• Topic ID: id_17423138
  • Version: 1.0
  • Date: Aug 23, 2018 11:20:51 PM

Rotating 48VDC PS and Fuse Board Replacement

Prerequisites

Overview

This procedure defines the steps necessary to replace the gantry rotating side 48V power supply.

1 Power Supply Assembly Removal

Procedure

  1. Remove gantry side covers and disable Axial drive and HVDC from the Service Switch Panel.

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

  2. Rotate the gantry to position the 48V power supply on the right side of the gantry above the service switch panel and lock gantry in position with rotational lock.

    Figure 1. 48V Power Supply Assembly

  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.
    • danger
    • Electrocution hazard
    • High Voltages present.
    • Use proper lockout/tagout procedures before replacing components. See safety menu of Service Document gui for appropriate procedures.
  4. Turn off the gantry 120 VAC switch on the service panel. Power down the console and use LOTO procedures to make sure gantry power is removed.
  5. Remove the gantry top covers and front cover.

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

  6. Disconnect the AC input cables from the terminal strip on the front of the power supply.
  7. Remove the 8 mounting screws attaching the power supply assembly to the cast frame and slide the supply out the front of the gantry.

2 Power Supply Assembly Installation

Procedure

  1. Slide the new power supply assembly in from the front of the gantry.
  2. Install the 8 - M4 screws to attach the supply to the cast frame.

    Figure 2. Mount Hole Locations

    • warning
    • Equipment damage possible
    • loose components can come off if not secured properly
    • failure to follow the instructions in this procedure as defined can cause a component to become loose later.
  3. Torque the 6 - M4 screws near the fuse board (See Figure 2) to the following value:
  4. The 2 deep recessed screws, identified in Figure 2, are hard to get to if you do not have a 3 inch long 3 mm driver bit. Either of the following 2 steps can be used to tighten these 2 screws.
    1. Preferred method: Using a 3 mm (3 inch long) driver bit, torque the 2 deep recessed screws to:
    2. Alternate Method: Using a 3 mm hex wrench seat the screws then continue to turn 1/4 turn to apply sufficient torque. Do not over tighten. Use the approximate force applied to torque the other 6 screws as a guide to the force limit for these 2 screws. If either screw strips out the threads of the power supply you will need to order a new supply. Do not allow operation of the system with stripped mounting screws.
      note:

      Do NOT use this alternate torque method anywhere else in the system unless specifically defined by the service procedure.

  5. Reconnect input and output cabling to power supply assembly as removed. Install Ty-wraps in all locations removed during supply removal. Reconnect cable clamps removed previously.
  6. Torque the 120V input power connections (2 screws) to the following value:
  7. Restore power to the system and gantry per LOTO procedures.

3 Finalization

Procedure

  1. Check power supply output levels per 48 Volt Power Supply Checks.
  2. Perform a Gantry Rotation Safety Check.
  3. Check Gantry Balance to verify gantry is still balanced.
  4. Run DASToolsAuto Test to verify that no noise is introduced by the new supply.
  5. Turn OFF the Axial Drive, HVDC and 120 VAC switches on the gantry’s Service Switch Panel.
  6. Install the gantry front, top and left side covers.

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

  7. 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.
  8. Install the gantry right side cover.