JAMMA Video Game Test Rig Box

I decided to package up my JAMMA test rig so that I could demo Crazy Otto at Rochester BarCamp for today.  My design was basically a box that would house the entire thing, with a nice control panel for player 1.  As you can see in the above image, I have the A/V cable going to an external monitor.  Broken out on the box are player 1 and 2 start, coin 1, and player 1 controls – joystick and 3 buttons.  On the right side of the box are the three “coin box” controls — Test, Tilt, and Service, for testing those functions of the board.  Also on that side is a nice handle to help it be portable.

This is a continuation of part 1, where I updated the AV connections of the rig.

This is about the extent of blueprints I have for this.  I knew I needed 14″ depth for the monitor, and that it needed about a 2″ rise from the back to the front to put it at a good angle.  I wanted it to be 18″ wide, and 24″ deep.  That would give enough room for a game board inside of it, as well as for a decent sized control panel.

 I started by cutting a sheet of plywood I’ve had in our garage for a while.  I also built the control panel using spare parts I had.  Thanks to members of Interlock to help me use the table saw, suggest tools and offer bits of wood.  :D

Some standard microswitch buttons, and a nice ball-top leaf-switch joystick.

The basic construction is that I glued some cleats on the inside of each side. Then the back, bottom, front and control panel will be screwed to it.  After that, it looked like this:

 

I also cut and drilled a small metal bracket to hold the power supply in place, which you can see in the above.  The coin 1 button on the front has a 12v light in it.  The old P2 controller is still attached to the JAMMA rig, in case I want to test/play 2 player games.  You can also see the 1 1/4″ fine thread drywall screws holding it together here.  From here, the only change is that I painted it, stinking up our garage in the process. heh.  The top lid hooks under the control panel, and has a cleat in the back to keep it from sliding off the back.  There’s a single screw to hold it in place, and to let it be carried withot the contents falling out.

The great thing about this thing is that it’s easy to tote this thing around to play/demo games and such.  It takes two trips since the monitor is cumbersome, and the box itself is pretty heavy, but it’s SIGNIFICANTLY easier than toting around a full arcade cabinet.

For reference, here’s the JAMMA pinout standard:  (Most games since the late 1980s use this or a variant of it — for example, Neo Geo adds additional buttons on unused pins, Rampart uses a trackball on the joystick pins, and Mortal Kombat has additional buttons on another interface harness.)

The power and ground at the top portion are wired directly to the old PC power supply.  Coin counters and lockout coils are not wired to anything.  The speaker wires are broken out to a RCA plug, and the Video (RGB,Sync) are out to a DIN connector, as seen in the previous post.  Service, Tilt, and Test are wired to the three switches on the side of the box.  Coin switch 1, and the two start buttons are on the control panel, as are all of the 1P controls (on the right).

from on April 19th, 2014Comments0 Comments

How to 3D-print a Handle and Trigger for the 3Doodler (and to make it look like a Phaser).

The 3Doodler  is a hand-held 3D printer!  The company is now taking orders.  Last summer it was a “crowd-funded” Kickstarter project, and we invested in it.  Our reward for sponsoring this clever invention was to receive our very own pre-production device in January. It is kind of a cross between a hot-glue gun and a 3D printer.

Doodler 1

Unlike a glue-gun that melts a stick of rubbery plastic to glue things together, the 3Doodler can melt a 3mm filament of ABS (a kind of plastic that many things are made of) and extrudes it into a softened web-like thread that can draw up off of the paper in the open air and into almost any shape you can imagine.  While it is intended to be used for making plastic objects by drawing 3-dimensional doodles, we use it primarily to fix plastic objects that have broken or to hack plastic things by adding features to them.  But more about that in a later blog post.

Now we would like to tell you how the team of MacGyvrBot and Skip have found a way to make this great product even better!

Doodler 2

We used Tinkercad to hack-up a model for a Handle and Trigger mechanism, and then we published the design on Thingiverse so that anyone with access to a 3D printer can download the .stl files and make a Phaser Handle for 3Doodler of their own.

or you can just click these links to download the 3 files

Handle

Trigger

Plug

This kind of sharing is called open-source hardware design and the practice allows people to build on each other’s ideas.  You can also use Tinkercad to copy this design and modify it with your own ideas.  Progress is faster this way, so open-source design is the best way to get the most out of 3D printing.

Doodler 3

This Phaser Handle makes the 3Doodler look cool (like the Star Trek weapon), but it also makes doodling more comfortable (especially for people with small hands).  The makers of the 3Doodler obviously have plans for making a handle, because they provided a handy mounting bracket with threaded holes for M3 screws.  But we couldn’t wait!

The handle alone is beneficial, but using the trigger with the handle keeps the hand more relaxed during extended doodling.

Doodler 4

The Phaser Handle is attached to the 3Doodler with a pair of M3 x 10mm screws (any head design).  The trigger attaches to the handle with a pair of small flat head screws (such as 6-32 x 3/8 inch or M3 x 6mm) serving as hinge pins.  The screws are available at Lowes and Home Depot.

Doodler 5

The handle is hollow to allow access to a mounting screw (rather than having an infill of plastic in a sparse honeycomb pattern).  If your printer drops a few threads while bridging across the top of the handle, just let it finish the job.  Chances are it will recover before the top layer is reached.  If it fails, you may have to adjust your slicer settings (such as slowing the speed for bridges) and try again.

In our next blog post, we will show you how to use the 3Doodler itself to update the Phaser Handle.   The exercise will be a good demonstration of using the 3Doodler to hack an existing product.

Stay tuned!

from on March 10th, 2014Comments0 Comments

Repairing the audio on a Pac-Man arcade board

I got this knockoff JAMMA Ms Pac-Man arcade board many years back.  It’s got two ROMs instead of the authentic board’s 6 (9 for Ms Pac), and is substantially smaller than the “real thing”.  The only issue is that the audio is poor… REALLY poor.  It makes sounds but they’re… wrong and noisy.

I took over some desk space at Interlock and got to work.  (I should note that the beverages you can see here are other people’s, not mine. ;)

I traced the audio circuit on a real Pac-Man schematic (seen on my laptop’s monitor), and buzzed it out on the Yenox board to try to corrolate the two.

I had to trace four similar paths from a quad flip-flop, through a quad bidirecional switch, to the audio output.  It got really confusing at times, and took me probably a bit longer than it should have.  For the most part, they were pin-for-pin correct as far as how they were wired.  These chips have the same device (eg, a flip flop, or a logic gate) repeated 4 or 6 times.  In some cases here, the Yenox board had a different one of these devices hooked up, which added to the confusion.

This portion of the circuit uses 8 resistors to make a digital-to-analog converter. These generally work by having different resistance levels, usually something like multiples of eachother, eg,  10k ohm, 22k ohm, 47k ohm then 100kohm.  I traced out all of the lines on the Yenox board and I found out that not only were the resistors in the wrong order on the board, but they were also wildly wrong (47 ohm instead of 4.7k ohm), which you can see in this table I made:

 

You can see these resistors here on the Yenox board, right next to the JAMMA connector.  They start from the left with R1 (my notation.)  The printing on the board completely matched the resistance values that sat on them, so it’s obvious that the engineer who made this board seriously screwed it up in the design stage.

I replaced resistors R3 – R7.  I put them in with the gold band closer to the JAMMA connector, rather than the other way around.

And now it sounds near-perfect.  There’s a little bit of popping left, but I was getting tired and decided to head home for the night.  I’ll hook it up to an oscilloscope at some point and see if i can figure out which line is causing problems.

For what it’s worth, I also did the same as this on the video path DAC, seen in the above picture as the next three groups of resistors.  In the above, the group of four and then the group of five are for audio, then the next group of three is for the “red”, next three for “green”, next two for “blue”, and the remaining two are for the sync.  Again, there were some 47 ohm resistors mixed in, and notice two of the three in the “green” section are identical (red-red-brown)… which is surely wrong.  Color is now perfect on the board too!

from on February 12th, 2014Comments0 Comments