Hey everybody. I'm curious if any of y'all have experience working on older arcade or pong games. I was recently contacted to help fix up what I believe is a 6 Pac I retrofit board by Venture Line that's integrated into a third party cabinet (Tennistronics?). The unit is old school. All 7400 logic, 555s for timing, and so on. No microprocessors in sight.
The unit's in surprisingly good condition, but has an issue with the 3rd player paddle. It seems that the paddle will always extend from the bottom of the screen to where it ought to be, it's about normal width if you move it to the bottom, or player 3 can move it to the top and just shut down all opposition with a great wall of paddle :3
I've tried some basic stuff like cleaning and reseating connectors (and that got the sound working!), but think this may be a dead logic chip or similar. I have some basic digital experience, and if I were to try to build a discrete pong unit I'd have a circuit that generates a window or threshold from the voltage on the paddle potentiometer, and then use a set of comparators to display the paddle on the right scan lines.
The issue is I don't know enough about arcade machines to know what other logical blocks to look for in the circuit or how to find the interesting bits without doing a complete reverse engineering to make a schematic and dig through it. Does anyone have any experience with these machines or, worst case, would know someone I can refer the repair to?
Attached are two pictures of the display so you can see the issue, an overview of the innards, and a pic of the table so you know what we're working on.
The unit's in surprisingly good condition, but has an issue with the 3rd player paddle. It seems that the paddle will always extend from the bottom of the screen to where it ought to be, it's about normal width if you move it to the bottom, or player 3 can move it to the top and just shut down all opposition with a great wall of paddle :3
I've tried some basic stuff like cleaning and reseating connectors (and that got the sound working!), but think this may be a dead logic chip or similar. I have some basic digital experience, and if I were to try to build a discrete pong unit I'd have a circuit that generates a window or threshold from the voltage on the paddle potentiometer, and then use a set of comparators to display the paddle on the right scan lines.
The issue is I don't know enough about arcade machines to know what other logical blocks to look for in the circuit or how to find the interesting bits without doing a complete reverse engineering to make a schematic and dig through it. Does anyone have any experience with these machines or, worst case, would know someone I can refer the repair to?
Attached are two pictures of the display so you can see the issue, an overview of the innards, and a pic of the table so you know what we're working on.
Attached Files
Comment