I've got a Apple IIe which came with a Disk ][ interface card. (With the 2 x 20 pins connectors)
I've also bought a Disk ][ Floppy off eBay which was sold as faulty. It would not spin up and after testing all the chips I found a dead chip on the speed controller board. Replaced and the drive appears to work in that it does all the right actions, but I cannot read/write any disks.
My issue now is I'm not sure if its the floppy drive, or the interface card that is faulty. I'm beginning to think the interface card as I've also built a sdisk2 and can't get that working either. (But it could be a case or either/or both being faulty)
Is there any standalone testing (maybe with some kind of looback connector) I can do on the interface card to first make sure that is working as expected (The obvious test would be to test it against a known good floppy, but there lies the problem)
I've tested all the logic chips on the interface card and they all work fine. Nothing is getting warn on the card either.