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About three years ago I came across a great tutorial over at xbox-scene.com detailing how to modify classic controllers to work with the original Xbox console's various emulators. Below is a link to this forum post:
http://forums.xbox-s...howtopic=510168
The poster had himself been inspired by another tutorial detailing the process for a standard Genesis pad. A link to this tutorial can be found bellow.
http://www.xerxes3rd...ontrollerOnXbox
The basic idea is to take an Xbox controller and a standard VGA cable, splice the cable, wiring each of its female pins to a point on the original Xbox controller's board that corresponds to an control input: up, down, A, B, X, etc. The end of the controller would stick out of one of the memory card ports. The image below shows this, but a DB-25 connector was used, not a VGA - I'll explain that later.
The next step is take a classic controller such as a NES pad and solder the male VGA cord to the corresponding pins. You would then plug the classic controller into the Xbox controller enabling you to use it with the Xbox.
One of the first things I discovered is that modern VGA cords don't have 15 wires anymore, which left me short. The solution was to get a DB-15 cords instead. I found these really cheap at monoprice.com. Using this method, I was able to mod a bunch of controllers – Genesis, SNES, NES, Atari 2600, 7800, NES Advantage (no turbo), Sega Master System, etc.
Then I had a problem, which is the point of my post. My girlfriend got me a great Christmas gift: an Atari 5200 controller. At first I was really excited about modding this odd looking thing... then I discovered what a freakshow it was.
1 – The first analog controller. You know, analog like the N64 thumbstick, well, not exactly, since it didn't use optical tracking. I guess you could compare it better to the Saturn's 3-D controller since that used pots.
2 – Keypad. At first I thought, OK, no problem, its gotta have a common ground right? This is from the early 80s. Wrong. Its a keypad matrix. I'm still not 100% sure how these things work, but pretty much, the signal is somehow decoded in the console.
3 – Four buttons. Well, four buttons, but its actually two. Atari did this so that it was comfortable to use wether you were right or left handed.
So, ignoring the keypad matrix thing and the analog stick, lets count up how many pins:
Action Buttons – 2
Keypad – 12
Joystick – 6, since its an analog
Start, Pause, Reset -3
That's about 23 pin points, too many for the DB-15 controller. The solution was to do a similar mod, but using a DB-25 cable instead, which breaks down like this:
Controller Bridge – DB-25
01. Dark Blue ---------------------- +5
02. Exposed ------------------------ Ground 1
03. Red ----------------------------- Left Trigger (TP63)
04. Pink ---------------------------- Back (TP19)
05. Grey --------------------------- Right Trigger (TP64)
06. Brown ------------------------- Start (TP18)
07. Orange/Black ----------------- Up (TP13)
08. White -------------------------- Down (TP15)
09. Turquoise ---------------------- Left (TP16) [Darker greenish color]
10. Orange ------------------------- Right (TP17)
11. Green --------------------------- Black (TP69)
12. Yellow -------------------------- White (TP72)
13. Red/Black ---------------------- Y (TP71)
14. Black/White ------------------- X (TP70)
15. Purple -------------------------- B (TP68)
16. Black ---------------------------- A (TP67)
17. Light Blue/Black -------------- Left Thumb (TP20)
18. Dark Blue/Black -------------- Right Thumb (TP21)
19. Purple/Black ------------------- Ground 2
20. Light Blue ---------------------- Ground 3
Left Thumbstick (Viewed from the back)
Vertical Potentiometer [top to bottom]
1. Green/Black
2. Pink/Black
3. Brown/Black
Horizontal Potentiometer [left to right]
1. Grey/Black
2. Yellow/Black
3. Turquoise/Black
Now, unfortunately, this mod only allows for 22 inputs, but I want every button to work. The fix for this was to use diodes so that the reset button is a button combination: select & start.
First, here is what the inside of Xbox controller looks like. Its actually a lot less complicated than it looks. If you can solder and use a hot glue gun, its not too tough, just leave plenty of give on the wires. If they are too short, you'll inevitably pull up a trace and end up cursing about your stupidity for at least an hour.
So the pots in the 5200 controller are obviously old and definitely didn't match up to what was used in the Xbox controller. I tried an experiment (not pictured) when I wired the pot points from the 5200 to the Xbox. It worked, but the tracking was very slow. I toyed with messing with resistors to get them to match up until I realized I wasn't that smart or patient.Then I had the idea.
When the Xbox thumbstick pot's cap was removed, I could see there was a hole there which gave me the idea to replace the 5200's joystick entirely. I decided to test my theory: wire the 3 corresponding X and Y analog points to a spare Xbox controller thumbstick pot, stick in a spare dremel bit as the core, and cap it off with the 5200 joystick top.
It actually worked. Even better was that this joystick is self centering, so its actually an improvement on the original. I did have to solder a base to it using some spare parts. Then I just hot glued the whole thing into place. See below.
You'll probably look at those and say: “Hey, that joystick is too F'n high” and you'd be right. I corrected that later on by cutting it down, don't worry. Also, I used a dremel bit for the joystick base, which wasn't a great idea. It broke pretty quick. However, I found a common replacement that has been going strong for years. I took one of the screw pins from either side of the DB-25 cord, pulled it out, shaved off the plastic with sander, and it was a perfect shaft replacement for the joystick.
Then came the keypad. No way I could make that work easy. The way this mod works is by taking advantage of standard buttons which utilize a common ground. The keypad matrix doesn't work the same way. I looked at the flimsy 5200's keypad circuitboard and realized it had to go. Luckily, I found a nice, cheap keypad that has a common ground. It even fit in the controller with only a little bit of sanding:
Next up were the four side buttons, start, pause and reset. Here, I ended up keeping the flexible circuit sheet. I really didn't want to, because if I took too long soldering or used too much heat, the plastic would melt. Unfortunately, even very thin dot sized buttons didn't fit properly, so this seemed to be the best way to go. I had to clean off a portion of the of the traces with a fiberglass brush and solder the wires to these points. I lucked out again and it worked out OK:
Here are those diodes for the extra button:
Here are some more pictures of the finish:
And thats it, here it is all together:
So you may be thinking: “Man, thats a lot of work for just a 5200 controller.” You'd be right, but I was also able to mod a Colecovision controller and an N64. I replaced its thumbstick in a similar fashion, but used a spare Gamecube's thumbstick cap since it looked more appropriate.
Let me know if you have questions.
Edited by philexile, Mon Jan 23, 2012 5:32 PM.
