Board And Module Disassembly; Control/Display Unit Removal; Altitude Decoder Board Removal; Interface Board Removal - Garmin GPS 155 Repair Manual

3.2

BOARD AND MODULE DISASSEMBLY

3.2.1 Control/Display Unit (011-00127-00) Removal
1. Remove the covers as described above.
2. Disconnect the battery pack wiring harness from the 3-pin locking connector (J800) on the main board
(see figures 5 and 12).
3. Remove the power/dimmer control knob and shaft (430-00010-00) by loosening the M3 x 3mm set screw (211-
00025-00) on the coupling sleeve (125-00021-00). (NOTE: On some early versions of the GPS 155, the shaft
extension is connected directly to the power/dimmer switch without an in-line coupler. The control knob is
glued to this one piece extension and cannot be removed. If you are replacing the CDU on one of these units,
you will need to order a replacement control knob and coupling sleeve as well.)
4. Remove the four M3 x 5mm flat head screws (211-00024-00) which attach the CDU to the chassis and the battery
pack.
5. Carefully remove the CDU from the chassis, pulling the assembly away from the two Main Board connectors
(J100 and J102) and the power/dimmer switch.
3.2.2 Altitude Decoder Board (012-00090-00) Removal
1. Remove the covers as described in Section 3.1.
2. Disconnect the battery pack wiring harness from the 3-pin connector (J800) on the Main Board
(see Figures 5 and 12).
3. Remove the two #4-40 standoffs (211-63234-08) which hold the 26-pin DSUB connector to the chassis.
4. Carefully pull the Altitude Decoder Board toward the front of the unit approximately 1/4" until the 26-pin DSUB
connector is clear of its cutout on the chassis. Lift the Altitude Decoder Board away from the Main Board and
chassis.
5. Remove the ribbon cable connector (J701) from the Altitude Decoder Board.
3.2.3 Interface Board (012-00031-01) Removal
1. Remove the covers as described in Section 3.1.
2. Remove the Control/Display Unit as described in Section 3.2.1.
3. Remove the Altitude Decoder Board as described in Section 3.2.2.
4. Remove the four M1.7 x 5mm flat head screws (211-56201-05) retaining the data card race (145-00056-00) and
Interface Board.
5. Slip the data card race off the Interface Board connector (J700).
6. Carefully pull the Interface Board upward out of the unit, disengaging it from the Main Board
Connector (J107).
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