MBECK@AI.AI.MIT.EDU ("Mark E. Becker") (01/22/88)
Hello All - I'm sure someone out there has solved this problem.. it has bitten me enough so that I'm now out searching for a solution. The configuration: 2 Shugart 851 8" DS/DD drives. 2 NEC FD-1036A 3.5" DS/DD drives. The problem - Turning off power to these drives causes the on-board electronics to "spasm" and write random magnetic garbage on whatever diskette in installed. Of course, the doors are closed. In the case of the 851's, the heads briefly load then unload... the 3.5's spin for a second or two until the power supply drops below some critical voltage. The garbage only appears on a cylinder segment; the cylinder being where the two heads are at when the power drops. I can usually "fix" the 8" disks by re-formatting just the affected cylinder and reloading the damaged files from backup. However, the 3.5" disks resist this and I had to degauss and then re-format. Hardware hacks to solve this problem would be appreciated. Regards, Mark Becker MBECK@AI.AI.MIT.EDU