Exabyte SCSI ID number stuck - need to change! - Storage

This is a discussion on Exabyte SCSI ID number stuck - need to change! - Storage ; Hi, all: I have an old external Exabyte drive, and its SCSI ID number has stuck at "7"... It needs to be changed to any numbers but "7"! The buttons below and above the number display had stopped working. I ...

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Thread: Exabyte SCSI ID number stuck - need to change!

  1. Exabyte SCSI ID number stuck - need to change!

    Hi, all:
    I have an old external Exabyte drive, and its SCSI ID number has stuck
    at "7"... It needs to be changed to any numbers but "7"! The buttons
    below and above the number display had stopped working. I mean, I can
    push them, but they don't change the number. Is there any other way
    to change it?
    Thanks.

    kaori

  2. Re: Exabyte SCSI ID number stuck - need to change!

    In article <5715b7dc.0406151349.fc2291@posting.google.com>,
    kaori@amroutes.org (Kaori) wrote:

    > Hi, all:
    > I have an old external Exabyte drive, and its SCSI ID number has stuck
    > at "7"... It needs to be changed to any numbers but "7"! The buttons
    > below and above the number display had stopped working. I mean, I can
    > push them, but they don't change the number. Is there any other way
    > to change it?
    > Thanks.
    >
    > kaori


    Trace the cable from the ID selector gizmo to where it connects to the
    drive controller board. You should see a double-row of header pins
    there, like so:

    .. . . . . . . . . .
    .. . . . . . . . . .

    Not knowing anything about the drive you've got in the case, I have to
    go on guesswork, but if it's like most SCSI drives, the two leftmost
    pins are "A2", the next two pins are "A1", and the next two to the right
    are "A0". Often (but not always...) that's what the circuit board will
    show somewhere right near the pins.

    So what you've PROBABLY got is something like this:

    .. . . . . . . . . .
    .. . . . . . . . . .
    A A A X X X X X X X
    2 1 0 X X X X X X X

    Each vertical pin-pair, A2, A1, and A0, makes on an "on/off" switch. To
    turn the switch "on", you short the upper pin to the lower one. To turn
    it off, you remove the wire, molex, or whatever is connecting the two
    pins. The pins marked "XX" may or may not be important to your specific
    drive. Don't mess with them unless you *KNOW* what they do on the drive
    you've got, and even then, proceed with caution. Some uses for them:
    Signalling to NOT spin up the drive at power-up, write-protecting the
    drive, timing adjustments, and so on. As you can see, they may or may
    not be trivial. Unless you know *FOR SURE* what each pair does, you're
    better off not messing with them.

    To set your SCSI ID without relying on the (apparently broken) gizmo,
    you need to know a little bit of binary:

    0 = 000
    1 = 001
    2 = 010
    3 = 011
    4 = 100
    5 = 101
    6 = 110
    7 = 111

    Each pair of pins corresponds to a binary value - A0 is 2^0 (1, to
    normal-counting folks), A1 is 2^1 (2) and A2 is 2^2 (4). To figure out
    what the current SCSI ID is, look at which pins are connected together,
    and add them up - so if you were to see a drive with a jumper on A0 and
    A1, you'd basically go "A0 = 1 and A2 = 2, so A0+A2 = 3 means your drive
    is set to ID 3". To select a given ID, you connect one or more pairs of
    pins to produce the ID number you want. Which sets of pins? Convert your
    desired ID number into binary with the table above - 6 in decimal = 110
    in binary, or "A2 on, A1 on, A0 off". So, you'd short together the A2
    and A1 pins, but leave the A0 pins untouched.

    Same thing if you want SCSI ID 5: 5 decimal = 101 binary = "A2 on, A1
    off, A0 on"

    Now, having "taught you to fish" (or at least tried...) here's a
    "cheat-sheet" for SCSI ID settings:

    ID Pins to short Binary value
    0 none 000
    1 A0 001
    2 A1 010
    3 A0 & A1 011
    4 A2 100
    5 A2 & A0 101
    6 A2 & A1 110
    7 A2 & A1 & A0 111 (Most often, the computer itself is
    hard-wired as SCSI ID 7, but that's not carved in stone. To be safe, DO
    NOT use ID 7 unless you've got no other choice.)

    Your little "push the button" gizmo is just a fancy way of accomplishing
    exactly the same thing as the jumpers do, without needing to "think"
    about it or work as hard. When it displays a number, the pins noted
    above are connected, just as they would be if you were using jumpers.

    If you don't have any molex jumpers, strip a few inches of a piece of
    stranded wire, and separate out one of the strands, then wrap it around
    the two pins (being sure not to make contact with other nearby pins) and
    twist it tight like you would the twisty-tie on a loaf of bread. Use a
    pair of nail clippers or similar to snip off any extra "tail", and
    you're good to go. The pins that you're wiring together don't carry any
    serious voltage or amperage (typically 5 volts at some ridiculously tiny
    amperage), so just about any fine piece of wire will do the job - Wire
    size is not critical unless it's so big that you end up contacting more
    pins than you actually intended to.

    --
    Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
    I respond to Email as quick as humanly possible. If you Email me and get no
    response, see Short
    form: I'm trashing EVERYTHING that doesn't contain a password in the subject.

  3. Re: Exabyte SCSI ID number stuck - need to change!

    Thank you so much, Don.
    Kaori

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