Damage from reversing floppy drive cable?

Question

Level 2

180 points

Damage from reversing floppy drive cable?

Is it possible to damage any components of a beige G3 if the floppy drive cable is accidentally reversed? Could you damage the floppy drive or even the motherboard considering voltage would move through the floppy drive the wrong way?

You see, by accident I reversed my beige G3's floppy drive cable and turned on the computer. Later I realized what I had done and I am a bit concerned that I may have possibly damaged something. (Due to another CD-ROM issue I still haven't booted it up successfully yet to see if it still works- noted in a separate post.)

The reversal of the foppy drive cable occured after I built my own floppy drive cable (the 20 pin floppy cable) by modifying an old 40 pin IDE cable - essentially I cut it in half - carefully - not a small operation I must say. My new modified cable did not have any notches that help inserting the cable the correct way. By accident I put the cable in the wrong way and turned on the computer. I am now realizing that this may have been a bad idea and so I am now going to use the proper notched cable. I hope I didn't damage anything.

Could I have damaged any electrical components when I made this error?

Thanks

PS. Any idea where I could buy a new floppy cable? Are they still manufactured or are they now obsolete? I would need the 20 pin type with 20 cables - ribbon style. Or does anyone know where I could buy just the 20-pin connectors and some bulk 20-pin ribbon cable so I could build my own?

g3 beige 233 MHz, Mac OS X (10.1.x), 384 RAM

Posted on Jun 7, 2006 10:10 AM

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Answer 1

Jun 10, 2006 12:49 PM in response to rainforest

rain,

Once again, find a local computer recycler. A box of cables tipped over in my driveway and reminded me that WSU dumps these cables by the boxful. If you were closer, you could have a dozen. : )

Jim

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Answer 2

Jun 10, 2006 4:01 PM in response to rainforest

I'm sure you didn't damage it, at least not the motherboard. I don't really know exactly how it all works on an electronic level, but I'm pretty sure you should be fine. Of course, I'm also pretty skeptical about being able to "make" a floppy drive cable... ATA cables are able to carry a lot more data than is a floppy drive cable, so I doubt they're compatable, even with equal wiring, but I could naturally be wrong.

You could probably find a cable really cheap on eBay or the like..

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Answer 3

Jul 9, 2006 7:25 PM in response to tonto cat

tonto cat,

You are going to have to find a machine or two as a bridge over the two decades of technology you are trying to span. A IIGS is the easiest way to read 5.25" disks and have a 1.44 MB 3.5" floppy to get you up to a PPC with USB, most likely a platinum G3 with a USB card.

Ji˜m

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Answer 4

Losmeme

Level 1

45 points

Jul 11, 2006 6:34 AM in response to rainforest

Not sure that you would damage components, but cutting down a standard IDE cable to use as a floppy shouldn't work. Floppy drive cables reverse a pair of leads in the middle of the cable, which doesn't happen on the IDE cables. Floppy cables are cheap, buy a new one!

Furthermore, IDE cables often times cut out a single lead in the middle of the cable. This matches the blank pin on newer cable, I believe.

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Answer 5

Jeff

Level 6

12,328 points

Jul 11, 2006 9:36 AM in response to Losmeme

Unlike the inverted conductors found on the floppy disk drives in PCs, the Mac's FDD uses a straight-thru ribbon cable, similar to that used by IDE and ATAPI devices (except for the reduced number of conductors).

As for the "cut" conductor found on some ribbon cables, that's for pin 28 on cable-select cables. Other cables accomplish this by leaving out the piercing pin in the middle connector, so that the cable select signal is only conveyed to the last connector. Since the Mac FDD ribbon cable only has 20 conductors, one could tear an IDE/ATAPI 40-conductor cable down the middle, so #28 is a non-issue.

Obviously, the sure-fire means of maintaining correct orientation when inserting a ribbon cable, is with a keyed connector or proper use of the conductor with the tracer.

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Answer 6

Jeff

Level 6

12,328 points

Jul 11, 2006 9:46 AM in response to rainforest

" By accident I put the cable in the wrong way and turned on the computer. I am now realizing that this may have been a bad idea and so I am now going to use the proper notched cable. I hope I didn't damage anything."

The Mac FDD ribbon cable also conveys DC power, because the drive has no separate power connection. Inverting the connector undoubtedly sent the DC voltage through the wrong pins - either data pins (or unused ones - if any). If the computer and the FDD are functioning properly after correcting your oversight, then no lasting damage was caused.

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Answer 7

tonto cat

Level 2

430 points

Jul 9, 2006 5:54 PM in response to rainforest

I guess what we all need is a USB, external floppy drive.

does anyone know of such an animal ? especiall one that reads both the 3" hard and the very oldest 5" soft discs.

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