armhold@topaz.rutgers.edu (George Armhold) (08/19/89)
Hi, I'm working in an environment where I'm shuffeling between an A1000 at home and an A2000 at work. It seems that one of these machines (or possibly both) has an alignment problem with one of their floppy drives. Sometimes when I try to boot from a Workbench disk the machine just grinds away at the disk. It takes about 5 minutes to boot from a disk that usually boots in 3. If I try booting a few times the problem sometimes goes away. I used to fix this problem in the past by simply replacing the bad disk, but this is starting to happen on 1 week-old disks now. Are there any programs in the public domain that will test the alignment of a disk drive? Thanks, -George
douglee@becker.UUCP (Doug Lee) (08/24/89)
In article <Aug.19.12.26.52.1989.18198@topaz.rutgers.edu> armhold@topaz.rutgers.edu (George Armhold) writes: > >Hi, > I'm working in an environment where I'm shuffeling between an >A1000 at home and an A2000 at work. It seems that one of these >machines (or possibly both) has an alignment problem with one of their >floppy drives. I suggest that you disassemble your drive and give it a thorough cleaning with PURE isopropyl alcohol, especially the heads, but be sure and clean out any hair or fuzz that may be migrating to the head area. Also make sure that nothing is blocking the optical sensors for track 0, write protect and disk inserted. Some drives have little mechanical switches for disk inserted and write protect. Make sure they move freely and aren't bent. If they are bent and binding, bend them back VERY carefully. >Are there any programs in the public domain that >will test the alignment of a disk drive? To do this, You need and oscilloscope and a special alignment disk made on a calibrated drive. You can get these from drive manufacturers and people who make drive testing equipment. I got mine from a company called Lynx in Markham Ont Can, who make drive exercisers. It cost $100.00 Can. Once you have one of these, you have to move the head to the track indicated on the disk where a ' cat-eye ' pattern is found. What this amounts to is a couple of analog signals recorded just before and just after the track you're on. Their amplitudes change sinusoidally, and are out of phase, so the result is that you see two humps on the oscilloscope, which should be of equal amplitude. If they are not, you have to loosen the screws holding the head stepper motor and rotate it. This is VERY touchy and you could easily lose the track you're on completely. If this happens, just step the drive in and out until you find the signal, and then you know where you are and which way to adjust. Unless you feel comfortable with mechanical stuff requiring extremely delicate tweeking, you may not feel like doing this. The other part is adjusting the index pulse from the drive so it matches areference pulse recorded on the disk. In other words, you want the index pulse out of the drive to happen at the proper time relative to the pulse recorded on the disk. I forget if it's at the same time or there is an offset, without hauling out a drive manual. The oscilloscope must be a dual-trace model and is connected to test points in the drive, with the scope channels added together and inverted with respect to each other. The test points are on the front of the NEC drives, beside the light connector. (The two outside ones). On one variation of Matsushita drive, the test points are on the bottom labelled T1 and T2. You will have toi solder little wires to them to hold the scope probes on. Various models of drive will be different. As far as software, I have just hacked on the example trackdisk device code in the RKM to make it do what I want, for the occasion at hand. You could have a look at this. I have thought of making a program just for stepping drives for servicing, but never gotten around to it. If there's any interest, I may. Does anyone on the net reading this know where to get manuals and parts for all these various floppy drives? If so, mail or a posting would be appreciated. > >Thanks, >-George -- Doug Lee douglee@becker 416-461-5357