Quoted from wolffcub:
He has been eagerly helping me. He and myself are puzzled as to why this is happening on both the flash Gordon and f2k machines. When using his MPU with his new driver board the MPU will not finish booting, But if i change back to the old driver board it boots perfect. We are going to be doing more testing later today after work.
I think I figured out what is going on. I was able to get nine ball to boot up every time by removing the capacitors on the mosfet drain pin. The drain capacitors is 0.1uF across ground the drain pin of mosfet which runs out to the coils. When the mosfet is turned off the 43v feeds back through the coil windings up to the driver board. If enough coils are used enough capacitance is added to the 43v rail to break the zero cross detection that monitors the 43v suppy pass zero at 120hz to be used as a timer.
I have had those capacitors installed in the boards for a long time now and this is the first time I have found it to be an issue. Maybe the last batch of capacitors i got are actually over 0.1uF in rated. When the game started working the capacitance was probably dropped down as things heated up and the zero X detector started working again.
I was trying to be extra thorough and using those capacitors there but I think it causes problems in rare cases and the benefit is minimal. The other replacement sdb designs do not appear to be using those capacitors, or a gate capacitor. I will not populate those caps going forward and delete them from the design in the next revision.
Wolfcub if you cut out C301 to C319 on the driver board problem should go away.