Quoted from Jaketime81:Also, there are 4 or 5 different multiball modes during game play that turn the magnet on, are all three magnets supposed to turn on together every time? or do they turn on induvidually depending on which mode is activated? I would guess seperately because there are 3 input and output circuits!?
One problem with this board (the way it was designed originally) is that the magnet driver transistors are driven from a chip that is sent a serial string of data that is clocked into the chip. The data is generated and clocked by the MPU.
This works well UNTIL that data is corrupted by something. Perhaps a spike on the input wires running past several coils? No one has proven for certain what happens but the point is the wires feeding these rather delicate signals run a very long way from the MPU in the backbox to the magnet driver board under the playfield. These wires are not shielded and, as mentioned, are carrying pretty critical signals that, if corrupted, can send incorrect data to the decode chip on the magnet board.
This can then result in the decode chip losing its way and driving incorrect outputs or locking outputs on without the MPU knowing this is what has happened.
This is a all a basic design flaw right from the original design. The only way to start addressing the issue is to remove the very long data lines and move the solenoid driver board to the backbox, as close as possible to the MPU so that the critical data wires are as short as practicable and then run heavy coil driver wires from the new location to the magnets under the playfield.
Owners that have done this report that they have had no more problems with the magnets locking on or behaving mysteriously.
It's a bit of work to make this mod but, in the long run, is probably worth the effort.
Richfield, MI
