M_Card  Description
                    -------------------------

                                                  Original Rev. 28-OCT-1996
                                               Most Recent Rev. 12-MAR-1997


General Description:

The M_Card is mounted in the camera electronics.  It provides mounting
support and the power supply distribution to the four A_Cards and the one
D_Card.  The two power supply cables from the VME equipment terminate at a
40 pin connector on the M_Card.  The M_Card provides the Analog and Digital
ground connections from the Electronics Box - Dewar to the A_Cards and the
D_Card.  The M_Card does not contain any active electronics but it does
contain filter chokes, bulk power supply filter capacitors, and protection
diodes on the incoming power supply lines.

The four ADC Start Conversion Clock lines run as traces on the M_Card.  All
four of these traces originate at the D_Card socket and one trace
terminates at each A_Card socket.


M_Card Board Structure

The M_Card is a two sided board.  The upper side is divided into analog and
digital ground planes.  The bottom side is divided into power supply
traces, ADC clock traces, and ground planes.

The M_Card is mounted to the Electronics Box via stand off studs.  These
studs provide the ground path from the ground planes on the M_Card to the
Electronics Box.


General Layout of the  M_Card


          +-----------------------------------------------------+
          |                                                     |
          |      +---------------------------------------+      |
          |      |   J1   A_Card   Array Columns   0:63  |      |
          |      +-------------------------------------o-+      |
          |                                                     |
          |      +---------------------------------------+      |
          |      |   J2   A_Card   Array Columns  64:127 |      |
          |      +-------------------------------------o-+      |
          |                                                     |
          |      +---------------------------------------+      |
          |      |   J3   A_Card   Array Columns 128:191 |      |
          |      +-------------------------------------o-+      |
          |                                                     |
          |      +---------------------------------------+      |
          |      |   J4   A_Card   Array Columns 192:255 |      |
          |      +-------------------------------------o-+      |
          |                                                     |
          |      +---------------------------------------+      |
          |      |   J5   D_Card                         |      |
          |      +-------------------------------------o-+      |
          |                                                     |
          |                                                     |
          |                  +-------------------o-+            |
          |                  |  J6 Power Connector |            |
          +------------------+---------------------+------------+





J1:J5   2x70
        2 row 140 pins total

J6      2x20                     Analog and Digital Power coming from the
        2 row 40 pins total      VME Equipment location.




The M_Card will be designed via Mentor key-in COMP and NETS files.