TM 11-6625-2735-14-1
4. Remove two thread-forming screws nearest the Fan
2. Disconnect one ribbon-cable from the rear of the
Motor circuit-board, that hold the fan motor mount to the
475 DM 43 or DM 40 Main circuit-board and guide the plug
main chassis.
through a slotted opening in the main circuit-board
chassis.
5. Remove the fan motor and Fan Motor circuit-board
as a unit.
3. Unsolder five-wires from the power transformer and
confirm each wire color with its location in the following
list.
To install the Fan Motor circuit-board, reverse the
removal procedure.
a. Wire to terminal 10 is white with a brown stripe.
b. Wire to terminal 10A is white with a red stripe.
Inverter Board Removal (Option 7 only). Remove the
board as follows:
1. Remove the Vertical Output circuit-board shield (if
installed).
2. Unsolder five wires from the power-transformer
terminals and confirm each wire color with its location in
the following list.
a. Wire to terminal 10 is white with a brown stripe.
b. Wire to terminal 10A is white with a red stripe.
c. Wire to terminal 11 is white with a gray stripe.
d. Wire to terminal 12A is white with an orange stripe.
e. Wire to terminal 12 is white with a yellow stripe.
c. Wire to terminal 11 is white with an orange stripe.
d. Wire to terminal 12A is white with a yellow stripe.
e. Wire to terminal 12 is white with a green stripe.
4. Remove two screws from the Power Supply board
chassis (one screw each at the front and rear of the Power
Supply board chassis near the top of the 475 main
chassis). Remove one remaining screw from the main
chassis to the power supply chassis (accessible through
the space along the bottom of power transformer). A long
Phillips screwdriver is necessary to remove all three
screws.
3. Remove two screws from the inverter chassis (one
5. Remove the power supply chassis from the instru-
screw at the front and one at the rear of the inverter
ment, using care to prevent damage to interconnecting
chassis, near the top of the instrument main chassis).
wires that pass through the hole in the main chassis.
Remove one remaining screw from the main chassis to the
inverter chassis, accessible through the space along the
bottom of the power transformer. A long Phillips screw-
6. Remove a piece of tape from the insulation-wrap to
driver is necessary to remove all three screws.
gain access to the board components.
4. Remove the Inverter chassis from the instrument,
7. Remove the two screws holding the Power Supply
using care to prevent damage to interconnecting wires
circuit-board to the power supply chassis.
that pass through the hole in the main chassis.
8. Remove three Keps nuts and a plastic bar that hold a
5. Remove the screws holding the Inverter circuit-
transistor and two integrated circuits to the power supply
board to the Inverter chassis.
chassis.
To install the lnverter circuit-board, reverse the
9. Unsolder two ribbon-cables, noting the color codes
removal procedure.
and wire positions. If board replacement is intended,
connect the wires to the new board.
Power Supply Board Removal (475 DM 43 and DM 40
only). Remove the board as follows:
1. Remove the Vertical Output circuit-board shield (if
To install the Power Supply circuit-board, reverse the
installed).
removal procedure.
4-27
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