A troublesome Triple-Z80 arcade board requires negative voltage for audio output

Vintage Arcade Used Negative Voltage To Turn Volume Up To 11

October 27, 2021 by 50 Comments

When [Nicole Express] got her hands on the logic board for the 1986 SNK arcade game Athena, she ran into a rather thorny problem: The board expected to be fed negative five volts! [Nicole]’s analysis of the problem and a brilliant solution are outlined in her well written blog post.

[Nicole]’s first task was to find out which devices need negative voltage. She found that the negative five volts was being fed through a capacitor to the ground pins on the Mitsubishi M151516L, an obscure 12 W audio amplifier. After finding the data sheet, she realized something strange: the amp didn’t call for negative voltage at all! A mystery was afoot.

To fully understand the problem, she considered a mid-1980’s arcade and its cacophony of sounds. How would a manufacturer make their arcade game stand out? By making it louder, obviously! And how did they make their game louder than the rest?

The answer lays in the requirement for negative five volts. The amplifier is still powered with a standard 12 V supply on its VCC pin. But with ground put at -5 V, the voltage potential is increased from 12 V to 17 V without overpowering the chip. The result is a louder game to draw more players and their fresh stacks of quarters.

How was [Nicole Express] to solve the problem? ATX PSU’s stopped providing -5 V after the ISA slot disappeared from PC’s, so that wouldn’t work. She could have purchased an expensive arcade style PSU, but that’s not her style. Instead, she employed a wonderful little hack: a charge pump circuit. A charge pump works by applying positive voltage to a capacitor. Then the capacitor is quickly disconnected from power, and the input and ground are flipped, an equal but negative voltage is found on its opposite plate. If this is done with a high enough frequency, a steady -5 V voltage can be had from a +5 V input. [Nicole Express] found a voltage inverter IC (ICL7660) made just for the purpose and put it to work.

The IC doesn’t supply enough power to get 12 W out of the amplifier, and so the resulting signal is fed into an external amplifier. Now [Nicole]’s arcade game has sound and she can play Athena from the original arcade board, 1986 style!

Arcades are few and far between these days, but that doesn’t mean you can’t introduce your young ones to the joys of dropping a quarter or two, or build a gorgeous oak Super Mario Bros cabinet complete with pixel art inlays. Do you have a favorite hack to share? Be sure let us know via the Tip Line!

a render of the curved bartop arcade machine in fusion 360

Bartop Arcade Machine That Isn’t Afraid Of Change

September 3, 2021 by 24 Comments

Arcade machines have a distinct look and feel with large imposing cabinets and smaller bartop machines that try to keep the look and feel of a traditional upright arcade cabinet while taking up less space. An entirely new aesthetic has been given for this engineering marvel of a bartop arcade that [DIY Engineering] has made. Gone is the expansive angular box, and in its place are sleek and slender curves. The key piece that makes this build work is the curved monitor.

He started with a detailed design in Fusion360 that really focused on the tools and techniques that [DIY Engineering] knew would work. The backbone of the device was formed from wooden dowels around which 3d printed parts slid on. To the sides of the dowels, two pieces of acrylic are screwed on to act as an LED diffusor. To that acrylic, two pieces of CNC’d red oak are attached with two arcade buttons for pinball-style actuation. Over the top, cast acrylic was heated and then bent into the desired shape with the help of a two-part mold press. The screen slotted right in perfectly. Part of the display at the top was reserved for a marquee, and the look is extraordinary with the dark acrylic. Ten arcade buttons and an eight-way joystick offer an array of options for input.

Internally, a temperature-controlled fan and a Raspberry Pi are running the show. Controls are wired as GPIO and read by the Pi. So naturally, the games on the SD card tend to look best on a long vertical screen: vertical shooters and the like.

Arguably, the best thing about this project isn’t just the execution (which is fantastic) but the look behind the curtain at the process. So many potential problems were solved in the modeling stage, and fabrication went fairly smoothly as a result (or so we think youtube hides a multitude of sins). The results speak for themselves, and we think this is an enviable arcading machine. [DIY Engineering] has mentioned providing files in the future for you to build your own. If perhaps it seems a little intimidating, why not give a smaller 3D printable bartop a try?

Video after the break.

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3D Printed Pi Arcade Is An Emulation Horn Of Plenty

January 20, 2021 by 19 Comments

Let’s be honest, building a home arcade cabinet isn’t exactly the challenge it once was. There’s plenty of kits out there that do all the hard work for you, and they even sell some pretty passable turn-key units at Walmart now. If you want to put a traditional arcade cabinet in your home, it’s not hard to get one.

Which is why this wild build by [Rafael Rubio] is so interesting. The entirely 3D printed enclosure looks like some kind of art piece from the 1970s, and is a perfect example of the kind of unconventional designs made possible by low-cost additive manufacturing. Building something like this out of wood or metal would be nightmare, especially for the novice; but with even a relatively meager desktop 3D printer you’re only a few clicks away from running off your own copy.

Removable side panels allow access to the electronics.

Inside the nautilus-like enclosure is a Raspberry Pi running Retropie, a 10″ LCD panel from Pimoroni, and a GeeekPi interface board that connects up to the 8-way joystick and arcade buttons. [Rafael] has included a Bill of Materials and an assembly overview that you can follow along with, though the cavernous internal dimensions of the enclosure certainly give you ample of room for improvisation if you’d rather blaze your own path.

Like the retro-futuristic computer terminals created by [Oriol Ferrer Mesià], this arcade machine completely reinvents a traditional design that most people take for granted. Is this layout actually better than the standard arcade cabinet? It’s not really our place to say. But it’s certainly a new and unconventional approach to “solved” problem, and that’s what we’re all about.

Solid Oak Arcade Cabinet: When Particle Board Won’t Do

January 8, 2021 by 25 Comments

Having an arcade cabinet of one’s own is a common dream among those who grew up during the video game arcade heyday of the 80s and early 90s. It’s a fairly common build that doesn’t take too much specialized knowledge to build. This cabinet, on the other hand, pulled out all of the stops for the cabinet itself, demonstrating an impressive level of woodworking expertise.

The cabinet enclosure is made with red oak boards, which the creator [Obstreperuss] sawed and planed and then glued together to create the various panels (more details are available on his Imgur album). The Mario artwork on the sides and front aren’t just vinyl stickers, either. He used various hardwoods cut into small squares to create pixel art inlays in the oak faces. After the fancy woodwork was completed, the build was finished out with some USB arcade controllers, a flat-panel screen, and a Raspberry Pi to run the games.

While the internals are pretty standard, we have to commend the incredible quality of the woodworking. It’s an impressive homage to classic arcade machines and we wouldn’t mind a similar one in our own homes. If you’re lacking the woodworking equipment, though, it’s possible to get a refined (yet smaller) arcade cabinet for yourself with a 3D printer instead.

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Toddler Arcade Cabinet Is A Stand-Up Job

October 6, 2020 by 6 Comments

A few years ago, [Mark] built an arcade cabinet into a low table. But once his new gaming buddy [Grayson] came along and started crawling, it wasn’t practical to have a low, pointy table around. Trouble is, [Mark] had already given [Grayson] his first taste with a Thomas the Tank Engine game. Since the kid was hooked, [Mark] rebuilt the table arcade into a toddler-sized arcade cabinet that they can both use.

The brain — a Raspberry Pi running RetroPie — should be familiar to most of our readers. [Mark] found the perfect crappy old monitor when they were upgrading at his office, and found some nice speakers to give it good bass. We love the details like the chrome edging, and especially the kick bar/footrest along the bottom. It can be difficult to decide how to decorate a multi-arcade cabinet, so [Mark] went the sticker bomb route with 700 of them randomly distributed and safe from toddler wear and tear under five coats of clear wood varnish.

We think this looks great, especially since [Mark] doesn’t have a workshop and cut all that MDF by hand on a jigsaw in the kitchen. Check out the happy train engineer after the break.

Maybe once [Grayson] is old enough to break tablets, [Mark] can build a gaming tab-inet out of it. Just sayin’.

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Miniature Star Wars Arcade Lets You Blow Up The Death Star On The Go

August 12, 2020 by 10 Comments

If you have fond childhood memories of afternoons spent at the local arcade, then you’ve had the occasional daydream about tracking down one of those old cabinets and putting it in the living room. But the size, cost, and rarity of these machines makes actually owning one impractical for most people.

While this fully functional 1/4th scale replica of the classic Star Wars arcade game created by [Jamie McShan] might not be a perfect replacement for the original, there’s no denying it would be easier to fit through your front door. Nearly every aspect of the iconic 1983 machine has been carefully recreated, right down to a working coin slot that accepts miniature quarters. Frankly, the build would have been impressive enough had he only put in half the detail work, but we certainly aren’t complaining that he went the extra mile.

[Jamie] leaned heavily on resin 3D printed parts for this build, and for good reason. It’s hard to imagine how he could have produced some of the tiny working parts for his cabinet using traditional manufacturing techniques. The game’s signature control yoke and the coin acceptor mechanism are really incredible feats of miniaturization, and a testament to what’s possible at the DIY level with relatively affordable tools.

The cabinet itself is cut from MDF, using plans appropriately scaled down from the real thing. Inside you’ll find a Raspberry Pi 3 Model A+ running RetroPie attached directly to the back of a 4.3 inch LCD with integrated amplified speakers. [Jamie] is using an Arduino to handle interfacing with the optical coin detector and controls, which communicates with the Pi over USB HID. He’s even added in a pair of 3,000 mAh LiPo battery packs and a dedicated charge controller so you can blow up the Death Star on the go.

Still don’t think you can fit one in your apartment? Not to worry, back in 2012 we actually saw somebody recreate this same cabinet in just 1/6th scale.

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Putting An Arcade Cabinet Inside Of An NES Controller

May 1, 2020 by 23 Comments

The arcade game shoehorned into an original Nintendo Entertainment System controller from [Taylor Burley] is certainly made slightly easier by its starting with one of those miniature cabinets that are all the rage now, but since he’s still achieved the feat of an entire arcade game in a controller we still stand by the assessment in our title.

In fact, he’s put not one but four arcade games into the controller. The board that [Taylor] liberated from the miniature game system can actually be switched between the onboard games by shorting out different pads on the PCB. Normally this would be done during manufacture with a zero-ohm resistor, but in this case, he’s wired the pads out to a strip of membrane keypad liberated from an LED remote control. By holding a different button while powering on the system, the user can select which of the games they want to boot into.

The original buttons and directional pad have been preserved, and in the video after the break, [Taylor] shows how he wires them into the arcade PCB. The Start and Select buttons had to go since that’s where the tiny color LCD goes now, but they wouldn’t have been used in any of these games anyway. With the addition of a small battery pack and charge controller, this build is a clever way to take several classic arcade titles with you on the go.

With the growing popularity of these tiny arcade cabinets, we’ve seen a number of hackers tearing into them. The work that [wrongbaud] has done in modifying them to run other ROMs is not to be missed if you’re looking at building a project using one of these little bundles of nostalgia.

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