• Discovery MR750 3.0T System Service Methods
  • 5690009-2EN Revision 4
  • Object ID: 00000018WIA30C20130GYZ
  • Topic ID: id_12373798 Version: 1.11
  • Date: Dec 29, 2021 8:34:19 AM

Patient Table Up Limit Replacements

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable30-120 minutes15-30 minutes
Table 2. Tools and test equipment
ItemQuantityEffectivityPart numberManufacturer
5/16 hex bit (3/8 drive)1---
Non-ferrous Tool Kit1-

5112581

-
Torque Wrench, 8-50 N m Adjustable, non-magnetic1-

5534134 or 5534134-2

-
Table 3. Consumables
ItemQuantityEffectivityPart numberManufacturer
Loctite 242As needed-

See FRU Manual

-
Table 4. Replacement parts
ItemQuantityEffectivityPart numberManufacturer
Up Sensor Cable1-

See FRU Manual

-
Up Sensor Cable Tubing1-

See FRU Manual

-
Up Sensor Top Bracket1-

See FRU Manual

-
Up Sensor Cable1Curved table

See FRU Manual

-
Up Sensor Cable Tubing1Curved table

See FRU Manual

-
Up Sensor Top Bracket1Curved table

See FRU Manual

-

About this task

Overview

The patient table up limit switch components are used to set the hydraulic cylinder upper limit. This procedure explains how to replace the patient table up limit switch components.

There are two possible configurations for the table up limit – cable or hook (switch). Follow the instructions for the type of table you are servicing.

The up limit switch mounting bracket for an electrical table requires two persons and the timing varies depending on whether the cradle is removed or not.

See each procedure for specific timing and number of required persons.

Topic ID: id_SL3858297-1062907

Up Sensor Cable and Tubing Replacement (Curved Table Only)

About this task

Required Persons: 1. Procedure Timing: 30 minutes.

Procedure

  1. Undock the patient table and remove it from the magnet room.
  2. Remove the right upper bellows and right lower base side cover, and the front base cover. See Patient Table Upper Bellows and Lower Base Side Cover Removal.
  3. Raise the table to its maximum height.
  4. Lower the table lock safety bar.
    Figure 1. Table Lock Safety Bar
  5. Lower the table and verify that all of the table top's weight is resting on the safety bar.
  6. Remove the hair pin and retaining pin securing the bottom end of the cable to the bell crank.
    Figure 2. Pin and Hair Pin
  7. If you are only replacing the up sensor cable tubing, follow these steps:
    1. Slide the old tubing off and slide the new tubing on.
    2. Fasten the end of the cable to the bell crank, and secure the retaining pin with the hair pin. (See Figure 2)
    3. Proceed to Step 16.
  8. Remove the clamp securing the cable to the up sensor top bracket.
    Figure 3. Table Up Limit Cable Replacement
  9. Remove the retaining ring and washer securing the end of the cable to the up limit pin on the bracket.
  10. Install the new up sensor cable and attach it to the up limit pin.
  11. Fasten the other end of the cable to the bell crank and secure the retaining pin with the hair pin. (See Figure 2)
  12. Attach the clamp securing the cable to the bracket.
  13. Adjust the table up limit cable length to provide enough slack so that when the cylinder is fully raised in the next step, the cable is not stretched and damaged.
  14. Fully raise the cylinder.
  15. Adjust the table up limit cable so that the plunger can move 1 to 2 mm when the hydraulic cylinder is fully extended.

    If the cable is too loose, the plunger will not engage the dock switch fully and the system will not recognize that the table is fully up.

    If the cable is too tight, the cable may break.

    Figure 4. Table Dock Push Button
  16. If there are no additional replacements, proceed to Finalization. Otherwise, continue with the appropriate section below.
Topic ID: id_SL3858679-1062907

Up Sensor Top Bracket Replacement (Curved Table Only)

About this task

Required Persons: 2. Procedure Timing: 90 minutes.

Procedure

  1. Undock the patient table and remove it from the magnet room.
  2. Remove the right upper bellows and right lower base side cover, and the front base cover. See Patient Table Upper Bellows and Lower Base Side Cover Removal.
  3. Raise the table to its maximum height.
  4. Lower the table lock safety bar.
    Figure 5. Table Lock Safety Bar
  5. Lower the table and verify that all of the table top's weight is resting on the safety bar.
  6. Release the cradle and manually slide the cradle forward and either:

    • Have another person hold the cradle end up so you have access to the table top height adjustment screw.

      or

    • Remove the cradle completely.

    See Removing Cradle Assembly

  7. Use a flat head screwdriver to remove the cover plug from the table top height adjustment screw.
  8. Use needle-nose pliers to remove the e-clip from the end of the table top height adjustment screw.
    Note:

    Place a piece of tape over part of the e-clip before removing it so that the e-clip does not become lost during removal. Remove the tape after removing the e-clip.

  9. If the cradle was not removed, slide the cradle back onto the table.
  10. While moving the table down rod to the rear of the table, pull down on the hydraulic shaft. Stop when the hydraulic shaft is low enough to access the top of the up sensor top bracket.
    Figure 6. Hydraulic Shaft
  11. Remove the two screws (at the top of the hydraulic cylinder) attaching the up sensor top bracket to the hydraulic cylinder. Replace the up sensor top bracket.
    Note:

    The top can be rotated, which also changes the table height. Make sure to return the top back to its original position.

  12. Carefully raise the table. The hydraulic cylinder must fit through the hole in the table. Check that the hydraulic cylinder is completely within the hole and that the table height adjustment is accessible.
  13. If the cradle is still attached to the table, release the cradle, manually slide the cradle forward, and have another person hold the end of the cradle so you have access to the table top height adjustment screw.
  14. Re-attach the e-clip and cover plug.
  15. If the cradle was not removed, slide the cradle back onto the table. Otherwise, reinstall the cradle.
  16. Fully raise the cylinder.
  17. Adjust the table up limit cable so that the plunger can move 1 to 2 mm when the hydraulic cylinder is fully extended. See Figure 4.

    If the cable is too loose, the plunger will not engage the dock switch fully and the system will not recognize that the table is fully up.

    If the cable is too tight, the cable may break.

  18. If there are no additional replacements, proceed to Finalization. Otherwise, continue with the appropriate section below.
Topic ID: id_15241157

Finalization

Procedure

  1. Verify proper operation of the table.
    1. Raise the table lock safety bar.
    2. Dock the table.
    3. Verify proper up/down table motion.
    4. When the table is in a fully raised position, verify that the cradle and LPCA can be advanced normally into the bore.
    5. Verify that raising the table to its full height results in the LPCA automatically driving out to engage the cradle.
    6. Verify that lowering the table results in automatic retraction of the LPCA into the bridge.
    7. Verify normal cradle and LPCA motion from the home position to end of travel on the bridge using enclosure In Fast and Out Fast buttons at the operator console.
  2. Replace the upper bellows and lower base covers, and the front base cover.