miker@orca.UUCP (Mike Reiney) (08/11/83)
The 1540/1541 disk drive is designed such that the stepper motor limits its travel by bashing itself against the stop. It doesn't take long for something to bend or move. I have requested help from CBM but they will not respond. In desperation I loaded the diskette that was supplied with the drive and rotated the stepper motor for maximum output (from the second amplifier stage) while reading the directory. This produced an interesting side effect: If you "new" a disk, you can't read track one. The solution to this problem is to move the stop slightly , new the disk again and check for read of track one using the display track and sector utility. With patience, this technique seems to work. The mechanical position of the track placement is dependent on the positions of the stop, the stepper motor, and how far the motor shaft got torqued out of position while it was banging itself against the stop. A possible cure might be to "new" the disk using a new machine language procedure downloaded into the drive. The procedure would initialize by banging the stop, step out n tracks, step back in n-1 tracks and call that track zero. Initilaization of the disk would then be dependent on the magnetic influences of the stepper motor and not the mechanical influences of the design. The extra step out would insure that the drive could always find track zero. If anyone writes such a routine, I would appreciate hearing about it. In a related issue, I am experiencing another drive problem. When it warms up, my 1540 occasionally seeks past track the last track (35?) and hangs waiting for data that is not there. Mechanically pushing the head back fixes the problem temporarily. I can't find anything wrong and CBM won't respond. Leaving the cover off seems to solve the problem. Any ideas? Michael Reiney 10925 SW Mira Ct. Tigard, Oregon 97223