Discovery MR750w and SIGNA™ Architect T 3.0T System Service Methods
5690002-2EN Revision 4
Object ID: 00000018WIA30722750GYZ
Topic ID: id_2025573 Version: 1.2
Date: Nov 5, 2020 1:37:09 PM

Probe tuning and SNR check troubleshooting

About this task

This section contains illustrations of probe SNR spectra, both incorrectly and correctly tuned, to show what a good spectrum looks like. During tuning or SNR troubleshooting, it may be necessary for a site to back up the original echoloc.dat file. This backup process requires renaming the file; otherwise, it will be overwritten during the tuning calibration. To get more information about the cause of an Auto-Water Suppression (AWS) failure, log the messages generated during the Probe APS. A site may be required to send probe SNR raw data to an expert for review. This section also explains the P raw file location process and how to transfer it.

Topic ID: id_SL1951122-1060211

Example SNR Spectra

About this task

Errors in the probe tuning calibration procedure can introduce changes in the appearance of the resulting probe SNR spectra. This section contains example spectra from a Probe-P SNR protocol using the MRS phantom.

Procedure

Figure 1 shows a correctly tuned spectra. Pay particular attention to the base (left and right) of the NAA (NA) peak; this is the largest peak located at the center of the spectrum.

Figure 1. Correctly Tuned Probe SNR Spectra
Refer to Figure 2 and Figure 3 to view spectra with an uncalibrated tuning parameter (a delta was offset + or - from the correct value by 0.5 units).

Figure 2. Incorrectly Tuned Probe SNR Spectra

Figure 3. Incorrectly Tuned Probe SNR Spectra
To perform probe tuning file and backup, follow these steps:
1. At the MR Service Desktop, click C Shell.
  
  Note: The Shell window can only be launched when the EA3 user is included in the authorized EA3 group. Users not in this EA3 group will not have access to launch the Shell window. If you are not logged on as the proper logon user, log out and then log back on as the correct EA3 user with the authorized permissions.
2. At the prompt, enter the following:
  
  su -
  
  Password: operator
  
  cd /usr/g/caldir Enter
  
  cp echoloc.dat echoloc.bak1 Enter
Note:
It is possible that the customer changed the default password. If you cannot log in, contact the customer for the correct password.
Close the C Shell.

Note:
The echoloc.dat file does not exist for initial software loads.

The actual files that contain the probe calibration values are in the caldir directory as probesfix.dat and probepfix.dat. The unlabeled values are deltax, deltay, and deltaz.

To get more information about the cause of an AWS failure, log the messages generated during the Probe APS.

Topic ID: id_SL1951128-1060211

Directory Creation

Procedure

On the MR Service Desktop, click C Shell.

Note: The Shell window can only be launched when the EA3 user is included in the authorized EA3 group. Users not in this EA3 group will not have access to launch the Shell window. If you are not logged on as the proper logon user, log out and then log back on as the correct EA3 user with the authorized permissions.
Create a directory to hold the log file by entering the following:

cd /usr/g Enter

mkdir probe_data Enter

cd probe_data Enter.
Log in to the MGD AGP and direct the output to a file and to the screen. Use the pipe symbol (|) on the keyboard where indicated below. Local is the lowercase “l” key.
rlogin agp | tee agp_log Enter.
Log in using the user name agp , then press Enter. When prompted, enter the password agpservice and press Enter.

Note:
It is possible that the customer changed the default password. If you cannot log in, contact the customer for the correct password.

At this point logging is running. DO NOT type anything in the AGP window. Watch the AGP messages appear on the screen; everything is logged to the file entered after the tee command (tee agp_log). This file is overwritten each time.
Select the Rx Manager icon.
Run Auto Prescan (APS).

Note:
No data appears in AGP_LX during APS.
Select the Service Desktop Manager icon and use the scroll bar to review the log.
When done, type logout in the AGP window. This disconnects the AGP from the C Shell. A message confirms the logout.
To view the log file created, verify that the current directory is /usr/g/probe_data.
Type more agp_log and press Enter.
Close the C Shell when you are done.
The log file can be sent to the OLC, or e-mailed to whomever the site is working with to resolve any problems.

Topic ID: id_SL1951143-1060211

P Raw Data File Location

About this task

During the troubleshooting process, the site may be required to identify the P raw data files generated when Probe SNR was performed. These files may be helpful in determining a reason for an SNR failure. This portion of the procedure should be performed after running a Probe SNR protocol to facilitate P raw file identification.

Procedure

At the Service Desktop Manager, click C Shell.

Note: The Shell window can only be launched when the EA3 user is included in the authorized EA3 group. Users not in this EA3 group will not have access to launch the Shell window. If you are not logged on as the proper logon user, log out and then log back on as the correct EA3 user with the authorized permissions.
At the prompt, enter the following:

cd /usr/g/mrraw Enter

ls -lt P*| head Enter
The most recent P files are displayed. The most recent P files are displayed on the top of this list. Record the Probe raw data file (P####.7). The size of the P file is ~449584.
Close the C Shell when finished.