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PgrAm
May 21st, 2012, 05:08 PM
There is a 20mb drive installed in my mac SE but its having a ton of problems.
When I start up the computer it will begin fine and show the finder icon but then stop before "welcome to Macintosh" and then give me a ? floppy.
When I start up using a boot disk the drive will not be recognized unless I tap the side of the case in a specific spot.
At first I thought it was a loose connection but I have opened the case and reseated all the applicable connections.

Any ideas what could be wrong and how I might fix it?

twolazy
May 21st, 2012, 06:00 PM
Apple floppy drives are known for getting a bit uhm touchy when not used for a long while. Try getting the system to boot off the floppy, and eject and insert the disk a few dozen times. Should work fine after that and maybe a cleaning.

As for the hard disk not starting, could be many things , from a non apple drive to just needing to be reformatted, or a bad/dirty terminating resistor. Hard to say without seeing it in person. Are there any weird clicks or noises?

PgrAm
May 21st, 2012, 07:20 PM
Apple floppy drives are known for getting a bit uhm touchy when not used for a long while. Try getting the system to boot off the floppy, and eject and insert the disk a few dozen times. Should work fine after that and maybe a cleaning.

As for the hard disk not starting, could be many things , from a non apple drive to just needing to be reformatted, or a bad/dirty terminating resistor. Hard to say without seeing it in person. Are there any weird clicks or noises?

Floppy works fine all the problems are with the hard drive. I'm sure it's an original apple 20 MB drive, I have booted off it once but it never worked after that, it's just very intermittent so much that it wont stay on long enough to work. I'm sure all the connections are tight as I tested them with a multimeter. Where is the terminating resistor (internally)?

krebizfan
May 21st, 2012, 07:57 PM
Floppy works fine all the problems are with the hard drive. I'm sure it's an original apple 20 MB drive, I have booted off it once but it never worked after that, it's just very intermittent so much that it wont stay on long enough to work. I'm sure all the connections are tight as I tested them with a multimeter. Where is the terminating resistor (internally)?

It depends on which hard drive is actually installed. Apple wasn't making the drives. One source I have suggests Apple often used Miniscribe drives which guided the terminating power through a fuse. If the fuse blows, the drive won't work. There should also be a couple of resistor packs either on the bottom or back which are the physical terminators.

Make sure the SCSI cable hasn't been crimped or damaged. The SE is fairly cramped which makes it easy to bend the cable to excess.

http://stason.org/TULARC/pc/hard-drives-hdd/miniscribe/M8425S-21MB-3-5-HH-SCSI1-SE.html which is a reference to one model of hard drive that shows up in some SEs. You might have a different model though.