There are two general kinds of problems that cause this: hardware and software. Let's take on the first one. Are the cables snug? The only other thing I know to check is boot order. With older SCSI devices you have to have them booted up and waiting (for up to 10 seconds) so that they're spun up by the time the computer boots up. So try doing that and see if that works.
If the drive isn't formatted or if something is toasted on the IIC, then you're out of my league! Best of fortune!
~Tarage Dave A. wrote:
I'm just getting back into using an Apple // after many years of PC 'fun'. Have managed to get my hands on a //c with External Disk Drive but every time I switch it on, it gives me the error message "Check Disk Drive". I have to admit that the lessons learnt in all my years of Apple tinkering have deserted me and I cannot remember what this indicated......Have tried all sorts of program disks, etc. to no avail. Any help/comments gratefully received!