TM 11-6625-3145-14
Maintenance: General Information-318/338 Service
Removing the Keyboard
The keyboard is an assembled matrix that fits behind the 318/338’s front panel. Refer to Section 10
, Replaceable
Mechanical Parts
, for a detailed drawing and part numbers. To remove the keyboard, proceed as follows:
1.
Remove the front panel (see
Removing the Front Panel
).
2.
Remove the six screws that hold the keyboard in place.
3.
Gently pull the keyboard assembly toward you and disconnect the 16-pin, square-pin connector located near the
power switch. The LED, resistors, connector, screws, and keycaps are all individually replaceable; the large black
switch assembly is replacable as a unit.
4.
When reassembling the keyboard unit, make sure the 16-conductor connector located under the CRT is correctly
indexed with the notch in the cabinet.
Removing the Power Supply Circuit Boards
The power supply assembly is fastened to the main chassis with four screws and contains the Inverter and Regulator
Power Supply boards. To remove the Power Supply boards, proceed as follows:
1.
Remove the cabinet (see Removing the Cabinet).
WARNING
Dangerous voltage potentials may exist in the power supply circuitry. Allow
approximately three minutes for the power supply filter capacitors to discharge
before proceeding with the next step.
2.
Support the power supply assembly with one hand while removing the four screws that fasten it to the main chassis.
Lift off the power supply assembly. Refer to Figure 6-5.
3.
If the Inverter board is being taken out, remove the screw that retains the cover plate at the top of the power supply
assembly and lift off the plate. If the Regulator board is being taken out, remove the screw that retains the bottom
cover plate.
4.
Remove the four screws that hold the board to the power supply assembly chassis.
5.
If the Inverter board is being removed, disconnect J2, J3, J7, J9, and the jack that connects to the fan from the
board. If the Regulator board is being removed, the same connections must be disconnected from the board.
6.
Lift out the board and replace any defective components.
The power supply transistors and their mounting bolts are insulated from the board. In addition, silicon grease is used to
increase heat transfer capabilities. Reinstall the insulators and replace the silicon grease after working on these
transistors. The grease should be applied to both sides of the mica insulators and should be applied to the bottom sides of
the transistor where it comes in contact with the insulator.
NOTE
After replacing a power transistor, check that the collector is not shorted to ground
before applying power.
6-10
Summary of Contents for 318
Page 119: ...318 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 182: ...338 VERIFICATION AND ADJUSTMENT PROCEDURES ...
Page 253: ...318 ___________________ TROUBLESHOOTING TREES ...
Page 344: ...338 TROUBLESHOOTING TREES ...
Page 517: ...TM 11 6625 3145 14 318 338 4434 923 318 Block Diagram ...
Page 518: ...TM 11 6625 3145 14 318 338 4434 924 338 Block Diagram ...
Page 519: ...TM 11 6625 3145 14 318 338 4434 925 318 Acquisition Module Wiring Diagram ...
Page 520: ...TM 11 6625 3145 14 318 338 4434 926 318 338 Mainframe Wiring Diagram ...
Page 521: ...TM 11 6625 3145 14 318 338 4434 926 338 Acquisition Module Wiring Diagram ...
Page 522: ...TM 11 6625 3145 14 318 338 4434 928 Figure 9 1 318 A01 Input A Board Component Locations ...
Page 526: ...TM 11 6625 3145 14 ...
Page 528: ...TM 11 6625 3145 14 Figure 9 3 318 338 A03 ACQ Control Board Component Locations ...
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Page 542: ...TM 11 6625 3145 14 Figure 9 8 318 338 A10 CRT Board Component Locations ...
Page 544: ...TM 11 6625 3145 14 Figure 9 9 318 338 A11 Inverter Board component Locations ...
Page 546: ...TM 11 6625 3145 14 Figure 9 10 318 338 A12 Regulator Board Component Locations ...
Page 551: ...TM 11 6625 3145 14 Figure 9 12 338 A01 Input A Board Component Locations ...
Page 553: ...TM 11 6625 3145 14 318 338 SERVICE ...
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Page 555: ...PIN 058584 ...