Scsi hard drive problems

[Macintoshguy1984]

I recently found a iomega zip 100 drive at a thrift store so i hooked it to the mac then the zip drive had a port for the hard drive so i plugged it in.

Now the computer will not reconize the hard drive. I tested it with another macintosh plus and even another hard drive enclosure but it still wont detect it! The hard drive is also terminated.

 

[Outlander]

I have been having odd scsi behavior on all of my older compact macs from the late 80's. My Macintosh Plus's refuse to boot from any external SCSI hard drives, even one that I had loaded specially for my Mac Plus and was working many years ago before it was put in storage. I can put the HD on my PM 9600 and it comes up just fine, but hook it up to my plus or SE's and some just sit there. I really believe there's some type of filter or scsi termination issue that develops with time. Like how electrolytic capacitors dry up and die with time and need to be replaced. My SE/30's clock also does not work anymore. So there just might be other components that die with time that deal with SCSI operation. It's beyond odd.

Also be sure you picked up a SCSI zip drive and not a parallel zip drive as plugging a PC zip drive into the SCSI port would probably kill it.

 

[Macintoshguy1984]

The zip drive was parallel [] ]'>  but i think the drive is broken not the port because i tried it in a different enclosure and different mac and the drive didn't work. is there anyway i could fix it?

 

[Cory5412]

A parallel port zip drive will not work on SCSI, even if you take it out of its enclosure and connect it... somehow.

That drive will only work on computers with parallel ports.

Did the SCSI hard disk work before you added the Zip drive, and that's now not working?

 

[Macintoshguy1984]

Yes the hard drive was working before i plugged the zip drive into it

 

[techknight]

Yikes! that was literally the WORST thing you could have done. 

You probably fried the SCSI IC. There is another thread here which is recent that the same thing had been done, and if I recall, the OP couldn't fix it even after changing the IC, and its somewhat possible you fried the SCSI controller in the hard drive itself as well. Its on the same bus! if the HDD doesnt work in any other machine now, toss it. And if your current machine now doesnt work with any known good drive, well... 

With that said, its likely you will need a new board unfortunately. You live and learn

Worst thing I had ever done was try and get ethernet by forcing a nubus card in backwards on the SE PDS. (I didnt know any better back then). I killed both the motherboard and the card! never could get rid of that checkerboard pattern since then

 

[Macintoshguy1984]

What is the reason for the ports getting fried?

 

[techknight]

because you plugged a parallel zip drive into it. SCSI and Parallel devices are wired very very differently.