For over 20 years I've been playing, collecting and restoring pinball machines, and having gone through almost 300 machines in that time, I finally needed to venture into building my own games from scratch. But like learning to walk before you run, I decided to start with doing a re-theme of an old EM game with score reels and chimes, but more importantly no complex video or music to worry about.
Since Gottlieb mostly did "safe" themes like bowling or cowboys, I thought I'd try to create something a little more "racy" - a general "Hot Rod" theme based on drag racing, set in the late 1970's, the pinnacle of EM pinball supremacy.
To that end, our journey begins with an existing machine that we'll be re-theming, since starting with a base game is much easier and cheaper than building things like cabinets from scratch and collecting all the various little parts and pieces. In this case, my base game is "Mustang", an unremarkable 2-player game from 1977 that I picked up from a friend for a few hundred dollars in "as-is" but decent condition.
Being a 2-player game was perfect for the drag racing theme - a head-to-head competition between two drivers - and the game in question is not rare or highly sought after, so "destroying" it to bring my vision to life wouldn't upset people too badly and my plan was to make it far better than it ever was in its first life.
Not many features on this machine - not even powered slingshots! Turning this game from a snoozefest into a modern game with modern features like multiball was going to be a challenge.
Inside the head. Here you can see the eight score reels (four per player) plus the match stepper and associated logic, plus the Jones connectors at the bottom. Can't tell you how many times I've picked up a game where they've cut the wires not realizing the head comes off!
Under the playfield you find more steppers and relay banks to control feature lamps, drop targets and other playfield devices. All said, the game was in very nice original condition, a bit worn around the edges but it wouldn't have taken much to get playing as-is.
Taking the head board out of the game, I removed all the stuff that won't be needed for our conversion to modern electronic controls. Not much left - the eight score reels and the credit stepper.
Same was done to the playfield - all relay logic removed and only lamps and devices that interact with the ball are left behind. Without the support relay logic, the bare-bones nature of the game is more evident by the sparse number of coil-driven devices compared to other games.
The pile of coils, switch banks and steppers left over after ripping out all the old EM logic from the head, playfield and main cabinet. Don't worry, none of this was tossed out - it goes off to the parts bin to be used to save other classic EM games. It weighs a ton!
Originally, the plan was to make my own control boards. In this photo is a switch matrix, a solenoid board managed by an Arduino, a flipper board that handles direct fire, and two rectifier boards to convert the AC voltage from the original transformer to DC for use with modern electronics.
Some initial tests doing a lamp matrix using existing pinball designs showed promise but I kept running into programming issues on the Arduino - with the overhead from the libraries to make programming them simple, I wasn't getting accurate enough timing, and lamps would flicker badly. Ultimately I am not a very good programmer and this kind of embedded development was beyond my abilities.
This is when I discovered the Open Pinball Project - a very low cost open source pinball controller system based on the Cypress 4200 PSoC family of processors. Using very inexpensive dev boards - less than $4 each - you can control coils, lamps and switches using a serial API over USB.
There are a number of more commercial options available, but given the budget involved with this game they didn't make financial sense at the time, whereas the complete set of boards pictured above totalled less than $100 fully populated.
Mocking up where the controller boards would sit. Having them on the playfield, closer to the devices and lamps they were meant to control, would mean less wiring and ultimately less expense.
At the top is lamps and bottom coils. The lamps are controlled by BS170 MOSFETs while the coils are IRL540Ns.
Initial wiring up of the lamps. The positive lead for the lamp voltage is attached to the lamps, while the wire returning to the board connects it to ground, allowing current to flow and the lamp to glow. All lamps are direct drive - no lamp matrix to worry about.
There's no photo but the coil and switch wiring was run after this, as well as wiring in the head and cabinet.
For the head, boards are wired up on a test panel and connected to the score reels. Each score reel has four connections - advance coil power and ground, and zero position switch signal and ground, all wired with modern Molex connectors for easy swap outs.
Score reels work similar to how a slot machine reel works - it advances a space (showing 0-9) with each firing of the coil, and a switch is depressed when the reel is on the zero position.
The brain of the game is a Raspberry Pi 3. In this photo are three controller boards to handle coils, lamps and switches, the RPi3 and a newer version of the rectifier board which handles lamp voltage (6.3VDC) and coil voltage (24VDC) while a separate switching power supply in the body handles 5VDC for game logic.
In order to keep track of the wiring for later troubleshooting as well as for programming the game, careful documentation of wiring colours, which controller, wing and pin it connects to, and the function it performs is maintained in a spreadsheet.
It's a good thing these boards are cheap - I managed to fry a bunch of them while trying to figure out the power wiring and common ground. Whatever you do, don't leave a floating ground, tie all grounds together near the power supplies!
For programming the game logic I turned to Mission Pinball Framework, an open source project that is designed to make constructing a working pinball machine as easy as possible for those of us who are not as versed in programming. It supports a wide variety of controller hardware (including OPP) and handles all the low-level logic of stuff like direct fire coils, switch handling, coil pulse timing, lighting and so on. In addition, it also handles gameplay functions like score and player tracking, defining "ball devices" and setting up game rules.
It does this primarily via a YAML-based configuration system as displayed above - this defines the "base" mode where a game would spend most of its time and lets you set values for scoring, creating counters to handle how events are tracked and so on.
Broken down into its simplest definition, a pinball game is a "state machine", meaning that gameplay is made up of events that change the state of different values, triggering more events and so on until you run out of balls. In an EM like Hot Rod was originally, that state machine is very simple and might only have a few logic accumulators - for example "complete rollovers to light Extra Ball". However, thanks to the power of modern electronics, that game logic can be greatly expanded. MPF does most of the heavy lifting for you, leaving you free to concentrate on the more fun aspects of pinball making - the rules.
For functions that the MPF YAML configs can't properly handle, you have the option of writing your own modes directly in Python. In this example, to properly emulate the bonus count EM-style where each bonus light is awarded one at a time, a script follows that logic flow.
Although I had limited experience in Python it wasn't too hard to use online tutorials and examples to muddle my way through the basic logic for the bonus count and some other functions. If I can do it, anyone can.
The above is the console window of MPF while the game is running and the start button has been pressed to begin a game. It shows a ball served into the shooter lane (far right column) waiting to be plunged into play. The green highlighted switches are "active" - the large block on the left are the score reel zero position switches (ie. scores are at zero) and in the middle column it shows two balls in the trough and one in the shooter lane.
The far left column shows the active game modes. When most players think of modes in pinball, they think of ones they've started while playing, but in MPF modes can be any "state" that's active - so for Hot Rod, there's the "base" mode, a special handler for the H-O-T rollover lanes, "gi" handles the general illumination, and so on. Modes will start and stop as the game progresses.
The console allows you to see game state at a glance while designing your game software, or while playing, to make sure everything is working as expected. The console is separate from any display your game might have - most modern games will have score displays and/or a screen the player can see for animations or game info.
Since this is an EM, the only output devices I have are score reels, lights and chimes, which actually makes programming the game a lot simpler in many ways but much harder in others - I don't have to draw fancy graphics, but also communicating with the player is extremely limited. For example, on a modern game if a player loses a ball quickly it will often return the ball to a player (ball save) and display on the screen a message saying "Ball Saved". On my game, I return the ball and ring a bell in the backbox that isn't normally heard during game play as "feedback".
Mustang was a single ball game, but Hot Rod was going to be a modern version of the classic EM, and that meant Multiball. That also meant the one-ball trough needed to go to make room for one that could handle three balls. Originally I got it working with the single ball trough but it was time to upgrade.
Here I've removed the apron and I'm taking out the metal guides from the trough.
Underneath is the existing single ball eject coil and trough switch. The original game did not have a shooter lane switch as it wasn't needed for a single ball game, but I added one which can be seen to the right side.
Everything out of the way.
Using a jigsaw, the two holes were connected by a cutout and the top of the new trough is test fitted in place. Horse does not approve.
Ball guides are added to direct balls to the new trough, and the bottom part is also installed.
Well this is a problem - the new trough extends down and hits the chime box!
Chime box is moved further into the cabinet out of the way. Here you can see the bottom part of the trough - balls roll to the end and come to rest, where the upward facing coil can shoot them up and out when it's time to serve a ball. This trough is designed to hold six balls but I'm only using three.
The apron tray was modified to make room for the trough, and you can see the red opto glow from the trough which are used to detect the last ball and any jammed balls. Definitely nothing like this in 1977.
Mustang also did not come with powered slingshots, which is a travesty, so I decided to add them myself. This is the underside of the slings, showing a single switch in the middle and two lamps.
Switches and lamps removed, there's room to expand the three holes to make space for two switches and the slingshot arm and coil.
Marking where to cut on top.
Holes expanded, slingshot hardware installed.
It's a tight fit but it's all in. I used Williams sling mechs for this because I had them sitting around - just pretend they're Gottlieb.
Working powered slingshots! They make the game much more exciting and should never have been left out of the original.
At this point, the game is physically working 100% with all lamps and coils including the score reels, so the next step is to start the visual transformation.
40 years of cokes and who knows what else was put through this coin door, so I did a full restore on it. This is the after photo.
Measuring the original backglass for score reel window dimensions to use in the new artwork being designed.
The top of the playfield is completely striped down to the wood, but leaving the wiring and mechs installed underneath, a decision I would later regret.
This image gave a few of my EM-loving friends a reason to gasp as I sanded the relatively decent original artwork completely down to the wood. This has two benefits - it gives a much flatter surface to work with and also removes any ball trails that indicate wear and tear. It's going to look brand new.
All done. You may notice some sun damage on the shooter lane, but that colour difference won't be visible on the finished game so I wasn't concerned about being overly aggressive with the sanding to remove it as it goes fairly deep.
With all the artwork gone and the playfield nice and flat, it was a good time to measure and trace all the inserts and holes to help guide the art redesign.
The original cabinet isn't exactly fine art - blocky two-colour stencils convey a vague "cowboy" feeling but that poor guy has a foot for a hand and no head!
With the side rails removed, the colour difference in the paint is obvious - years of living in smokey bars and arcades take their toll. Fortunately there's a spray can white that closely matches the original called "Heirloom White". I will also reproduce the speckle pattern as well.
Using paint stripper, the lead-based original paint just sloughs right off the cabinet. Using paint stripper instead of sanding cuts down on the amount of airborne lead from the paint and is much safer overall, but a lot more work and very messy.
With the paint gone, the deep gouges in the side are more visible, as are a few love notes. These will all be fixed with bondo and fibreglass.
Back in the day, the only way for people to know about your pinball glory was to take a pen knife to the head and carve your high score for all to see. I wonder if Paul Rizzo got in trouble for vandalizing this poor game.
Any splits in the plywood or cracks in the joints were filled with wood glue and clamped tight, then after drying sanded smooth.
Using fibreglass on the corners and bondo in the middle, the sides are smoothed out nice and flat and all evidence of the gouging and hearts is gone.
The front of the cabinet was particularly chewed up on this game so it was reinforced with fibreglass resin and sanded into shape.
After glue, bondo and fibreglass, the head is primed and ready for paint.
Same with the body. The different colours are regular primer and a high-fill poly primer that helps to fill in the woodgrain. Everything is rattle-can, I don't have a compressor that can handle painting. Also I needed to trim those weeds.
Proper surface prep is critical! There was some contaminants here that caused the paint to crackle. The only solution was to sand the whole front down, clean with naphtha, re-apply the primer and repaint. A costly mistake.
After the white is dry, the speckle pattern was applied by dipping a toothbrush in a bit of black paint and using a thumb to "flick" the paint at the surface. That isn't the factory technique but it's surprisingly effective.
The speckles were done at the factory to help hide any flaws in the cabinet plywood and minimize any visible damage over time. Although it was commercial equipment, they weren't really built to last more than five years and as such they took a few shortcuts to save money like using cheaper wood.
Ironically, this "throwaway" game from 1977 managed to survive 40 years and is more solidly built than any pinball machine made today, using mechanisms with much thicker metal and overall better construction. Made in the USA!
As part of the redesign, I moved the score reels from a stacked configuration to a side-by-side one, more like the drag race style the game's theme references. Using the measurements I took earlier, I mapped out the location for the score reels and credit stepper on a new plywood sheet - you also get a preview of the new backglass art.
Holes rough cut with a jigsaw.
Test fit of the score reels.
With the cut guide removed after drilling for the lamps, the final backbox panel is ready to be wired.
Flipping the board over, the RPi3 is located above the match lamps, while all the control boards are placed between the score reels. After wiring the lamps, the rectifier board will go opposite the credit stepper.
The backbox board is test-fitted in the head and fits perfectly. The backglass sits in front of the board and the board itself tilts back to allow access to change lamps.
From the back, with the rectifier board installed. Here you can see the metal "hinge" brackets, the hold arm at the top and the stop bracket on the right. All the metal bits have been cleaned and polished.
With the base paint complete and the head rewired properly, it's time to paint the stencils. Originally, they used thick steel templates to paint the graphics, which helped mass production but had very low detail and tended to have a lot of underspray. Although this is a tribute game, I wanted to do better than factory, so I picked up a stencil cutter.
The USCutter SC-Series is a low-cost unit that provides quite a lot of features for the money and is also Mac-compatible so you don't need weird Windows drivers to use it.
Here I was calibrating the speed and cut pressure using the built-in test cut. Ready to go.
The first stencil is cut and the masking weeded out where colour should go. The first colour will be red, and this is the side of the head. The material is Oracal 812 stencil mask which has decent adhesion without pulling paint and allows for very detailed stencils.
Stencil applied. The masking tape fixes a couple of tears from my inexperience in repositioning while applying the stencil. Ready for paint.
First pass with red, which is fairly transparent. Several light coats get the job done.
Repeat with black.
The finished stencil. Original games used two colours, and although it's tempting to add more, I wanted the game to look the part on casual inspection. That said, the amount of detail and the crispness of the lines will tell any experienced pinballer that this isn't original.
Additional stencils added to the front.
When cutting the head stencils, I noticed that they came out a tiny bit bigger than I expected, I printed out the side stencils on tracing paper using the pen option on the cutter so I could check the size and placement prior to committing a lot of expensive stencil material.
Turns out that was the right decision, as the registration marks were a couple of inches off the side! I found a calibration setting in the cutting software and adjusted it to the correct sizing.
As before, red first.
The right side cabinet red complete.
Left side cabinet red.
Left complete. Those with sharp eyes may notice that left and right are different stencils - each car is in the foreground on their respective sides. Another thing the factory never did but I think is a nice touch.
With the black complete, you can see our drag racers - a '55 Chevy and a Corvette.
Ahh yes, the dreaded checking. No issues with the white, but the red seemed particularly sensitive to this problem. What this meant was a complete sanding back down to bare wood, repainting the white, redoing the speckling, then redoing the red. A couple of days were lost to this.
After the stenciling was complete, the cabinet was clearcoated with a satin finish to better match the original finish but also minimize the stencil edges and give a nice, smooth surface.
What's this mystery package?
It's the new backglass illustrated in the style of Gordon Morison, the original artist who did a large number of the original games for Gottlieb in the 70's and 80's. The illustration is by Jason Goad, who did an excellent job re-creating the 70's look to make the game seem of the era.
Older games used a blackout layer so they could provide status info to the player, which you can see in reverse here. Number of players, ball in play, tilt and match.
The backglass is installed in the head to test the fit and that the backboard doesn't press too tightly against it when closed.
Using a handheld service light behind the glass, you can see some of the backlit info lights.
Tackling the cabinet wiring. When originally getting the game working, I skipped this step and just wired the flipper switches directly, because for that phase I didn't need coin switches or tilt, but now with the cabinet complete it was time to wire it all up. The front of the cabinet is more complicated than you might imagine as there are a number of powered or sensing devices at the front of the game - tilt bob, roll tilt, two coin switches, the start button, two flipper buttons, three chimes and a knocker.
The cabinet is partially re-assembled with a freshly restored coin door, new legs and polished lockdown bar, ready for the playfield.
Gluing the backbox board with the light blocking layer. About 1/2" in depth, this prevents the light from one lamp leaking over to light another lamp's section, just like how the original backbox board worked except that I'm using MDF here instead of particle board. So as the info lights are mostly around the edges, the surrounds go around the bottom and top left, with a small one for the tilt lamp.
Painted white to maximize light dispersal.
While that dries, the cabinet re-assembly continues with the newly rebuilt and polished chime box. All existing wiring was removed, so everything is re-wired with more modern vinyl-wrapped wire instead of the fabric-wrapped wire it came with originally. Also, molex connectors are added to each distinct device for ease of maintenance.
All the polished bits and bobs. This photo really illustrates the quality of the original Gottlieb parts from 1977 - thick metal bracket for the knocker, solid metal backing on the flipper switch, thick metal lockbar receiver, multi-ply cabinet-grade plywood for the cabinet including full-length wood gussets for the corners. All this for a game meant to be used and thrown away in only a few years!
With the cabinet work complete, it was time to start work on the playfield redesign. To maintain the vintage look, I added various hot rod elements while still retaining some of the original layout. Extra Ball lamps become Jackpot lamps, the saucers become ball locks, and text about the skill shot is added at top. Instead of horses we get horsepower!
Originally playfields were screenprinted by hand, which would be the ideal method as it has the highest detail and accuracy, but I lack the facilities to properly screenprint a piece of this size, so instead I used stencils and an airbrush.
This is for the base white layer, which takes up most of the playfield.
First pass with the airbrush. You'll note the patchy appearance - it ended up taking about four coats to get a consistent white layer down. This is my first time using the airbrush so it's a learning process of how to get good results.
White layer complete.
Like with screenprinting, colours go down from light to dark. This is the yellow layer.
Why is the stencil all cut up you ask? Well, it turns out those measurements I took earlier, combined with the inaccurate scaling of the cutter, resulted in the artwork being slightly off in a number of places - enough so I had to make on-the-fly adjustments to re-position parts. In the end it worked out okay but only because the art was relatively simple and abstract - if it had been detailed at all, I'd have been screwed.
Measure twice, cut once.
I didn't record the orange layer but here's yellow and orange complete. The shapes are starting to be more recognizable.
Red. Flames! And some words!
There were a few screw ups as I went along that needed fixing. Here I redid some of the white after the red was positioned incorrectly. You'll also note the underbleed in the orange, which was due to not properly applying the stencil and being too aggressive with the airbrush. Fortunately the black keyline will cover that up. I learned a ton about airbrushing with each colour I put down.
More examples of the repositioning needed to get stuff to line up properly. It was only a few millimetres off but it was enough.
Hot pink! The one advantage airbrushing has over doing a digital print is that you can do some wild colours.
A closeup of the airbrush area. Multiple light coats to avoid buildup.