Path: utzoo!utgpu!water!watmath!clyde!rutgers!mailrus!ames!amdcad!sun!pitstop!sundc!seismo!uunet! From: prindle@NADC.ARPA (Frank Prindle) Newsgroups: comp.sys.cbm Subject: 1541 disk alignment (1541 Physical Exam) Message-ID: Date: 9 Feb 88 17:30:35 GMT Lines: 23 One of the best apparent 1541 alignment programs is called "1541 Physical Exam". The disk supplied contains several tracks on which some sectors have been recorded exactly on track, some off center to the inside, and some off center to the outside. The off center tracks are recorded at a variety of different distances off center. When you run their alignment program, it shows a graphical representation of which sectors are not experiencing errors. If the drive is properly aligned, these will be evenly distributed about the correctly centered sector; out of alignment drives will show an abnormally large number of off center sectors (either inside or outside) which read correctly - the graphical display will be off center. To align the drive, loosen the stepper holding screws and rotate the stepper motor slightly, repeat the test to see if the display is more or less centered, etc., etc., etc... The program also diagnoses worn stepping mechanism (does not position head to same position when stepping from opposite directions) and, of course, speed variation from the ideal. This method of alignment closely approximates a *real* alignment disk which contains an analog sinusoidal waveform recorded in an eliptical track. In this case an oscilloscope is used to observe the waveform output from the head, which should show equal attenuation as the eliptical track moves to the inside and outside of the true on-center position. Such a disk is very hard to come by, as previously mentioned. The "1541 Physical Exam" is $39.95 from Cardinal Software (800-762-5645). I use it and it works well.