info-mac@uw-beaver (01/18/85)
From: decvax!ucf-cs!peora!jer@UCB-VAX Yesterday while deleting some old files from my most frequently-used disk, the finder started behaving anomalously -- the icon outlines wouldn't follow the cursor when moving the icons around, eventhough the icon moved when the mouse button was released; when I tried to launch an application subsequently, I got a "bomb" error code, and upon restarting, a "Sad Mac". After booting from another disk, I inserted the disk I had been using, and was told it was "damaged" and would have to be reinitialized; on reinitializing, the number of blocks in the disk was much smaller than usual, apparently the result of bad sectors. On examining the surface of the disk, I found that the disk surface was uniformly covered with small, comet-shaped marks. These are about 2 or 3 millimeters long on the average, although they vary, and are extremely narrow. One end (the same end on all the marks) is always widest, with the mark tapering off until it disappears at the other end. They resemble scratches, except that depending on the angle of the incident light, the wide end seems irregular in shape. I then examined some of my other disks, and found that others also have the marks, in proportion to their frequency of use. My question: is this a problem common to all (or many) Macs, or is it some peculiar problem with mine? One thought that occurred to me was the recollection of someone in here mentioning that once after his diskette had been spinning for several hours (due to some problem with a software product he was beta-testing), the diskette built up a static charge which caused a spark to jump inside the machine. I wonder if these marks might be the result of small static discharges? However, I would think that such dis- charges would tend to erase data on the disk; and also, these marks do look more like scratches. Any ideas as to what the problem is? To look for these on your disks, slide back the metal cover and hold the diskette such that the light from a lamp is reflected off of it, and rotate the disk with respect to the light source. The marks are most visible on my most heavily-used disks (maybe 20 or 30 are visible at any one time through the slot); they are hard to find on infrequently used ones, and not present at all on unused diskettes. -- E. Roskos jer%peora.UUCP@Berkeley
info-mac@uw-beaver (01/25/85)
From: cornell!vax135!decvax!decwrl!amdcad!fortune!jones@uw-beaver.arpa (Dan Jones) In article <444@uw-beaver> you write: >From: decvax!ucf-cs!peora!jer@UCB-VAX > >On examining the surface of the disk, I found that the disk surface was >uniformly covered with small, comet-shaped marks. These are about 2 or >3 millimeters long on the average, although they vary, and are extremely >narrow. One end (the same end on all the marks) is always widest, with >the mark tapering off until it disappears at the other end. They resemble >scratches, except that depending on the angle of the incident light, the >wide end seems irregular in shape. > I don't know anything about MACs, however, if the MAC floppy has a head load solenoid, your problem would be caused by the head digging into the disk surface when it is loaded. It is an odd problem and I believe in any case you have a bad drive. Cleaning the heads might make a difference. Dan Jones UUCP: {ihnp4,ucbvax!amd70,hpda,sri-unix,harpo}!fortune!jones DDD: (415)595-8444 x 440 USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065