11. PROCEDURE 3A. MAIN BOARD 024-350-300-094 REPLACEMENT
Refer to Drawing 3A in Section 10, central unit parts list for board location.
Mark all connections before removing, to identify location for
1. Turn system power off.
2. Remove the central unit lid.
3. See Procedure 2A for main board layout of data and system EPROMs. Use an
EPROM puller to remove EPROM, be careful not to bend or break the legs on
the EPROM. Remove data and system EPROMs from old board and place in
4. Remove timer board and 90° adapter #20 and #21 from old board and place in
new board, see Drawing 3A for timer board location.
5. Disconnect ribbon cable #7 and #8, see Drawing 3A.
6. Disconnect connection X1:1 and X1:3, see Drawing 3A.
Take care not to damage boards, when removing and
7. Remove the 9 main board mounting screws.
8. Take notice of the orientation of the main board in the central unit. Remove
main board and place in the packing material that the replacement main board
9. Carefully insert the new main board in place, see Drawing 3B.
10. Insert the main board mounting screws and washers.
11. Connect X1:1, X1:3 and ribbon cables #7 and #8, see Drawing 3A.
12. Inspect the gasket for nicks, cuts, or damages. Refer to 031-300-340-003 DS
350 Central Unit Gasket Recommendations and 031-300-340-002 Central Unit
Cover Installation and Tightening Procedure.