The Black Knight Rises - June 2022 Progress Update

A lot has happened since the last full project update.  The Black Knight Rises playfield build is completed, the electronics are all working, the cabinet switches were wired up, the playfield finally left the rotisserie and lives in the cabinet, and gameplay debug and multi-media development are under way.

The Black Knight Rises has risen!

When time has allowed, over the past 8 months I have troubleshot some build issues, swapped out some mechanical assemblies and switches, refined controller firmware, and did a ton of code development.

Except for a few small items, the physical build is essentially complete.  The main task that remains for me to complete is the actual game multi-media elements like sound effects, videos cut scenes, DMD animations, plus some enhanced game rules.

Click through for the full update.  There were a lot of lessons learned.

The Challenges of 3D Printed Pinball Parts

Life for parts inside a pinball machine is rough.  Literally.  Anything that comes into contact with a speeding ball of steel is in for some abuse.  Look at some of the metal components that have been in service for decades, and they will often be deformed or broken.  And even more destructive are the super powerful solenoids.

This makes life incredibly tough for 3D printed plastic pinball parts.  Is survival even an option?

Most of the 3D printed parts I've designed do not come under any direct stress.  Things like electrical connection mounting brackets, or decorative toys.

For example, here is a 3D printed Monty Python Black Knight toy on top of the upper playfield's shooter lane ball ramp.  I was finding that balls would bounce and get caught on the metal hood.  A 3D printed flat-topped cover solved that problem, and provided a perfect place to mount a toy.

A 3D printed cover (black) prevents balls from getting stuck, and made a perfect spot to mount a toy

But one of the 3D printed parts I designed for The Black Knight Rises are some drop  targets, to make an Alvin G drop target assembly cosmetically match the Williams drop target style.

Designing a drop target doppelgänger was easy.  Coming up with a design that would survive has been the real challenge.

My original prints were in ABS.  They broke.

I also tried PLA, which broke even faster.

I upgraded to PETG, which lasted longer, but also broke.

I modified the design to be more massive, in hopes of making it more robust.  And that broke even faster.

Original Alvin G drop target in white.  ABS red and PETG black design revisions all broke.

Surprisingly, the target head itself never broke, even though it takes direct hits from the pinballs.

Click through to learn the rest of the story.

Chameleon Power Driver v5 - It Works!

 This update should have been posted last October, but I got sidetracked.  Better late than never, eh?

My PCB order from JLCPCB arrived on October 1st, and luckily all boards looked perfect.  For this order, I had the PCB's panelized, so I could assemble them on my Pick'n'Place machine in batches of six.

The Chameleon Power Driver v5 PCB's waiting for assembly

I made a pretty cool video showing the PCB assembly and validation process - it's a surprising amount of work:  Chameleon Power Driver v5 Assembly

At the end of the video you can see a brief glimpse of my new testing jig.  I custom designed and 3D printed this jig to test each power driver.  There are spring loaded POGO pins inside that make contact with various test points on the PCB.  

Click through for the rest of the details.

Progress Update & Troubleshooting Power Driver Issues

I originally wrote this update back in September 2021, but I got sidetracked and it never got posted.  I'm posting it now, as a precursor to the follow-up posts that are coming soon.

Chameleon Pinball Engine Software Updates

Chameleon Pinball Engine software updates were more extensive than I expected, as I was in the middle of a massive rewrite 4 years ago when I took a break from the project.  It has taken a lot of effort to figure out what changes still had to be made.

This has actual been a source of disappointment for me.  In my head, I was remembering being much further along in my coding.  I had certainly brainstormed a lot of features, and even begun coding a few of them, but upon code examination I'm finding little of it complete.

A lot of the missing functionality has been in the playfield configuration section, which means I have to write new code to handle all the new features I've been planning for years.

The good news is that I've improved my coding skills over the past five years, and I'm a much better programmer than when I started the Chameleon Pinball Engine all those years ago.  The new features are coming along quite easily.

Another Chameleon Power Driver Flaw

Four years ago, in my runup to the 2017 Southern-Fried Gaming Expo, I was testing my Chameleon Power Driver v4.0 with a Magna-save electro-magnet, and it was working fantastically... until it wasn't.  I thought my new design was immune to Transient Voltage Spikes (TVS), as if somehow the laws of physics ceased to apply to my design.  Physics proved me wrong, and the power driver was easily fried when hundreds of volts rushed in from the collapsing magnetic field.

Click through for the rest of the story.

The Black Knight Rises - Progress Update

These past two weeks have been very productive, and I am getting closer and closer to firing up the solenoids.  There's so much to talk about.

In this post I cover my new 5v LED power supply (tweaked to 5.5v), measuring the Chameleon IO Controller's power consumption, updates to the ChameleonIOController.dll, a custom 3D printed wire connector bracket, wiring up main power and ground to the power drivers, a potential ChameLED v2 redesign, playing around with the IO controller's latency now that it's hooked up to the playfield, and beginning the Chameleon Pinball Engine's software updates.

Yeah, that's a lot to cover, so be sure to click through to read the whole post.

5.5v LED Power Supply
I picked up a new 5v 5A industrial power supply to handle the LED's.  With it hooked up to my voltage meter, I trimmed the potentiometer to set the output voltage to 5.5v, splitting the difference between my ChameLED's and the CoinTaker LED's voltage designs.

Powering up the LED's with this new power supply, the difference was night and day (or more like night turned into day, that's a lot of light!).  The 6.3v CoinTakers now look fantastic, nice and bright and with almost no flicker at all when PWM dimmed.  And of course the ChameLED's are still bright and beautiful with absolutely no flicker!  I'm not really sure why the CoinTakers has a minor bit of flicker, but I expect it is due to their fully-rectified AC/DC design, though it could be because I'm still slightly underpowering them.

I put my ammeter on the new power supply with all 76 LED's lit up, and I recorded 4.4A, so it's safely within the 5A capacity of this tiny power supply.  Looks like I got a winner.  This also means that, on average, I'm now pulling about 58mA per LED, though I haven't yet retested the ChameLED vs. the CoinTaker to see how each performs.

The Black Knight Rises - First Light

The Black Knight playfield, lit up for the first time with the Chameleon IO Controller and ChameLEDs

Assembling a new Chameleon IO Controller board

Over the weekend I assembled another Chameleon IO Controller board, and it came out much better.

For this attempt, I upgraded my Reflow Toaster Oven with two additional 320w heating elements that I scavenged from a spare oven, bumping output from 1500 watts to 2140 watts, and this greatly improved the oven's ability to follow the solder paste reflow profile.  Of course this meant it was now too powerful for a normal household 120v 15A circuit, and I've only got a single 20A outlet in the entire house.  Luckily it's in the perfect spot in the garage right next to the garage door, which I can open for fresh air during reflowing.

I also installed my 3D printed linear clamps on the stencil printer, which greatly improved solder paste alignment, preventing movement during swiping.  

I switched to some fresh solder paste, ChipQuik's Smooth Flow, and wow did it flow smoothly!  The deposited paste looked much thicker compared to my previous attempt which had sparse amounts of paste in a few spots.  I was actually worried it might be too thick, even though I only made a single swipe.  

Semi-pro stenciling tip: do NOT make multiple swipes, as with each swipe you force extra solder paste through the stencil and it builds up and leaks under the stencil, causing shorts during reflow. I made this mistake often in the beginning. Automated stenciling machines make a single quick swipe only, and you should replicate this method if doing it manually.  You have to trust the process, it works.

One additional tweak I made was simply working faster.  The last board I assembled took over 4 hours from stenciling paste to reflowing the board, and the solder paste I'm using only has a 4-hour working window.  This time I went from stenciling paste to reflowing in under 1 hour!  

Those 4 changes addressed the biggest issues I noted from my previous attempt, and they definitely helped a ton.

Unfortunately, a new issue cropped up.  Read on to learn more and see the First Light Video!

Chameleon IO Controller - Adventures in Latency Testing

Chameleon IO Controller & Round-Trip Latency

One of my primary objectives when designing the Chameleon IO Controller was minimizing round-trip latency.  In mechanical games like pinball, lower latency improves game feel, by reducing the amount of time from pressing a cabinet button to a solenoid firing.  If latency is too great, you will notice a lag after pressing the button until the flipper fires, or after a ball hits a slingshot and the slingshot activates.

Unlike a typical pinball controller where the switch to fire a solenoid (i.e. a flipper) is directly connected to the solenoid, my design takes the button press and sends it over USB to the host PC, where my Chameleon Pinball Engine software processes the button press, and sends a command signal back over USB to turn on the solenoid.  

As the Chameleon IO Controller has both the gamepad buttons and LED outputs all on a single PCB, effectively the signal makes a round-trip from IO Controller to host PC and back to the IO Controller.

This design introduces latency at several distinct points.  There is the latency in the IO Controller to detect a button press and send the new button state info to the host PC.  There is latency in my pinball software to recognize and process the button press.  There is the latency in sending the new LED state back to the IO Controller.  And finally there is latency in the IO Controller to actually turn on the output.

My previous post detailed working on the Chameleon IO Controller's firmware to improve PWM performance, so of those four distinct points affected by latency, I've already addressed the last two.  My goal with this new round of testing is to work on the other two points.

Below a certain threshold, latency isn't an actual problem.  When you're playing video games, as long as latency from button pressed to pixels updating stays below 40ms, response feels instantaneous and you'll have a great experience.  But real world games like pinball are more demanding - physics waits for no-one - so latency needs to be even lower for good ball control.

Modern Firepower - Upgrades and a Tune-up

It's been about 4 years since Modern Firepower received any attention under the hood, and it has been such a solid build it really didn't need any attention.  I had a switch wire break a solder connection once - my own fault for keeping the wires taut between connections, always leave wire slack - but beyond that it has been pretty much trouble-free.

Well, except for that one sheared pop-bumper bolt I discovered in the cabinet a few months back, still clinging to the nut it liberated in its desperate attempt to escape a life of pinball attacks.  It crossed my mind that perhaps I should see where the destroyed bolt was located, but since Williams style pop bumpers are connected with three bolts, I didn't give it too much thought.  From the top side of the playfield, all four pop bumpers seemed solid.

Fast forward to the end of the 2017 Southern Fried Gaming Expo.  While packing up Modern Firepower for the short trip home, I noticed another sheared pop bumper bolt lying underneath it on the floor.  Though I couldn't rule out its origination coming from a nearby machine, in my gut I knew Modern Firepower was the source.

Modern Firepower at the 2017 Southern Fried Gaming Expo, next to an original classic Firepower - photo by Juan Josino

Read on to see the Modern Firepower repairs, tune-ups, and the very special upgrade I installed...

"The Black Knight Rises" - Week 5 Progress

Though The Black Knight Rises missed the show, the work must go on...

Days 29 & 30 - Saturday & Sunday at the 2017 SFGE:
For me, one of the best things about attending the Southern-Fried Gaming Expo is hands-on time with hundreds of machines, including some custom machines.  Sure, I was having fun playing, but this was also work, research to be specific.

As I would play each game, I would make note of any unique features, not just from a playfield design standpoint, but more importantly from a software capabilities standpoint.

For example, I got to play American Pinball's freshly assembled Houdini.  At one point during gameplay, I triggered a mirrored and reversed flipper mode, in which the right button controlled the left flipper, and vice-versa, plus the flipper bats stayed in the upright position, and you had to press the buttons to lower them, releasing to hit the ball.

With a few lines of code, I could certainly add such a routine to the Chameleon Pinball Engine.

It was also a treat to see under the hood of Scott Danesi's most excellent Total Nuclear Annihilation custom pinball machine.  I learned some simple things, like how a drop target can be both raised and lowered by adding a second solenoid to "hit" the target and make it drop, and that there is a stock Williams flapper style one-way ball gate that includes a solenoid to raise the gate, opening a passageway to both directions of travel.  Scott also has developed his own Computer Startup and Shutdown Controller, allowing the standard power switch on the bottom of a cabinet to directly, and safely, power cycle a PC.

I came home with a mind overflowing with ideas, and it will take a while to work through them.

Read on for the rest of this week's progress...

"The Black Knight Rises" - Week 4 Progress

With less than a week remaining until the 4th annual Southern Fried Gameroom Expo, I was now in overdrive working 16+ hour days.  The lack of sleep was beginning to take a toll on my ability to work.  I began to notice that even small obstacles would completely derail progress as I struggled to think through solutions.  I'm beginning to regret the challenging 4 week timeline.

Still, I pushed forward.  This post is longer than most, as a lot happened this week.


Day 22 - Saturday:
The cabinet felt very close to completion, and I was determined to spend half a day and knock it out.  I had applied the Danish Oil on Monday, and after giving it over 4 days to cure, it was time to apply a polyurethane protective coat.

But first I wanted to finish the trim out.  During parts sourcing, I had stumbled onto reproduction Black Knight cabinet side rails, with the dual flipper/Magna-Save button cut-outs.  Of course, being sized for an 80's style cabinet in which the side rails extend to the very back of the cabinet, they were too long for a modern standard sized cabinet with a pivoting backbox.  To make them work, they would have to be trimmed to length.  I also needed to shorten the backbox hinges.

I put a ferrous metal blade on my compound miter saw and got to work.  The hinges were stamped from thick gauge stainless steel, and cut like butter.  The siderails, while much thicker than modern siderails, were still thin and soft, and more than a couple times I slipped with the saw and bent the rails.  I thought for sure I had damaged them beyond repair, but luckily with a bit of straightening and a more meticulous cutting process, I was able to get them finished.

Cutting the 1980's era Black Knight side rails to make them fit on modern cabinet.

Working again on the cabinet, I aligned and drilled the holes for the backbox hinges.  I also had to notch the side rails for the hinge bolts, and the rails were too tall.  I then assembled and tested the side rails and backbox hinges.  This cabinet build is similar to building a hot rod - merging old with new with unique, plus lots of custom fabrication.

Metal cutting finally done, the backbox pivots!

Read on to see how the final build week turned out...

"The Black Knight Rises" - Week 3 Progress

It felt like I was beginning to turn the corner in week 3.  With the fabrication and restoration steps complete, and reassembly underway, it seems I might just make my self imposed deadline.



Day 15 - Saturday:
With the playfield clear coat happily curing without me, I turned my attention back to the cabinet.  I measured and cut out the coin door and bottom panels, then glued it all up.

Clamps, a woodworkers best friend.  Plus heavy stuff to weigh down the bottom panel while glue sets.

Once it was assembled, I was able to then measure for the top shelf and the playfield backstop (not sure what else to call it), cut them out and glued them to the cabinet.

Read on for the day by day recap...

"The Black Knight Rises" - Week 2 Progress

Week 2 was more challenging than the first, and as some tasks took longer than anticipated, my goal of readying The Black Knight Rises for the 2017 Southern Fried Gameroom Expo begins to slip away.


Day 8 - Saturday:
Troy arrived early and we set off to sawing some wood.  Previously I had hoped to use my 3' x 6' Shapeoko 2 DIY XL CNC router to cut the cabinet.  Unfortunately, over the past half year I've had nothing but issues from my CNC, ranging from bad power supplies to sloppy belts and uncontrollable backlash.  I simply couldn't trust the CNC router for this job.

Especially since I was using expensive walnut.  No paint for this build.

Troy and I spent all day, and got the cabinet sides cut out, and the backbox sides planed and cut out.  The backbox was being fabricated from solid walnut, since the cut sides would expose plywood, and since it was about 7/8" thick, it had to be planed down to 3/4".  For the cabinet I used 3/4" walnut plywood.

Setting up the mobile woodshop in the driveway.

Read on for the day by day recap...

"The Black Knight Rises" - Week 1 Progress

While a lot was accomplished in the first week, a sense of satisfaction is not present.  The road seems long from this end of the journey.

For the  non-electrical aspect of the restoration, I've been referring to the excellent "Vid's Guide to Ultimate Playfield Restoration", written by VID1900 about 4 years ago.  This being my first playfield restoration (Modern Firepower was built new), I'm not qualified to give any tips, merely point you in the direction of the information I've been using.

https://pinside.com/pinball/forum/topic/vids-guide-to-ultimate-playfield-restoration#post-547712


Day 1 - Saturday:
Though playfield evaluation and parts ordering had begun a few days earlier, I decided to mark Saturday as Project Day 1, since this is where the hands on fun begins.

Troy came over and assisted me in the full disassembly of the playfield.  Every part was tagged and bagged (or boxed).  Plenty of pictures were taken along the way, at various stages of disassembly, to document where various parts should be reinstalled.  We took our time to make sure no mistakes were made.

During disassembly, all the wires were cut off of the lights, switches and solenoids - except for those related to the Magna-Save magnets and solenoids.  We took special care to examine the Magna-Save wiring to reverse engineer the power flow - a task made harder because the flippers had already been forcibly removed and their wires cut free, and the flippers were wired in series with the magnets.  Eventually I came to understand how they were wired from the factory.

With the playfield stripped of parts, it was then cleaned with Naptha, Novus, and Magic Erasers.  This was many hours of back breaking work.

It's a dirty, naked playfield...

Read on for the day by day recap...

Project "The Black Knight Rises" - Introduction

A few years back, around 2014, I came across a scavenged Williams Black Knight playfield for sale.  Many of the mechanical assemblies had been removed, and the wiring harnesses were cut and ruined, but the playfield itself was in okay shape, plus it had most of the hard to find game specific bits like rails, ramps, scoops, and the plastics.

This Black Knight, destined for the scrap heap, needs help.

I immediately realized that this was a perfect candidate for not just restoration, but a Pinball Chameleon upgrade, adding advanced sound, enhanced multi-ball, full DMD animations, light shows, an LCD monitor backglass, customize-able game rules, and more.  This is the Modern Firepower concept, but now applied to resurrecting a trashed playfield from the junkyard.

Black Knight also presented some new features for me to test and implement in my code.  Drop Targets, Magna-Save, a 3-ball Ball Lock, and four flippers.  Actually, my code already has partial support for these features, though a few tweaks would be necessary to tie them into the game rules.  For example, the Magna-Save would function just like a regular flipper, only the game would now have to disable and enable them as part of normal game-play, plus implement a timed limit on their use.

Parts that I would replace anyway, like the flippers, were already missing from this neglected playfield, so I wasn't paying for parts I wouldn't be able to use.  Plus, since I would completely rewire the entire board to connect it to my own electronics, a damaged wiring harness didn't matter one bit.

Trashed harnesses and missing assemblies... someone tried to murder this Black Knight.

One man's trash is this man's new pinball machine.

I was able to score the playfield for $200.

Another reason I jumped at this Black Knight is that, eons ago when I was first researching how pinball machines work, my buddy Troy scored a nearly worthless Black Knight playfield for about $50.  Though it was not salvageable, that playfield revealed many pinball secrets, from simple things like the dimensions of the wood side-rails, and how pop bumpers, flippers and kickers work.  Having tangible parts that I could inspect and measure, even if they didn't actually work, was game changing for someone who had never been exposed to pinball machines before.

Eventually I tossed that first Black Knight, but not before salvaging the ramps and plastics.

The remains of that first Black Knight playfield:  some metal ramps and rails, a spinner and siderail piece.

Various plastics from that first Black Knight.

Life then got busy, so this playfield has been kicking around for a few years, just gathering dust and generally being in the way.  Now, a mere month away from The Southern Fried Gameroom Expo 2017, I've decided to try the impossible: a playfield restoration and upgrade to the Chameleon Pinball Engine.

Read on to see how I prepped for the project...