Good evening and thanks for letting me join the group.
I have an Apple IIe that I'm in the process of restoring. It came with three disk drives, two 5.25" and one 3.5" Unidrive, but no disks of any kind. Out of curiosity, I attached the 3.5" drive and started the computer. I was greeted with "static" on my monochrome monitor and after a moment, I saw a small curl of smoke coming out of the computer. After shutting it down and cracking open the case, I saw that the ribbon cable from 5.25" controller card was scorched. It wasn't evident from the outside that there were separate 3.5" and 5.25" ports. After seeing this I connected the correct drives to the correct controllers and everything seems OK. The computer then started up the the "apple II/e" screen. Did I ruin anything?