Heathkit Tuner Saved From Junk Pile

April 4, 2026 by Al Williams 4 Comments

We miss the old Heathkit. You could build equipment that rivaled or even surpassed commercial devices. The cost was usually reasonable and, even if you could get by with less, the satisfaction of using gear you built yourself was worth a lot. Not to mention the knowledge you’d gain and your confidence in troubleshooting should the need arise. So we were jealous of [RCD66] when he found a Heathkit AJ-43C stereo tuner in the recycle bin.

As you can see in the video below, it needed a lot of love to get back to its former self. The device dates from around 1965, when the kit cost $130. In 1965, that was a lot of money. Back then, that would have bought you about four ounces of gold and would have been a great down payment on a $1,500 VW bug.

Things were a bit of a mess, so he removed all the parts and replaced most of them. Unsurprisingly, the electrolytic capacitors all tested bad. The transistors were all germanium, but if they tested good, his plan was to reuse them. There were several PCBs inside, and he made some changes, such as replacing the zener diode power supply with something more modern.

How did it sound? Watch the video and see for yourself. We usually like troubleshooting specific problems on gear like this, but in this case, it was probably smart to just do a total rework.

Heathkit had quite an origin story. This isn’t the first time we’ve seen someone strip and rebuild a Heathkit.

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Mercury Audio Cables, So Nobody Else Has To Do It

April 1, 2026 by Jenny List 64 Comments

We’ve seen our fair share of audiophile tomfoolery here at Hackaday, and we’ve even poked fun at a few of them over the years. Perhaps one of the most outrageously over the top that we’ve so far seen comes from [Pierogi Engineering] who, we’ll grant you not in a spirit of audiophile expectation, has made a set of speaker interconnects using liquid mercury.

In terms of construction they’re transparent tubes filled with mercury and capped off with 4 mm plugs as you might expect. We hear them compared with copper cables and from where we’re sitting we can’t tell any difference, but as we’ve said in the past, the only metrics that matter in this field come from an audio analyzer.

But that’s not what we take away from the video below the break. Being honest for a minute, there was a discussion among Hackaday editors as to whether or not we should feature this story. He’s handling significant quantities of mercury, and it’s probably not over reacting to express concerns about his procedures. We wouldn’t handle mercury like that, and we’d suggest that unless you want to turn your home into a Superfund site, you shouldn’t either. But now someone has, so at least there’s no need for anyone else to answer the question as to whether mercury makes a good interconnect.

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Fixing An Onkyo Receiver With Multiple Faults

March 7, 2026 by Maya Posch 12 Comments

Modern-day receivers are miracles of digital audio and video processing, but compared to their more analog brethren, they can come with a host of new and fascinating faults. The Onkyo TX-SA806 and SR806 receivers were released back in 2008, with [Tony359] recently getting the latter variant in for repair. Described as having weird digital distortion on the audio outputs, this particular issue got fixed by recapping the PCB with all the digital processing in the first video on this receiver, but this left the second issue unaddressed of a persistent hum, which is the topic of the second video on this repair.

Capacitor C5662 in the Onkyo TX-SR608 receiver with a slight bulge. (Credit: Tony359, YouTube) — Capacitor C5662 in the Onkyo TX-SR608 receiver with a slight bulge.

With the easy fix of recapping of the digital board already tried, next was a deep-dive into the receiver’s schematics to figure out where this low-frequency hum was coming from. With it sounding very much like mains frequency hum bleeding through, this was the starting point. Presumably somewhere on the power rails the normal filtering had broken down, so all rails had to be identified and checked for this interference.

With ripple on the 10V and 12V rails as well as the others seemingly in order, it wasn’t clear where the 100 Hz hum was coming from, but people on the BadCaps forum offered some help. After some back and forth it was deduced that the problem was the +15 VA rail, with heavy ripple on it due to a dead capacitor on the +22 V rail that comes straight from a transformer.

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Philco Bet The Farm On The Predicta… And Lost

February 27, 2026 by Al Williams 31 Comments

Philco was a common household brand for many years. The company started in 1892, making street lights. Then they pivoted to batteries. This was big business when early radios were all battery-operated. But in the 1920s, line-powered radios threatened to shrink their customer base, so they pivoted again. This time, they started making radios. So what happened? [The Last Shift] has the story, and you can see the video below.

Philco used advanced manufacturing techniques to make radios more affordable. By 1930, they were the number one radio maker in the world. After World War II, they moved into everything electric: mostly appliances, but also the new king of the electronics market, the television.

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HD On A VHS Tape? How Did They Do It?

February 20, 2026 by Jenny List 10 Comments

There was a period from the 1970s to the mid-2000s or so when a fixture underneath the family TV set was a VHS videocassette recorder. These were a masterpiece of cramming a color video signal into the restricted bandwidth of an affordable 1970s helical-scan tape deck, which was achieved by clever use of frequency shifting and FM carrier modulation. Very few of us will have had the ultimate iteration of the VHS format though, W-VHS, which managed the same trick but with HD video. But how? [Superchromat] is here with the answer.

W-VHS used a frequency modulated carrier, but instead of splitting luminance and chrominance in the frequency domain like its VHS ancestor, it did so in the time domain in the same way as some 1980s satellite TV standards did. Each line first contained the color information, then the brightness. Thus it sacrificed some color resolution and a little horizontal image resolution, but kept a much higher vertical image resolution. In the video below the break we go into significant detail about the compromises required to pull this off, and if you watch it through you’ll learn something about magnetic tape recording as well as FM.

The W-VHS standard is largely forgotten now as a last hurrah for the format, but it’s still in the sights of the VHS Decode project. The work in this video is helping them retrieve the highest quality images from these tapes, by capturing the raw RF from the heads and using DSP techniques to decode them.

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Wooden Case Makes A 2026 TV Stylish

February 8, 2026 by Jenny List 17 Comments

The middle of the 20th century produced a revolution in understated stylish consumer design, some of which lives on today. The reality of living in a 1950s or ’60s house was probably to be surrounded by the usual mess of possessions from many past decades, but the promise was of a beautiful sleek and futuristic living space. Central to this in most homes would have been the TV set, and manufacturers followed the trends of the age with cases that are now iconic. Here in 2026 we put up with black rectangles, but fortunately there’s Cordova Woodworking with a modern take on a retro TV cabinet.

We’ve put the build video below, and it’s a wonderfully watchable piece of workshop titillation in a fully-equipped modern shop. While we appreciate they’ve put the design up for sale, we think many Hackaday readers could come up with their own having already been inspired. One thing we notice over the originals is that they use “proper” wood for their case, when we know the ’60s version would have had veneer-faced ply or chipboard.

The result is a piece of furniture which nicely contains the modern TV and accessories, but doesn’t weigh a ton or dominate the room in the way one of the originals would have, much less emit that evocative phenolic hot-electronics smell. We’d have one in our living room right now. Meanwhile if you’d like a wallow in mid-century TV, we have you covered.

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A New Life For An Old Amplifier

January 14, 2026 by Jenny List 23 Comments

An audio amplifier was once a fairly simple analogue device, but in recent decades a typical home entertainment amplifier will have expanded to include many digital functions. When these break they are often proprietary and not easy to repair, as was the case with a broken Pioneer surround-sound device given to [Boz]. It sat on the shelf for a few years until he had the idea of a jukebox for his ripped CDs, and his returning it to life with a new main board is something to behold.

Internally it’s a surprisingly modular design, meaning that the front panel with its VFD display and driver were intact and working, as were the class AB amplifier and its power supply. He had the service manual so reverse engineering was straightforward, thus out came the main board in favor of a replacement. He took the original connectors and a few other components, then designed a PCB to take them and a Raspberry Pi Pico and DAC. With appropriate MMBASIC firmware it looks as though it was originally made this way, a sense heightened by a look at the motherboard inside (ignoring a couple of bodges).

We like seeing projects like this one which revive broken devices, and this one is particularly special quality wise. We’re more used to seeing it with gaming hardware though.