• Topic ID: id_16157451
  • Version: 2.0
  • Date: Apr 9, 2020 8:42:04 PM

GDAS Power Supply Adjustment

Prerequisites

Overview

This procedure describes the method for adjusting the GDAS (Global Data Acquisition System) power supplies. It is important to follow the detailed procedure to ensure that proper current load is achieved.

1 DAS Power Supplies Reference Points

To aid in this adjustment, monitor the test points on the center backplane with a meter. However, the test point voltage values will differ from those displayed in “Aux Channel Test” in DAStools, which reports actual voltages at the DCB. The supply voltages are correctly set when the display in DAStools Aux Channel Test reads the specified values. Refer to Table 5, it identifies the test point to use as a reference for checking each supply (digital or analog power supply chassis as stated in the description).

2 Voltage Adjustment Requirements

Procedure

  1. The GDAS has a digital power supply chassis and an analog power supply chassis. The 24V and 12V supplies are not field adjustable. If they do not meet the specifications for output defined in Table 5, you will need to replace the power supply chassis containing the bad supply.
    note:

    For GDAS there is no 12V supply to the DAS. The center backplane is common to both MDAS and GDAS and will still have a 12V test point. This test point will read zero volts on a GDAS system.

3 Adjustment Procedures for 5V Supplies

Each of these power supplies is a single source and needs to be adjusted under full load. This procedure applies to both types of power supplies, Including Astec) used on GDAS systems.

Procedure

  1. Remove the gantry right side and the top cover.
    • danger
    • CRUSH HAZARD.
    • UNEXPECTED GANTRY ROTATION CAN CAUSE SERIOUS INJURY.
    • Never service the gantry with the axial drive enabled.
  2. Turn off Axial Drive Enable and rotate the gantry for easy access to the DAS power supplies. The Analog power supply chassis is mounted behind the left DAS chassis. The Digital power supply chassis is mounted behind the right DAS chassis.
  3. Engage the gantry rotational lock.
  4. From the Common Service Desktop at the console start the DAStools diagnostic and run the Aux Channels test to read the power supply voltages at the DCB. Use the voltage levels reported by this tool for adjustment to the specifications in Table 5.
  5. After looking at the Aux Channel report, you can connect a DVM to the test points labeled in Table 5 for a local reference when adjusting the pot. Note the difference between the test point value and the Aux Channel report and adjust accordingly.
  6. Continue to adjust and rerun Aux Channel test until the Aux channel report for the supply matches specifications.

4 Finalization

Procedure

  1. Disengage the gantry rotational lock and re-enable the Axial Drive.
  2. Replace the covers.
  3. Perform test scans and verify proper system operation.