Power Board Replacement - Merc40

Prerequisites

Table 5. Safety

CRUSH HAZARD.
UNEXPECTED GANTRY ROTATION CAN CAUSE SERIOUS INJURY.
Never service the gantry with the axial drive enabled. Use the gantry rotation lock to lock out gantry rotation. See safety menu of Service Document gui for appropriate procedures.

Table 6. Required conditions
Condition	Reference	Effectivity
Only trained service personnel should service the GE CT Scanner.	-	-
Static strap and monitor must be used when working inside the detector.	-	-

Overview

This procedure defines the necessary steps to Remove and Install the Power Board.

Move table to home position, fully out and down.
Remove right side gantry cover.

Refer to Parts Replacement → Gantry → Enclosure → (Cover Removal Procedure).
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.
Turn OFF the Axial Drive and HVDC switches on the gantry’s Service Switch Panel.
Position the detector at 12 o'clock and lock gantry rotation.
Turn OFF the 120 VAC switch on the gantry’s Service Switch Panel.
Remove the gantry left side cover, top covers and front cover.

Cover the Tube Collimator port to protect it against dropped tools or screws. (Cloth or any other available item)
Remove the Air Plenum as shown in Detector Air Plenum Removal/Installation.
Remove 12 screws holding the power board to the backplane of DAS.

Figure 1. Screws of Power Board

To prevent damage to connectors pins on the power board, do not disconnect the 2 connectors on the power board singly.

Hold the power board as shown in illustration below, and carefully and slowly wiggle or rock the power board, then disconnect the 2 connectors on the power board from the backplane at a time.

Figure 2. Power Board Disconnection
Pull out the power board from the guide pins on the backplane.

Figure 3. Guide Pins

Install the new power board along the guide pins.
Push the backside of connectors on the power board forward slightly, and connect them to the backplane.

Figure 4. Power Board Connection
Tighten the 12 screws to fix the power board to the backplane.
Install the Air Plenum as shown in Detector Air Plenum Removal/Installation.
Remove the cloth or any other item from the tube collimator port.

Make sure the Axial Drive, HVDC and 120 VAC switches on the gantry’s Service Switch Panel are OFF.
Release the gantry rotational lock and install gantry covers, all except the right side cover.

Refer to Replacement → Gantry → Enclosure → (Cover Removal Procedures).
Turn on the 120 VAC, HVDC and Axial drive service switches.
Install gantry right side cover.

Perform a [Quality Assurance Test] from the [Functional Checks] menu of the service manual to ensure system operation.