You're good on connections. The problem is that you have a low 5 volts. Each board by itself will run fine on the bench, but with the "strain" of flippers, the voltage is dropping too low. There's a leg on the u218 chip on CPU board you can cut, if it isn't, to increase the amount the voltage can drop before it resets. There's also a pot on the power/driver board you can adjust (R116) to increase it. Or have your tech rebuild the 5v power part of your power/driver board. Usually the bridge goes, but there are other parts that can fail as well.

Hi everyone, read the thread above and I'm experiencing similar issues. Does anybody have more details about the Sega service bulletin Nr 112?

The game is 'freezing' often during heavy multi ball gameplay. All boards have been serviced, tested and repaired where necessary. Game also has a new DMD controller board.

The fault causes the game to 'freeze', its goes dead with nothing on except for GI. I've read about flipper diodes, BRDG21 possibly needing replacement, but I would perhaps like to try this Sega SB first.

Many thanks in advance.

Most of the time this is caused by low or fluctuating line voltage that dips below 109 VAC. Thoroughly test your line voltage. If you want to try the mod, it increases watchdog tolerance from 5% to 10% by clipping pin 3 of the DS1232. Sega started performing this mod during production so some games may have the mod already. Details here: http://arcarc.xmission.com/Pinball/Stern%20Service%20Bulletins/sb/sb112.pdf

Many thanks for the reply. Interesting that this game was set to 230V (came from the UK) on the jumper settings and we have now changed it to 218V (220V is the nominal voltage here in the UAE) and it appears (hopefully) that the reset issue has been resolved. Will continue to monitor.

Interestingly I inspected the machine to see if the above SB had been incorporated - the U218 chip on the CPU board hasn’t been clipped (although the board was sent away for service) but the U210 chip on the I/O board has......hmmmm.

Anyway - thanks again. Hopefully we have found and cleared the problem!

Good work swampy