When I switch on the power to my Williams Laser Ball all of the solenoids fire once (all at once.. not sequenced). Can anyone confirm that this is (or is not) normal? Seems odd to fire the solenoids all at once upon power up. Thanks!

Thanks... will look at that. Didn't think it made sense.

From the schematic it appears that the blanking signal must be high (5v) to enable a solenoid to fire (blanking signal is 'ANDed' with the PIA sol output signal). The MPU activates the blanking signal (5V) once it has successfully booted and is able to control the PIA outputs.

I've put an o-scope on TP4 (blanking) and see the 5V signal. Obviously when I turn off the machine it falls back to 0V. I then pulled a rom (to ensure that the MPU doesn't properly startup) and turned on the machine. The blanking signal stayed 0V (as expected)... thereby proving that the blanking signal wasn't shorted on. I also checked the blanking signal on the Driver board and it looks ok. So... the blanking signal appears to be working normally.

I'm now suspicious of the RESET circuit. On my machine the RESET signal goes high immediately upon application of power. One document I have says that there should be a 1 second delay. Another document says 1ms. Obviously a major difference. Anyone know which is correct?

Thanks!