7.7.2.2 Preliminary Operations/Safety Precautions. Proceed as follows:
 
 

Hazardous voltages are present within the transmitter cabinet. Turn OFF transmitter high voltage power by performing the procedures in paragraph 3.4.1.2 steps 1 through 5c. Take all standard precautions against electric shock. Failure to comply may cause serious injury or death.

1.  Turn OFF transmitter high voltage power and place the transmitter in the maintenance mode by performing the procedures in paragraph 3.4.1.2 steps 1 through 5c.

2. Open and remove right-bay outer door.

3. Remove key from circuit breaker CB1 lock.

Filter Capacitor Bank A9 can hold a lethal charge long after transmitter power has been removed. Discharge Filter Capacitor Bank A9 after transmitter power is off and prior to transmitter maintenance by opening the right-bay inner door while monitoring the charge on VOLTAGE/CURRENT meter M4, at position 6, +280 Vdc power supply. Opening the right-bay inner door releases the filter capacitor bank discharge plunger. Failure to comply may cause serious injury or death.

4. Use key to unlock right-bay inner door and open right-bay inner door.

5. Open and remove center-bay door.

7.7.2.3 Modulator Pulse Assembly UD3A12 Access Procedure. See figure 11-28, sheets 1 and 2, and figure
11-29, sheets 1 and 2 and proceed as follows:
 

1. Perform steps in paragraph 7.7.2.2.

2. Remove A10 in accordance with paragraph 7.6.10.

3. Unscrew two captive screws on front bottom of A12.

4. Press both release knobs at bottom of A12 and slide A12 slowly out of cabinet until braided ground wire connection is exposed on the top left side of A12. Disconnect braided ground wire.

5. Disconnect J3 from P3 on A12 top cover.

6. Slide A12 slowly out of cabinet until stops are engaged and J2 is exposed. Disconnect J2 from P2.

7. Lower the front support at bottom of A12 and lock into position using quick release. See figure 11-28, sheet 1, detail A.

8. Press both release knobs at bottom of A12 and slowly pull A12 out of cabinet until access is gained to terminals A12E7A, A12E7B, A12E8A, and A12E8B.

9. Use grounding stick located in center-bay cabinet to ground out terminals A12E7A, A12E7B,A12E8A, and A12E8B.

The high-voltage leads to terminals A12E7A, A12E7B, A12E8A, and A12E8B will be strained or broken if care is not exercised during Modulator Pulse Assembly A12 removal.

10. Remove high-voltage leads from terminals A12E7A, A12E7B, A12E8A, and A12E8B and note locations to ensure correct replacement.

11. Press both release knobs at bottom of A12 and slowly pull A12 out of cabinet until stops are engaged.

12. Use grounding stick located in center-bay cabinet to ground out terminals A12E1, A12E2, A12E3, A12E4, and A12E10 on rear of A12. See figure 11-21, sheet 2.

13. Loosen captive fasteners from A12 top cover.

14. Slowly tilt the top cover up on its right edge and secure it in an upright position using the top cover support. See figure 11-29, sheet 2, detail A.