This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
Try removing the drive which was connected incorrectly. If your system boots from the remaining drive (connected in the Drive One position), this is a fairly good indication that the Disk II card and IIe are okay and that the removed drive is messed up. If it looks like a drive is bad, remove the cover and inspect the drive's main circuit board for blown components. If nothing obvious shows up, a decent fix try is to replace the 74LS125 IC on the drive's main circuit board. (Also, see Q&A 013.) ---------------------------- By: Ryan Underwood I accidentally offset a row of pins on the //e disk controller card when plugging one of the drives in. Snap, crackle... you get the picture. I opened up my freshly fried Disk II, and in the center of the board there is a 74LS125 that is blown. Replaced it (it was socketed) with the same chip from another Disk II, and voila! it works again. I would reasonably assume that misaligning the drive connector on the controller is what blew the 74LS125 in several Apple II drives before they got to me. Note that while the genuine Apple Disk II simply lights the LED and doesn't move the head at all when this IC was blown, a Mitac drive actually ate disks. So any number of dead Apple II drives with different symptoms could have a blown 74LS125. ___________________________ By: Rubywand
 
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