the cut traces and bodge wires he initially assumed that since he bought it used that the previous owner had modified it, but said person denied having opened it since purchasing it from an official retailer.

This was when he emailed Saleae support to see whether they knew anything. Initially they denied knowing anything about such a modification, but then the CTO emailed back with a long and very detailed confession. As explained in the video, during the aforementioned chip crisis Saleae was forced to rapidly redesign their LAs to use whatever FPGAs and other parts they could still get their hands on.

An initial prototype unit passed their internal tests, so they had a first batch manufactured using PCBs from a different supplier. Despite sending the same Gerber files, the resulting PCBs had ground fill issues that necessitated the observed rework, but due to insufficient testing for crosstalk a total of 406 units made it into the wild.

Sadly he had to return the defective unit for a replacement, making it somewhat hard to let go of such a piece of history. That said, if you want to know whether you’re also one of the lucky remaining 405 LA owners, the CTO provided the affected serial number range: 00200026245 to 00200026675 are affected.

Continue reading “How The 2020s Chip Crisis Led To A Buggy Saleae Analyzer In 2026” →

Repairing A Apple PowerBook 150 With Serious Issues

June 7, 2026 by Maya Posch 2 Comments

Sometimes you purchase an old device that is very cheap for a good reason. So too with the 1995 Apple PowerBook 150 that [Hugh Jeffreys] purchased for a single Aussie buck back in 2018. After finally taking it off the shelf recently, the issues are very apparent. Without even trying to turn it on, the visible damage ranges from the display that’s gone full vinegar with wolverine scratches, to the snapped hinge. Naturally the HDD also turned out to be dead.

Without a functioning display there was little point in continuing, so the disassembly started there, revealing many broken plastic clips. The cause of the vinegar symptom is the degrading polarizer, which with some finesse can be removed like a thick screen protector. Fortunately, here it’s put on top of the glass layer of the display, so after peeling it off the remaining glue can be safely dissolved and scraped away.

Inside the case the RTC battery was found to have started leaking, causing corrosion and damaging a variety of important traces for the keyboard and display. All of this damage seemed fixable, but after a while the damage was just too severe. Fortunately he was able to obtain a replacement for the affected daughter PCB, which allowed the display to come back to life, so that a new polarizer could be installed after cutting a large sheet down to size.

A replacement hinge was then printed in PETG and glued to the part of the lid where it had broken off, while snapped plastic clips were reinforced with glue where they had hung on. Finally, the IDE HDD was replaced with a CF card via an IDE adapter and the entire system reassembled.

Unfortunately [Hugh] wasn’t able to immediately source or create MacOS floppies with a version that the laptop wanted to install from, so that part couldn’t be tested yet, but there’s a good chance that this old PowerBook 150 has finally been cured of at least its biggest ills, without spending much more than the original asking price.

Continue reading “Repairing A Apple PowerBook 150 With Serious Issues” →

Fixing A Nintendo Game Boy Clone That Runs Too Fast

June 4, 2026 by Maya Posch 10 Comments

There’s no shortage of cloned Nintendo hardware out there, and most of it is pretty poor. A few are actually pretty interesting though, such as the GB Boy by Gangfeng, which takes real cartridges and thus in many ways should provide the original Game Boy Pocket experience with modern hardware. But as you might imagine, even the best of the clones comes with various technical issues at no additional charge — with this particular unit having a habit of running the game too fast. It’s an issue that [Sharopolis] addresses in a recent video with a partial fix.

As can be seen in the demonstration, it runs games just too fast to make it very usable or fun, hence why it sat in a drawer for a few years after purchasing off AliExpress. This raises the question of what’s wrong with these units, as others report similar issues with this and other ‘GB Boy’ variants.

Fortunately the unit is easy to open, revealing the PCB with a couple of chips on it, one marked KF2001 being the brains of the operation alongside two memory chips. The crystal resonator marked X1 for the main IC is rated for 5 MHz, whereas a quick look inside the Game Boy Pocket shows that its crystal resonator runs at 4.1943 MHz, which is a bit of a difference.

Because of how buying components and pricing works, [Sharopolis] ended up with a reel of 100 of replacement resonators with the right parameters for a drop-in replacement. After swapping the resonator, the GB Boy now does indeed run games at the right speed, but a new issue has now cropped up in the form of flicker on the display.

In the comments it’s suggested that replacing the cheap capacitors on the GB Boy’s board can help here, but it highlights just how these clone systems keep managing to snatch defeat from the jaws of victory by pairing what looks to be a pretty good IC with either the wrong or sub-par components.

Continue reading “Fixing A Nintendo Game Boy Clone That Runs Too Fast” →