Forgotten Control Panel Overlay – pt 1

The first arcade machine I purchased was this Leisure 2000 Neo-Geo MVS, containing a 4-slot MVS motherboard. It usually runs the following entertaining games: Metal Slug, Neo Turf Masters, Bubble Bobble and NeoGeo Cup 98. A Leisure 2000 is basically a cheap facsimile of the rather sort after Lordsvale cab. It’s pretty tidy inside, has a really crisp monitor and easy to move around the games room.

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Leisure 2000 Neo-Geo MVS

Looking closer at the control panel overlay (CPO) you can see that it’s seen better days. Someone’s idly picked at the edges and it’s also seen a long scrape across the front at some point.

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This CPO has seen better days!

I contacted MuddyMusic on the UKVac forum (he now runs the rather awesome Arcade Art Shop) and he made me a vector replacement but in the style of the more popular Lordsvale cab. It was delivered quickly, I looked at it and then it sat in the tube for about 4 years! Thanks to this blog it’s now out of the tube and sitting on the table currently being stretched out in preparation for fitting.

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A replacement CPO in the Lordsvale style

I’ll be sure to write-up how fitting the new CPO goes. I’ve got to completely remove the old one, requiring much elbow grease, and then slowly stick on the new one without trapping any air pockets. It’s a moderatly stressful process but watching a few YouTube videos should prepare me for it.

 

RaspberryPi Zero in a classic Xbox controller

Here’s a smaller project I completed in an evening or 2. I had intended to put a RaspberryPi Zero into a repro USB NES controller but, after finding I’d bought something that was completely unplayable (it kept pressing up alongside left or right), I ended up reading a blog by Terence Eden (@edent on Twitter) and modding a classic Xbox controller to do the job properly. Before the retro police turn up at my door I want to stress the original controller cable was broken and missing the end adapter!

USB modded controller containing the RaspberryPi

RetroPie handles all the emulation and loading ROMs via USB turns out to be pretty easy. I only loaded a handful of NES and classic arcade games as I’m not a huge gamer but do like a quick fix now and again.

I used a cheap dremal to cut a slit in the memory card slot so the pie could slot in and stay in without a large gaping hole. It also helps to keep the pie away from all the internal electrical components of the controller.

A snug fit!


The minor caveat to all this is that I tried to internalise the controller’s USB cable by hard wiring it directly to the pie’s data USB port but my soldering let me down and I pulled up the contact pad. I abandoned that more elegant solution but the upshot is that the Xbox controller will continue to work with other systems, such as a PC / Mac running MAME, and the data port on the pie will continue to work so I can add more ROMs.

Pros:

  • Easy to make project
  • Fast loading system
  • HDMI output is great for most modern TVs
  • Easy to add more games
  • Snug fit for the pie
  • Handles most old games

Cons:

  • Too many cables coming in /out (power, controller data, HDMI)
  • Restricted movement (tugging sideways pulls out HDMI)
  • No audio jack so sound must go via HDMI

In summary

I’m really pleased with it but am not really sure what I’ll do with it in the long-term. It was a nice project to work on but now it’s probably going to sit on a shelf. Maybe I’ll give it away or send it to The Centre for Computing History in Cambridge to have as an interactive example of what a pie can do for their programming classroom.

Vector arcade test bench – pt 2

This is a continuation of the project to build a working vector arcade test bench. In part 1 I introduced my 1979 Asteroids arcade machine, covered the Atari powerbrick that would power such a machine, the fact I’d picked up a  dilapidated spare, how I’d replaced some of the major components that were dead or dying, and the tasty paint job I gave it.

If you have little knowledge of the internals of classic Atari arcade machines then you might reasonably think that the next stage is to attach a game PCB to the powerbrick but there’s (un)fortunately more to it then that!

Introducing the Atari Audio Regulator PCB (AR and ARII in this case)IMG_1007.JPG

The AR is essentially a board dedicated to amplifying the game sound (as the name might suggest) but additionally it regulates a number of voltages for the main game PCB. It’s another part of the power system that Atari decided to separate out and which seems, for the most part, to have been a pretty good idea. If a fault developed on one of these relatively cheaper boards than an engineer could simply swap it out and keep the game running without touching the game board that included more expensive components such as ICs. Atari repurposed the AR board throughout their early games and, as the different games required different sets of voltages, made different revisions of it as they went along. There’s 1 or 2 versions of the AR1, about 6 or 7 AR2 variants and a handful of revisions of the AR3. The AR2 is the type that supports most number of classic cabs, being backward compatible with game PCBs that required the AR1, with, from memory, version ‘-02’ of the AR2 being the most compatible (on the left in the picture above) as it’s fully populated with components.

The main issue with these boards is that Atari tried to make them too clever by sticking in a ‘sense’ circuit. This circuit is meant to monitor the voltage level on the game PCB and, if it changes, take action by raising the voltage to the board. In the early days I’m sure it helped make the games more reliable but, over 35 years later, it’s not really doing what was intended. As the edge connector on the game PCB ages its contacts become less perfect and the power transfer therefore diminishes resulting in a lower voltage getting to the board. As the sense circuit attempts to compensate for the lower voltage by increasing the voltage it sends to the game pcb, it exasperates the situation, heating up the edge connector which then decreases the electrical contact. A death-loop ensues and the end result is high voltage on the 5V line (probably 9V+) and a couple of components on the AR board breaking and / or bursting into flame. The solution is to keep the game edge connector properly maintained, fit a set of ‘Guddler-approved’ jump leads between the game PCB test points and the AR’s test points (to bypass the aging edge connector), and / or, for a more permanent solution, perform the ‘sense mod’.

I’ve replaced the burned transistor at J6, patched the broken track and put the sense mod in by joining pin 1 & 2 and 3 & 6 at J7:

J6 shows high-voltage damage and J7 is sense modded

The sense mod is pretty simple in that you just solder two pairs of points together on the AR board so it ends up analysing the voltage it produces instead of the voltage coming back from the game PCB. By reading the AR’s own generated voltage it makes no further adjustments to the output voltage as it reads it as spot on. I decided to go down the sense mod route for my own AR2 and will also be acquiring the ‘Guddler-approved’ jump leads in the near future.

Some excellent links about AR sense mod:

 

 

Vector arcade test bench – pt 1

I’ve not long been the owner of a classic Atari Asteroids arcade machine and, like all things old, it needs proper maintenance. I’ve taken it upon myself to learn the machine inside out starting with the PCB and how to manage its upkeep.

 

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Asteroids 1979

 

The awesome thing about classic Atari games is that they are amazingly well documented and nearly every part is replaceable if it fails. The challenge comes in finding out what has failed. After a week I lost the ‘thump-thump-thump’ heartbeat that sounds throughout play. I checked the schematics, read a few posts on UKVac and then located the IC that commonly fails. A quick eBay purchase of the (now socketed) IC followed by some rusty soldering resulted in the sound coming back again. A couple of months later though the machine has developed another fault and is constantly resetting (watch-dogging as it’s known in arcade repair land). So what next?

I was fortunate enough to come across a sale of classic arcade parts and now I have everything I need to make a vector test bench.

Stage 1: prep the power supply

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Atari vector power brick

Early Atari vector games required a series of different AC and DC voltages so Atari created a beefy power supply which is now fondly known as a vector power brick. They’re usually pretty rusty, have a number of blown fuses and one dilapidated large capacitor (known as a Big Blue). My brick has had all the rust removed, been primed and sprayed, had all 3 x 3A and 3 x 7A fuses replaced and the Big Blue swapped for a modern replacement. I took the time to replace all the spade connectors, fitted a cherry door switch and replaced the dated power cable. A quick follow along with a YouTube tutorial and I was happy the voltages were correct.

Part 2 should show me testing the AR2 (Audio Regulator) PCB which further controls and maintains the vital voltages to run the main game PCB. Now if only I could find another good YouTube tutorial

Introduction

I’ll be using this blog to keep track of all my projects as there’s just far too many to keep in my head. Expect to see arcade, consoles and programming stuff turning up if and when I think about it. Hopefully keeping track of them all will encourage me to actually finish a few more.

So, no fanfare… just projects to follow.