Document X3T9.2/92-129

To:       Membership of X3T9.2

From:     Robert N. Whiteman
          AMP Inc.
          Harrisburg PA

Date:     May 26, 1992

Subject:  P Cable Connector Dimension and Tolerance Study


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     At the May 19th SCSI Working Group, a small group met off-
line to review the dimensions and tolerances of the P cable and
device connector specifications.  The purpose was to insure that
sufficient contact wipe existed at the worst case tolerance
conditions.  In an unusual display of cooperation, the connector
group agreed on the dimensional and tolerance changes in a short
period of time.  The minimum contact wipe will be .021 inches
minimum at worst case tolerance conditions.  Considering standard
statistical manufacturing and assembly conditions the minimum
wipe length will be much longer.

     It was recommended that the changes listed below be made to
the SCSI-3 Rev 4 Parallel Interface standard.  Copies of the
figures are attached, with the drawing changes marked for easy
reference.  Note: Figures are not included with electronic copies
of this document when retrieved from the SCSI BBS.


5.3.2  Shielded Connector Requirements

     Change specification for the shield termination resistance
     from '10' milliohms to '75' milliohms.  This will compensate
     for the bulk resistance present in the various manufacturers
     shielding hardware and connector shells.  75 milliohms is
     also specified in the HIPPI standard.

Figure 3:  Nonshielded Cable connector

     Add the A16 radius dimension (.040 ñ.010 inches) to the
     detail view of the tab contact.  This feature was added as a
     result of the 'connector attribute' motion passed at the
     April '92 meeting.

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                                           Document X3T9.2/92-129

Figure 4:  Shielded Device Connector

     Change B14 dimension to specify the distance from the
     receptacle contact mating point to the front mating flange
     of the connector.  This new dimension to be .130 Min inches.

     Change B16 dimension, screwlock height, from .157 ñ.002 to
     .146 ñ.002 inches.

     Add 'Panel Thickness' note to the B17 dimension on the
     drawing for clarification.

     Change B18 dimension, female #2-56 thread depth in the
     screwlock, from .152 Min to .141 Min inches.

     Add 'Full Thread Depth' note to the B18 dimension on the
     drawing for clarification.

Figure 5:  Shielded Cable Connector

     Change A17 dimension, length of the #2-56 male jackscrew,
     from .147 ñ.006 to .135 ñ.006 inches.

     Add the A19 radius dimension (.040 ñ.010 inches) to the
     detail view of the tab contact.  This feature was added as a
     result of the 'connector attribute' motion passed at the
     April '92 meeting.



Meeting Attendees:

John Assini    AMP
Wayne Davis    AMP
Mike Evans     AMP
Bob Whiteman   AMP
Stan Sharp     Foxconn
Joel Urban     Fujitsu
Tom Kulesza    Honda
Claude Mosely  IBM
Joe Dambach    Molex










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