TEC FD-50x drives - known issues?

A disk drive performs several different functions. In particular, it rotates the disk, it detects the index hole and write protect notch, it moves the heads between cylinders and detects the track0 position, and it actually does the reading and writing. Do you know which, if any, of these systems are working? Can you get the disk to spin? Do you get an index pulse? Can you get the head to move? And so on. A drive exerciser is handy for this, but by no means essential. You can often get away with just pulling pins on the interface connector low with bits of wire connected to the 0V line. And look at the outputs with a logic probe. Remembr there output drivers are open-collector, so you need to add terminating/pullup resistors (traditionally 150 ohms to +5V) for tssting. Note that some drives with a big ASIC or microcontroller on them do some kind of power-on initialisation. In particular, a few drives do odd things if inputs are held active (low) at power-on. Other drives will ignore all inputs if the power-on seek-to-track-0 fails. If you have one of the latter units, you should be able to see transitions on the stepper motor drive outputs just after power-on. And you can check the track0 sensor by hand, of course. I can't believe it would be that hard to trace out a schematic. Even if there's a big ASIC in the middle of the board (likely on half-height drives), you can often figure out what it's doing from the surrounding circuitry. You can at least check if things like senosr inputs do the right things as you move a bit of card in and out of the sensor, etc. -tony