Discovery MR750 3.0T System Service Methods
5690009-2EN Revision 4
Object ID: 00000018WIA3017D030GYZ
Topic ID: id_12374844 Version: 1.8
Date: Jan 27, 2022 6:50:31 PM

Replacing the cradle latch–curved table

Prerequisites


Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	-	45 minutes	5 minutes


Tools and test equipment
Item	Quantity	Effectivity	Part number	Manufacturer
Non-Ferrous Service Tool Kit	1	-	5112581	-


Replacement parts
Item	Quantity	Effectivity	Part number	Manufacturer
Cradle Latch Cable (cut to 1500 mm)	1	-	Refer to FRU Manual	-
Cradle Latch Housing	1	-	Refer to FRU Manual	-

Table 1. Safety

CAUTION

PINCHED FINGERS

FORWARD MOVEMENT OF CRADLE CAN PINCH FINGER WHILE HOLDING DOWN CRADLE LATCH BLOCK.

MOVE CRADLE FORWARD SLOWLY AND DELIBERATELY UNTIL BOTTOM EDGE OF CRADLE SUFFICIENTLY COVERS TOP OF CRADLE LATCH BLOCK SO THAT YOU CAN REMOVE YOUR FINGER FROM BLOCK.

About this task

Overview

This procedure gives the steps for replacing the cradle latch housing for a 32-channel system or a 16-channel system. The 16-channel system does not allow for the complete removal of the cradle assembly.

Topic ID: id_SL5078255-1167996

Removing the cradle latch housing

Procedure

Undock the patient table and move it out of the magnet room.
Remove the upper bellows and left lower base side cover. See Patient Table Upper Bellows and Lower Base Side Cover Removal.
Raise the table to its maximum height.

Warning

Risk of personal injury

Severe injury can occur if the table is accidentally lowered during maintenance.

When doing maintenance with the table in the Up position, make sure the lock bar is safely engaged.

Lower the table lock safety bar. Lower the table and verify that all its weight is resting on the lock bar.

Hold down the cradle latch block and press the cradle release button at the same time.

Figure 2. Cradle removal
While holding down the cradle latch block and pressing the cradle release button, slide the cradle forward enough so it covers the top area of the latch block. Let go of the cradle latch block and cradle release button.
Push in the right actuator on the table front base.

Figure 3. Table front base
Note:
Pressing the actuator button engages the secondary cradle latch cable and causes the pin stop to move down flush with the table top surface, allowing the cradle to slide forward.

For a 16-channel system, prop up the cradle (see below) or remove it from the patient table to do the desired maintenance.
For a 32-channel system, do one of the following:
1. To remove the cradle from the table:
  1. Use wood blocks (or similar) to prop up the rear of the cradle at least 12 inches above the table top to expose the cable take-up assembly.
  2. Remove screws and cable cover.
    
    Note: These are specific, pure brass screws. Do not mix up or replace with standard brass screws.
  3. Remove the four screws.
  4. Remove the two coil connector screws.
2. To partially remove the cradle from the table:
  1. Slide the cradle forward far enough to clear the cradle guide rail latches at the rear of the table.
  2. Use wood blocks (or similar) to prop up the front of the cradle.
Figure 4. Propping up back of cradle
With the cradle raised, remove the cable covers at the head of the cradle, held by two screws on each side.

Figure 5. Cable cover removal
Untie the knot in the Kevlar cord. A scribe or other tool may be needed to loosen the knot.

Figure 6. Kevlar cord knot and release lever screw
Remove the screw on the bottom of the release lever that holds the Kevlar cord in place.
Pull out the rivet from the side of the release lever, noting that the Kevlar cord is positioned over the rivet.

Figure 7. Release lever rivet
Pull the Kevlar cord through the release lever approximately 6 inches. DO NOT pull the cord out of the release lever completely.

Figure 8. Loosen Kevlar cord
Remove the blocks or other structure used to elevate the cradle. Put the cradle back down so that there is approximately 18 inch (46 cm) overhang at the foot of the table.

Figure 9. Cradle position
Pull the cradle hinge pin out. The cradle hinge pin can only be removed on the left side of the table. Push out the pin on the side using large needle nose pliers.

Figure 10. Remove hinge pin
After the hinge pin is removed, slide the front cradle section out.

Figure 11. Extend cradle section
Remove the rubber latch spring.

Figure 12. Remove latch spring
Remove the two nylon screws.

Figure 13. Remove nylon screws
Unhook the release lever from the release bar. This is accomplished by pulling the release bar, lifting slightly, and away from the lever. The latch assembly will then be free to pull down and remove.

Figure 14. Remove release lever
Note:
There are two Delrin springs installed on each side of the latch assembly. Keep these springs for reuse with the new cradle latch assembly.

Remove the cradle latch assembly from table cradle.
Remove the two plastic screws on top of the removed latch assembly. Then remove the latch blocks. Note the orientation of the angles on the latch blocks for installing the new cradle latch assembly.

Figure 15. Cradle latch disassembly

Topic ID: id_SL5078297-1167996

Installing the cradle latch assembly

Procedure

Install latch blocks and plastic screws into the new latch assembly. Make sure the screws go through the slots on the latch blocks. When assembled properly, the latch blocks will have limited side-to-side movement but will not fall out of the assembly.

Figure 16. New cradle latch assembly
After the new cradle latch assembly is assembled, position the flat side of the latch blocks on the bottom.

Figure 17. Latch block orientation
Install the new cradle latch assembly into the table.

Figure 18. Latch installation
Install nylon screws. See Figure 13.
Install the new release bar with the new latch assembly. This requires lifting the end of the release lever to put the release bar in position on the guide slot as done in Step 20.
Replace the rubber latch spring.

Figure 19. Reinstall latch spring
Put the front cradle plunger in position on the cradle rod.

Figure 20. Cradle rod re-Installation
Slide the cradle back together. Install the hinge rod. A hammer may be required to tap the hinge rod back into position.

Figure 21. Hinge pin installation
Lift the cradle and support it to gain access to the Kevlar cord. See Figure 4.
Insert the rivet back into the release lever, making sure that the Kevlar cord is routed OVER the rivet when it is installed as shown in Figure 7. Pull the Kevlar cord taut without causing the release bar to protrude into the latch housing. The lever should be pushed toward the front of the cradle when doing this step.

Figure 22. Release bar lever
Make sure that the release mechanism is not pulled out, then tighten the screw in the release lever.
Tie a new knot in the Kevlar cord running through the release lever. See Figure 6.
Raise the table lock safety bar.
Install the covers. See Step 10.
Perform Cradle/Table Release Block Adjustment.

Topic ID: id_15197810

Finalization

Make sure that the cradle attaches to the LPCA, and the latch mechanism operates correctly.