jcs@zodiac.phy.duke.edu (03/07/91)
Dear folks, Last night the 800k internal drive in my mac (1985 128 upgraded to a 512k and finally third party SCSI and 1meg) stopped working. In particular, it seemed to work fine reading a disk, but would take a very long (minutes) time writing a file (a few k) at which point any subsequent disk accesses would result in the "This is an unreadable disk, shall I initialize it..." dialog. Writing folders to disk yielded some files unwritable. This morning I swapped the drive with a 800k spare (from my brother's SE HD upgrade). The new drive works ok now (I had to use the new drive but the original cable, using the SE cable caused the drive to try to eject and hang the mac at startup; I don't know why). The old drive had dust and cat hair in it, not to much but some. (I have two cats and a fan in the handle which may suck air through the drive...). My questions are: a) How do I clean and realign the bad drive? b) Will I have any trouble using the SE drive in my Mac pseudo-Plus? c) What is the difference between the SE and Plus cables? d) I have an old 400k drive case (the drive is dead). Is there a prescribed way for hooking the repaied internal as an external? (I have checked Pina's book with no success...) Thanks in advance, John Swartz -- John C. Swartz 1-919-684-8279 Duke University Dept. of Physics jcs@phy.duke.edu Durham, N.C. 27706
davisson@milton.u.washington.edu (Gordon Davisson) (03/10/91)
In article <22046@duke.cs.duke.edu> jcs@zodiac.phy.duke.edu writes: >[A tale of floppy drive woe and swapping.] >My questions are: >a) How do I clean and realign the bad drive? Realigning is difficult and shouldn't be necessary (unless one of the heads is bent or something, in which case you're SOL anyway). For cleaning the heads you want a mild solvent and a nonabrasive lint-free applicator. A VCR head-cleaning kit (the kind with the foam-tipped swabs) should do nicely. The main thing you have to watch out for is bending something -- especially any of the sheet metal hinges they use on the upper head arm and the heads themselves. >b) Will I have any trouble using the SE drive in my Mac pseudo-Plus? You shouldn't. Apple uses the same mechanisms in both. >c) What is the difference between the SE and Plus cables? Your 512's cable (it has a yellow stripe marking wire #1, rather than red, right?) has wires 9 and 20 cut or missing (look closely at the ends of the cable). The new-style 800K drives run the eject motor continuously if these are connected (the reason it works on the SE is that the SE has nothing connected to these pins on the motherboard). >d) I have an old 400k drive case (the drive is dead). Is there a > prescribed way for hooking the repaied internal as an external? I know someone who did this, but I'm not sure exactly what he had to do. I expect that, while you may have a little trouble getting the mounting right, the cabling should be straightforward. Just use the cable from the old 400K drive. It doesn't feed the signal (actually the -12V power supply) through to pin 9, but it does feed the PWM (motor speed control) through to pin 20. I *think* that the PWM signal won't cause a problem, but if it does, cut the gray wire at one end of the connector. (Mind you, I don't *guarantee* it'll work...) -- Gordon Davisson Westwind Computing (206) 632-8141 4518 University Way NE, Suite 313, Seattle WA 98105