• SIGNA MR355 / SIGNA MR360
  • Service Manual
  • 5856356-3EN Revision 5.0
  • Basic Service Documentation. Copyright General Electric Company.
  • Object ID: 00000018WIA30007E20GYZ
  • Topic ID: id_13106832 Version: 3.0
  • Date: Aug 29, 2019 1:36:10 AM

DC Offset Adjustment

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable5 minutesNot Applicable
Table 2. Required conditions
ConditionReferenceEffectivity

No scan in progress. Hit End Exam to end any exam in progress.

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About this task

DC Offsets will need to be run during the initial system calibration, at the time of system upgrade (i.e. EXCITE 2 to EXCITE 3) or if the GP or SGA has been replaced.

Procedure

  1. Go to the Service Desktop and select Calibrations from the Service Browser. See Figure 1.
    Figure 1. Selecting DC Offset Calibration in the Service Browser
  2. Select DC Offset Calibration, then Run for Normal Mode or Run for TRM Zoom Mode. You will need to run both modes if your system is a TwinSpeed.

    Whole and Zoom will run and after completion results will display in the Test Results Box.

    A report of “DC Offset calibration has been completed” signifies that the calibration is done. The calibration should only be run once for each mode (Whole or Zoom).

  3. The calibration values for ACGD are stored in /usr/g/caldir/gram_tune.dat.WHOLE for Whole Body coil (or gram_tune.dat.ZOOM for Zoom coil) file.

    For HFD the values are stored in /usr/g/caldir/gradient_tune.dat.WHOLE or /usr/g/caldir/gradient_tune.dat.ZOOM. (Do not touch the Offset pots on the SGA’s.)

    For HFD-S-Lite the values are stored in /usr/g/caldir/gradient_tune.dat .

    Note:

    The calibration values are relative to the site DC Offsets is run on and can vary greatly from site to site.

  4. Perform TPS Reset or end diagnostics.
  5. Go to grafidy 3

Finalization

No finalization steps.