Quoted from Robotworkshop:
If your game won't boot without the adapter I would suspect your ribbon cables going to the original sound board. If they are off a pin, swapped, reversed, etc the game won't boot. Those cables are easily put back on wrong. Lots of people have done it. I've taken good pictures of mine and the cables are marked.
Robotworkshop Those are great suggestions. I put a label on each of the various connectors that came out of the MPU before I unplugged it and took several before pics to be sure I put it back right. I did note there are actually two cables from the old SB and I labeled them so I would put them in right, but I could be wrong. I did not remove any pins, the last two had been removed by a previous repair (I assume there was some solder in the holes but no pins). I have the game all put to sleep for the night but will be back at it tomorrow afternoon and will take some pictures of the adapter and the MPU itself. This game technically "worked" when we bought it but I have had to do a lot of cleaning and resoldering of connections all over under the playfield. The last week alone I spent fixing stripped post holes (I did at least 10 dowel+glue fixes on the playfield). I also have a half-dozen lights that don't flash or light when they should. Otherwise it did work before today, but I didn't just put in the J5 adapter, I had to remove the board and solder in the two missing pins (I am not the steadiest hand either so who knows).
I will triple check the orientation of all the connectors to the headers and see what I can do then post some pics tomorrow afternoon.
DickHamill Thanks for the speedy reply!
I get 4 flashes and a solid light on the MPU, and the Arduino lights as well like it is booting. When I have the SB-300 only plugged (adapter off) in I get some of the game sounds and boot beeps like normal but only the GI lights . Fortunately this is my "shop" game and even though I have it next to my other machines, it is okay to be offline for a day or so (I can get practice on my Breakshot and Goldeneye )
I am going to check things tomorrow with the multimeter and see if anything is screwed up. I will post pics if I can't get it sorted everyone is so helpful I am confident I will get it there eventually.