TEC FD-50x drives - known issues?
dave04a at dunfield.com
Sat Oct 8 20:51:56 CDT 2005
>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.
This much I actually know :-)
>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.
All functions appear to work (Motor, Index, Step) - problem in all cases
is in the read/write circuitry. Drive goes through all the motions, it
just can't read/write.
>A drive exerciser is handy for this, but by no means essential.
Imagedisk's "Align/Test" function lets me excercise the drive with a fair
bit of manual control.
>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
>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.
All of this works.
>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.
It may come to this - At least I do have a couple of working drives
that I can compare signals with - but I asked in case a) someone has
the technical documentation or b) someone might say "oh yeah, thats
a common problem caused by xxx...", either of which could save me a
lot of time.
I think I agree with Allison however that these drives are crap, and
I'm not sure I want to spend a lot of time on them if suitable
substitutes can be found - in this case, the physical constraints make
this a but more challenging.
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
More information about the cctalk