I picked up a Black Knight recently. Has RottenDog MPU and power boards in it. Seems to be just fine until you engage 2 flippers at the same time. Either lower left and right, or both lower and upper for one side. So, if you hit both flipper buttons at the same time, or quickly hit one button all the way, the game completely resets.

I fully replaced all 4 flippers and added caps to each one. Installed brand new flipper buttons. Also, disengaged the under play field and coin door slam tilt switches just in case.

Any ideas what to check next? With the MPU and power board replaced, not sure what else could be the problem. All the connectors look like they were rebuild and are nice and clean. Solenoid bridge rectifier? Could the RottenDog boards have issues?

Thanks.

Thanks. All new flipper coils and new diodes. New flipper switches. Didn't change things much. Ill start looking at the power to and from the board to see what I can find.

Thanks for the suggestions. Put in a new Rottendog power supply board and it worked......for like 20 minutes. Got the first multi ball and it reset. Now its back to resetting whenever you hit both flippers at once. Interesting though, you can hit upper and lower flippers on either side now without it resetting, which wasn't the case before. I did put new flipper switches in.

In addition to all new flipper assemblies, including diodes and EOS switches, I also reset the Rottendog MPU board. Tested all the switches and cleaned it.

Next steps that I can think of would be to rebuild all the connectors and replace the solenoid bridge rectifier. The connectors on the BR are all corroded to the posts. So, probably time to replace it.

Any other ideas?

Thanks again.

I do, thanks. I had read that in a FB thread and added them when installing the new flipper coils and switches.

I might end up ordering this BR replacement from Marcos. Its a bit pricey compared to putting a new BR in, but sounds like it is a good upgrade taking out the large cap and replacing both bridges. Anyone have experience with it?

http://www.marcospecialties.com/pinball-parts/5040-09051-RC

From what I know, the capacitors act as spark suppression and are on a lot of early model machines. The person who said they were necessary with the rotten dog board didnt have a lot of theory to support it so you most likely don't need to worry about it (plus they are such a pain to install).

Check your end of stroke switches on your flippers to make sure they are clean and gapped correctly. Thats a pretty big source of flipper issues on this era machine.

Good to know.

I thought this video did a great job of explaining everything when it comes to flippers and rebuilding. He explains the anti-spark caps. Interesting that its to prevent electricity from jumping the gap on the EOS switch.

Install the rectifier board and same results. If you hit all 4 flippers at once, it instantly resets. Not sure what else to check at this point.

There is an aftermarket board I mentioned in a previous post that replaces the two bridges and the big blue cap.

http://www.marcospecialties.com/pinball-parts/5040-09051-RC

Thanks. I have with the power board, one brand new. I have two and have swapped them back and forth with another machine.

Im going to try swapping the driver/MPU board on someone else's machine.