Working on Bally Star Trek. It was playing fine, so don't suspect any issues with the play field. I upgraded the SDB with new electrolytics, and did the ground mods. When I installed the board I ran through the solenoid self test to make sure all the solenoids fired. About half way through the test, or maybe it completed, not sure, the solenoids quit firing. Checked the 1A slow blow fuse under the play field and it was blown. Don't suspect anything on the playfield, as I said, I was playing fine before I pulled the SDB for upgrades. Could the fuse have been weak? I only have one more fuse and don't want to try it for fear of blowing it and being down and out for the next few weeks. Thoughts?

Found a bad diode, replaced it and the fuse. All ok now.