So I have an Apollo 13 and the GI relay is a real seizure-inducing thing during 13-ball multiball, especially with LEDs in the game.
I know there is at least one solution for this commercially, but before I spent the money I decided to try the $1 solution, and I like the results!
It's simply this: Put a 7.5 ohm, 10w power resistor across the GI relay's power terminals. Since the voltage is a nominal 6.3VDC even if you have incandescent lamps (some or all) in the game this should be safe (Ohm's law; 6.3 = I * 7.5 or ~.85 amps @ 6.3V = 5.3 watts, well under the 10w dissipation rating of the resistor in free air, even against a dead short on the load side.)
The result is that you get about 30-50% brightness on the GI when the relay is off, and full when on. It completely eliminates the "seizure effect" from the game doing the flash-the-GI thing and yet leaves the desired GI effect intact -- and while it's nowhere near as nice as the board option in terms of optionality it has the very distinct advantage of costing a buck to implement.
This may have been done before (probably has), but if so I couldn't find a thread on it here.... here's where the resistor goes on the driver board. Make sure you use heat-shrink on the leads as the mounting plate is of course grounded, and if you like it you probably want to hot-glue the leads to the board so vibration is relieved and doesn't risk breaking free the solder connections. (A short to ground will not harm anything because the resistor prevents the current from exceeding 0.85 amps, but a short to any other power source could, of course, be disastrous.)
Hillsboro, OR
