Discovery MR750 3.0T System Service Methods
5690009-2EN Revision 4
Object ID: 00000018WIA30B5A030GYZ
Topic ID: id_12374694 Version: 1.7
Date: Jan 24, 2020 12:23:28 PM

Table/dock connector and Touch-n-Go (TnG) cable replacement

Prerequisites

Table 1. Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
2	Not Applicable	90 minutes	Not Applicable

Table 2. Tools and test equipment
Item	Quantity	Effectivity	Part number	Manufacturer
Cable Ties	As needed	-	-	-
Flat-Blade Screwdrivers, small and medium	1 each	-	-	-
3.0T MCRv Tool	1	-	5182417-2	-
1.5T MCRv Tool	1	-	5182417	-
Nonmagnetic Tool Kit	1	-	5112581	-

Table 3. Consumables
Item	Quantity	Effectivity	Part number	Manufacturer
Loctite® 242 Threadlocker (medium strength, 0.5 cc tube)	1 tube	-	See FRU manual.	-

Table 4. Replacement parts
Item	Quantity	Effectivity	Part number	Manufacturer
Self-Locking Cable Tie	5	-	46-208758P5	-
Table Side Dock Connector (includes table cable & ODU harness)	1	-	See FRU manual.	-
Dock Side Dock Connector (includes cable & ODU harness to reroute box)	1	-	See FRU manual.	-
Bumper Touch and Go Cable Assembly	1	-	See FRU manual.	-

Table 5. Safety

DANGER

ELECTROCUTION HAZARD!

HIGH VOLTAGE PRESENT.

USE PROPER LOCK-OUT / TAG-OUT PROCEDURES BEFORE servicing and/or maintaining THE DOCK.

Warning

POSSIBLE PERSONAL INJURY!

THE DOCK CONNECTOR REPLACEMENT PROCEDURE REQUIRES MOVEMENT OF FERROUS MATERIAL IN CLOSE PROXIMITY TO THE MAGNET.

two Field engineers are required at all times.

Warning

Personal injury and equipment damage

If the magnet is energized, tools and loose materials that contain ferrous material will be strongly attracted to the magnet and may become dangerous projectiles.

When servicing any magnetic equipment, it is critically important that the service engineer consciously plan the path to be taken when moving highly ferrous devices within the magnet environment. The path should be as far from the magnet as practical and avoid high flux-density fields.

Movement of ferrous material in the magnet room must follow the GE service procedure for that device.
When exiting, move away from the magnet in the most direct manner possible. Except when moving ferrous material to and from its native location on or near the magnet, the static magnetic field in any portion of the service path shall not exceed 200 Gauss.
Two (2) MR safety trained personnel must be present at all times when servicing highly ferrous devices in the areas of magnetic fields.
When planning a service path, it is critical that the path be clear and sufficiently wide. Make sure that there are no trip hazards, obstacles, clutter, slippery surfaces, or other items even partially restricting the path. If there are portable obstacles in a path, remove them from the area and replace them after the service action is completed. It is required to walk the path prior to beginning service to ensure that there is sufficient space through which to pass for yourself and the object being serviced.

About this task

Overview

The patient table and dock each contain a connector plate that passes data from the table to the Reroute Box, then to the RF Hub. The patient table houses two port connectors (P3 and P4) at the rear of the cradle. Signals flow from the patient table to the system by way of several cables with connecting points. When the patient table and dock are connected, data travels between two types of connectors, coax for RF signal and pin/socket for control. The most important connection is where the patient table connects to the magnet via the dock. This document describes replacing each side of this connection.

Topic ID: id_SL2050554-1061609

Table connector

Topic ID: id_SL2054421-1061609

Table connector plate removal

Procedure

Undock the Patient Table and remove it from the Magnet Room.
Fasten the Upper Base Cover in the up position, and remove the Lower Base Cover. Refer to Patient Table Upper and Lower Base Cover Removal.
Remove the Front Base Cover.
Lower the table Lock Safety Bar (shown below), lower the table, and ensure weight is resting on the lock bar.

Figure 1. Table lock safety bar
Remove the two screws on each side of the Table Interface Panel (TIP). This allows movement of the panel back allowing access to the cable connector screws.

Figure 2. Table interface panel screws
Remove all cable connections from the front side of the TIP shown below.

Figure 3. Front side cable connections

Notice

Take care when disconnecting the black cable connectors since they use lightweight aluminum screws that can be easily stripped.

Use small and medium flat-blade screwdrivers to remove the cable connector screws.

Pull the cables through both sides of the table support holes shown below.

Figure 5. Cable path through table support holes

Notice

There are two groups of cables, left and right, behind the Connector Plate. Before cutting the cable tie to remove the cables, pay close attention to how the cables are coiled and tied. The coiling allows the cable bundle to expand and contract as the Table Frame Connector assembly moves forward (docks) and backward (undocks). When installing the replacement assembly, it is imperative the cables are coiled according to specification for the assembly to move forward and backward on its track.

Cut the cable tie holding the bundled cables together behind the Connector Plate.

To remove the table Connector Plate, follow these steps:
1. Use a flat-blade screwdriver to remove the four screws from the face of the Connector Plate.
  
  Figure 7. Location of screws on the front of the connector plate
2. To remove the plate and cables, guide the Connector Plate forward with one hand while feeding the cables through the opening in the frame assembly as shown.
  
  Figure 8. Top View of Table Frame Assembly

Topic ID: id_SL2054434-1061609

Table connector plate replacement

Procedure

Feed the cables through the opening in the frame assembly, and then lay them out to one side while holding the Connector Plate in place at the front of the frame assembly.
Replace the four slotted screws on the face of the plate.
Separate cables by port sides and install, without fully tightening, three cable ties. Tie wrap ends of the cable groupings on the left side, right side, and front of the connector plate. (Keep cable for interlock behind the cable bundles.)

Figure 9. Cable separation with ties

Notice

Be careful when reconnecting the large black cable connectors. They use small aluminum mounting screws that can be easily stripped.

To route the cables through the table support holes, take the right side bundle of cables and create a single loop, feed the cables through the right side table support hole, and reconnect them to the front side of the TIP. (Make sure the Table Top Interlock table is behind cable loop.) Repeat the process for the left side bundle of cables. (See Figure 5.)

Note: Wait to cable tie the cable bundles until the slack is checked on each coiled bundle.

Replace both screws on each side of the TIP.
Once the connection is made, secure the cable ties (as shown) for proper strain relief of the cables. Trim cable ties as necessary.

Figure 10. Secure cables with cable ties
Lift the cable loops and install the cable ties as shown in Figure 6. Trim as required.
Carefully push the frame assembly into its retracted position while ensuring the coiled cable bundles maintain their loop without interference. Repeat the process of manually moving the frame assembly forward and back to confirm integrity of coiled cable bundles.

Figure 11. Cable bundles in docked and undocked frame assembly position
Raise the table, then move the table Lock Safety Bar (shown in Figure 1) to the up position.
Replace the front, upper and lower base covers.
Move the table back into the Magnet Room and redock the patient table.
Proceed to #id_15262008__SL2090374-1061609.

Topic ID: id_SL2050555-1061609

Dock connector

Topic ID: id_SL3518623-1061609

Dock removal from magnet room

Procedure

Follow instructions in Dock Removal and Reinstallation to remove the dock from the Magnet Room.
Proceed to the next section.

Topic ID: id_SL2050556-1061609

Dock connector plate removal

Procedure

Notice

Be sure to disconnect the switch connector before removing the dock cover.

When the dock is outside of the Magnet Room, use a 3/4-inch wrench to remove four bolts (two on each side), and unfasten the dock cover from the dock base.

Turn the dock cover upside down as shown, being careful not to scratch the top of the cover, and set it on a protective cloth on the floor.

Figure 13. View of upside down dock cover
Using a 5/16-inch nut driver, remove the four nuts from the front of the Connector Plate.

Figure 14. Top view of dock
Leave the Dock Connector Spacers attached to the dock.

Figure 15. Dock connector spacers intact
Route the cables through the opening inside the dock cover and remove the dock Connector Plate assembly.

Topic ID: id_SL2050561-1061609

Dock connector plate replacement

Procedure

Route the four large black connectors (two at a time) through the opening in the dock cover, followed by the two large white connectors, and the remaining two gray cables.

Figure 16. Dock connector cables
Reattach the dock Connector Plate to the connector spacers on the front of the dock, paying attention to the correct orientation of the plate.

Note: Hold the dock spacer screws in place while tightening the dock Connector Plate to the connector spacers. Apply torque to the driver only, not over torquing to prevent damage to the M4 Dock Connector Bolts as they can easily shear. (See Figure 14).
Carefully turn the dock cover right side up, reconnect the dock switch connector, and place the dock back on the dock base. Reattach the dock bolts. (See Figure 12).

Topic ID: id_SL3518626-1061609

Dock installation

Procedure

Follow instructions in Dock Removal and Installation to install the dock.
Proceed to the next step.

Topic ID: id_SL3428729-1061609

Replacing the Touch-n-Go (TnG) harness assembly

Procedure

Undock the patient table and remove it from the Magnet Room.
Remove the upper bellows, lower base cover, front upper right and front base covers as detailed in Patient Table Upper Bellows and Lower Base Side Cover Removal.
Lower the table Lock Safety Bar, and lower the table to ensure weight is resting on the lock bar.

Figure 17. Table lock safety bar
Locate the TnG Cable assembly. To disconnect it from the switch, use your fingernail or a small flat-blade screwdriver to depress the latch on the cable side connector (as shown below), and separate the cable assembly from the TnG pigtail cable connector.

Figure 18. TnG cable with switch connector
If necessary, cut the TnG cable tie wrap.

Figure 19. Touch and Go Cable Tie Wrap
At the Connector Mounting Plate, disconnect the cable and replace it.

Figure 20. Connector mounting plate
To reassemble, reverse Step 1 through Step 6.

Topic ID: id_15262008

Finalization

Procedure

Check the operation of the Touch and Go cable assembly by establishing a landmark and scan, or by executing the TnG found on the SRI Functional Diagnostics menu.