• Topic ID: task_ax3_sw3_wjb
  • Version: 2.0
  • Date: Dec 10, 2019 2:30:42 AM

Home Flag Sensor Board Assembly Replacement

Prerequisites

Overview

This procedure defines the necessary steps to replace the home flag sensor board or assembly.

1 Preparation

Procedure

  1. Move the table to the home position.
  2. Remove gantry right side cover.

    Refer to Replacement > Gantry > Enclosure > (Cover Removal Procedures).

  3. Stop the rotor of X-ray tube in case of Liquid Bearing Tube before HVDC off. Refer to Liquid Bearing Tube Rotor stop procedure for details.
  4. Turn OFF the Axial Drive and HVDC switches on the gantry’s Service Switch Panel.
  5. Rotate the gantry to place the tube at about the 7o'clock position for easier access to the sensor board.

    Figure 1. Home Flag Position

  6. Turn OFF the 120 VAC switch on the gantry’s Service Switch Panel.
  7. Remove the gantry left side cover, top covers and front cover.

2 Replace Sensor Board or Sensor board assembly

Procedure

  1. Locate the Home Flag Sensor board (Figure 2) near the encoder assembly (Gantry 11 o'clock location).

    Figure 2. Home Flag and Zero Azimuth Board

  2. Disconnect the harness from the sensor board.
  3. If replacing the Sensor board assembly (with bracket) follow this step.

    Using a 5 mm hex wrench remove the M6 screws attaching the bracket assembly to the frame. See Figure 3.

    Figure 3. Home Flag Bracket Assembly

  4. Replace the home flag bracket or the zero azimuth board installing the screws previously removed, tightening 1/4 turn past seated.
  5. Reconnect cable to the sensor board.

3 Restore Gantry

Procedure

  1. Slowly rotate gantry by hand and adjust flag position to pass through the center of the opto-sensor on the sensor board. The home flag is next to the 48V Power supply.
  2. Make sure that the flag is centered in the opto-sensor on the sensor board (Figure 2) and does not make contact with it. Looking at the side view along the side of the 48V PS as shown in Figure 4 can help.

    Figure 4. Flag Position Side View (Example)

  3. If necessary, adjust by loosening the screws and slightly shifting the board. (reposition gantry for easy access along side of the tube as done previously)
  4. Perform the Reset the C-Pulse procedure.
  5. Install the gantry front cover, top covers and left side cover.

    Refer to Replacement > Gantry > Enclosure > (Cover Removal Procedures).

  6. Enable 120 VAC HVDC and Axial Drive service switches from the service switch panel. Press the table drives enable button on the lower right corner of the service switch panel.
  7. Install the gantry right side cover.

4 Finalization

Procedure

  1. Perform a System Scanning Test from the Functional Checks menu of the service manual to ensure system operation.