SUCCESS!!!
After basically getting to the point where I wanted to throw the original Sega encoder PCB across the front yard, I decided to go back to the initial plan of using the original mouse PCB and its optos for steering recognition. I had bailed on this original plan because it was going to require fabricating some type of bracket to mount the mouse PCB on, and when it came to that, plus the fact that I might be able to save the original encoder PCB, I chose to try saving the original PCB. Wrong choice in this specific case!
5PM EST 4/17:After I yanked the original encoder PCB, and sat looking at the Intellimouse PCB again, I remembered that I’d brought up 3 mice from my storage tub to use as potentials for this project. 2 were Intellimice, and one was an HP one. For giggles, I popped open the the HP one to see if its internals were the same as the Intellimouse, and although I recognized that a lot of the components were similar, I got to see something that I’d seen during my research readings, that I’d remembered was a nice thing to have if at all possible: this mouse’s PCB is more like one of the ones you see in various mouse hack pics where it looks like the PCB had been cut in half. When I first started with this project, and I opened up the Intellimouse, I noticed that if I went down the path of “InsaneDavid”’s project with my setup, I’d have a really tough time trying to mount this PCB in its current form against the gears for the steering wheel. I thought maybe the board I was seeing in the InsaneDavid shots had been cut somehow, but upon reviewing the one I had, the traces on the back ran the full length of the board. So, trying to cut it down would have been troublesome with someone of my skillset who doesn’t know all of the ‘magic’ regarding adding jumper wires to the traces to keep continuity blah blah blah.
However, the HP PCB is actually manufactured by Logitech (which was the PCB some recommended to be used in some of the other mouse hack articles I’d read). Looking it over, the only real difference I noticed (apart from the overall length of the PCB compared to the Intellimouse one) was that the axis wheels were different than the kind that was in the Intellimouse. I removed the Logitech PCB from the HP mouse, took one of the Intellimouse wheels, and spun it in between the optos of the Logitech mouse to see if it would register: it read the wheel perfectly! This was a great find for me, because in order for this project to work for me, I was going to have to use one of the axis wheels from the Intellimouse, rather than the HP ones. In order for the project to be a success, I needed to remove the original encoder wheel from the Sega Monaco GP control panel, replace it with an encoder wheel from one of the mice, and then mate the PCB to that. Well, the encoder wheels from the mice are plastic, and the bigger of the 2 options (the ones from the Intellimouse) is only .75” in diameter. On top of that, both types of axis wheels do not have a hole in the middle, which is what is required to mount them to the steering wheel gear of the Monaco GP control panel. I’d already been able to set one of the Intellimouse encoder wheels up for this (since I originally planned on using the Intellimouse PCB and wanted to keep apples with apples), but since this Intellimouse encoder wheel worked fine with the Logitech PCB, I already had everything I needed to make this setup work. All I had to do was fabricate a mounting bracket for the mouse PCB, and I was on my way!
6:30PMI wanted to make the mounting bracket out of plastic so I wouldn’t have any shorting issues, and I decided to make it out of an old plastic storage drawer-type thing I had lying around. The drawers were all clear plastic, and had the dimensions I needed for the bracket once I trimmed away the parts I didn’t need. Using my Dremel, I cut out an L-shaped bracked that I figured would be sturdy enough to hold the weight of the PCB, as well as be strong enough to resist the pressure from the steering gear.
7:30PMI must have test-fitted the bracket 10x, trimming and checking, trimming and checking, drilling holes to mount it to the panel, as well as drilling holes where the zip tie would go that would hold the PCB against the mounting bracket. Once I got that all squared away, next was to make sure that there wasn’t any binding between the steering wheel gear, the axis gear, and the mounting bracket. I also kept checking the movement of the mouse on the screen in Windows, to ensure I hadn’t lost any of connections or functionality during my test-fitttings.
8:30PMI loaded up my first game of Atari PP, to be played using a 32-year old Sega steering wheel, steered by a 40-yr old driver.

From my prior tests with trying to get the steering wheel to be detected, I’d jacked the analog dial sensitivity up to its max setting, which is 255%. Since I wanted to make sure everything worked, I just left that setting where it was, and started the game. As the game kicked off, I noticed immediately that the steering was working!! Only problem was, it looked like I’d had 6 Long Island Ice Tea’s prior to driving it- I was all over the road!!! I immediately hit tab and launched the ‘Analog Controls’ portion of the menu, and dropped that analog dial setting back to 100%. After I exited the menu, the controls were MUCH better, but now, in my opinion, a bit too low. I went back in and bumped the sensitivity up again, but this time only to 150%. After playing about 10 games back-to-back (big grin), I settled on a dial setting somewhere around the 150-mark (it may be at 152 now)- I was just so happy that it was working that I didn’t write down the exact number. I continued playing the game until about 10PM last night, totally overjoyed by the fact that this cockpit game, which has been sitting dead in my (g)arcade for over 7 months, was now not only breathing with new life, but its original controls were being used with a NEW, and in my opinion, much better, game!
I still have to wire up the shifter and the gas pedal (which I now know how to do), and then will come the final test of trying to sort out the controls I’m using against the Shiftermame 125 software I downloaded. Either way, I’m simply happy that the steering is working. In my opinion that’s the hardest part to set up if you want to use an original arcade wheel.
I hope that this post/thread/article will help some others out there who, like me, were somewhat apprehensive about using this technique to get a driving game into their home lineup. I am so happy that I went this route with this game!