• Topic ID: id_18718218
  • Version: 2.0
  • Date: Feb 4, 2020 1:40:21 AM

GDAS(4/8) Converter Board Replacement

Prerequisites

Overview

Replace suspected faulty board and verify proper operation and Image Quality:

  • Remove covers.

  • Access Converter Boards.

  • Replace part.

  • Verify operation.

  • Assemble gantry.

1 Board Removal

Procedure

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    • Follow ALL Electro-Static Discharge procedures. Always use ESD Wrist Strap and grounding cords. The use of a ground Monitor is suggested.
  1. Position the table to its lowest position.
  2. Remove gantry right side cover.
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    • Always turn OFF the HVDC before the 120 VAC. Turning OFF 120 VAC power before HVDC power can result in equipment damage.
  3. Turn OFF Axial Enable, HVDC, and 120VAC switches on the Service Switch panel.
  4. Lock the gantry in position, using the rotational lock.
  5. Remove appropriate chassis cover.

    • When working in the Right chassis, the fiber-optic cable must first be removed from the Transmit (“TX”) port (see Figure 1).

    • Left and Right chassis have 6 captive screws.

    • Center chassis has 8 captive screws.

    Figure 1. Right DAS Chassis

  6. Slide Converter board out of chassis.
    1. Lift both red ejection tabs and the board will disengage from backplane connection.

      Figure 2. Use Ejector Tabs to Remove Converter Cards From Chassis

    2. Continue sliding board straight out and place into anti-static bag.

2 Board Installation

Procedure

    Notice Image
    • notice
    • Follow ALL Electro-Static Discharge procedures. Always use ESD Wrist Strap and grounding cords. The use of a ground Monitor is suggested.
  1. Remove New Converter Board from anti-static bag.
  2. Align Converter board edges to card guides in Chassis.
  3. Slide the board into the chassis until Red ejector tabs align with the card guides.

    Figure 3. Position Card So That Ejector Tabs Fit Into Channel

  4. Fold the Red tabs over to push board into place. Press in on tabs to fully seat card into the backplane connector-the card should move inward an additional millimeter (approximately).
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    • Card must be fully seated. Failure to fully seat a converter card into DAS backplane may result in the failure of all 128 channels in that converter card.
  5. Turn the Gantry 120V power ON, and verify no failures during power-up self-tests, via DCB LED status or System error log.
  6. Reinstall Converter board chassis cover by first engaging all screws, and then tightening.

    If replacing cards in the right DAS chassis, reconnect the fiber-optic cable to the transmit (TX) port (see Figure 1).

  7. If applications software is up, perform a DAS Reset from the Reset Menu.
  8. Disengage rotational lock.
  9. Turn on Axial and HVDC switches.

3 Finalization

Procedure

  1. Perform a DAS Rest from the Reset Menu.
  2. Depending on the fault, let the board warm-up five (5) minutes to verify it fixed the problem, but at least 1 hour before DASTools, FastCal, or Image Quality scans. A cold board may fail Offset Drift or Pop Noise until it is in normal operating temperature ranges.
  3. Verify proper functionality:
    1. Run at least 10 passes of Scan Data Path Diagnostic from Converter Boards.
    2. Run 1 pass of DAS Tools.
    3. Run FastCal, if less than 5 cards replaced.
    4. Run full FastCal and Phantom Cal, if more than 5 cards replaced or if I/Q fails due to replaced boards.

      Upon running FastCal the first time, Daily IQ check may fail, and can generally be ignored, previded the images look good.

    5. Take 10 I/Q scans of the 48cm phantom.
    6. Verify fault or reason to replace the board now passes.
  4. Reassemble gantry covers.