Certain MiniDin 6 Pinouts Cause Problems on KVM Switches

Discussion in 'IBM' started by Will, Aug 5, 2006.

  1. Will

    Will Guest

    We have a lot of server room computers hooked up to Belkin 16 port switches.
    What we noticed is that maybe 10% of the 6 foot Belkin "all in one" cables
    we buy end up causing sporadic problems, such as the keyboard disappears for
    a given server.

    We have a continuity tester, and I noticed an interesting result on these
    cables that maybe some engineer in the group could give me more information
    about.

    First, according to the published standards I could find, the correct wiring
    of the 6 pin mouse and keyboard PS/2 cables on the minidin 6 type connector
    are as follows (pins one through six in order):

    1=data
    2=not connected
    3=ground
    4=+5V
    5=clock
    6=not connected

    With all of the longer Belkin All In One cables (15 to 25ft), the 6 pins on
    the minidin 6 are all connected end to end, and there is no ground
    connection on pin 3. We have no problems with those cables.

    With the cables that are causing us problems, we measured this result on the
    pins using our continuity tester:

    1=connected
    2=not connected
    3=data is not connected, but ground is connected
    4=connected
    5=connected
    6=not connected

    The cables that cause us problems seem to follow the standard, whereas the
    cables that don't cause problems ignore the standard and just connect all
    pins.

    Is it possible that the problem here is the ground connection on pin 3?
    Maybe the wiring never gets to a true ground, and there is some kind of
    ground loop?

    If this is a possible cause for the observed symptoms, how could I confirm
    it?

    --
    Will
     
    Will, Aug 5, 2006
    #1
    1. Advertising

  2. Will

    Guest

    On Fri, 4 Aug 2006 21:54:41 -0700, "Will" <>
    wrote:

    >We have a lot of server room computers hooked up to Belkin 16 port switches.
    >What we noticed is that maybe 10% of the 6 foot Belkin "all in one" cables
    >we buy end up causing sporadic problems, such as the keyboard disappears for
    >a given server.
    >
    >We have a continuity tester, and I noticed an interesting result on these
    >cables that maybe some engineer in the group could give me more information
    >about.
    >
    >First, according to the published standards I could find, the correct wiring
    >of the 6 pin mouse and keyboard PS/2 cables on the minidin 6 type connector
    >are as follows (pins one through six in order):
    >
    >1=data
    >2=not connected
    >3=ground
    >4=+5V
    >5=clock
    >6=not connected
    >
    >With all of the longer Belkin All In One cables (15 to 25ft), the 6 pins on
    >the minidin 6 are all connected end to end, and there is no ground
    >connection on pin 3. We have no problems with those cables.
    >
    >With the cables that are causing us problems, we measured this result on the
    >pins using our continuity tester:
    >
    >1=connected
    >2=not connected
    >3=data is not connected, but ground is connected
    >4=connected
    >5=connected
    >6=not connected
    >
    >The cables that cause us problems seem to follow the standard, whereas the
    >cables that don't cause problems ignore the standard and just connect all
    >pins.
    >
    >Is it possible that the problem here is the ground connection on pin 3?
    >Maybe the wiring never gets to a true ground, and there is some kind of
    >ground loop?
    >
    >If this is a possible cause for the observed symptoms, how could I confirm
    >it?


    By "ground" you mean the plug shell? Real IBM keyboard cables use the
    shell connection for the ground braid and use the pin 3 for an
    isolated DC signal ground. Your problem could be caused because these
    get mixed up in some cables.
     
    , Aug 5, 2006
    #2
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Medical Physics

    KVM switches and wireless keyboard/mouse

    Medical Physics, Aug 22, 2003, in forum: PC Hardware
    Replies:
    0
    Views:
    400
    Medical Physics
    Aug 22, 2003
  2. Mark Carroll

    KVM switches - awkward situation

    Mark Carroll, May 13, 2004, in forum: PC Hardware
    Replies:
    2
    Views:
    270
    Mark Carroll
    May 26, 2004
  3. eöl
    Replies:
    4
    Views:
    664
  4. sqrfolkdnc

    problems with Apex 8001/KVM-DT KVM switch

    sqrfolkdnc, Sep 29, 2005, in forum: Sun Hardware
    Replies:
    5
    Views:
    347
  5. Steinar Moum

    Kabel: MiniDin 8<->9 Pins Dsub

    Steinar Moum, Sep 2, 2003, in forum: Apple
    Replies:
    1
    Views:
    216
    Steinar Moum
    Sep 2, 2003
Loading...

Share This Page