• Discovery MR750 3.0T System Service Methods
  • 5690009-2EN Revision 4
  • Object ID: 00000018WIA30F8D030GYZ
  • Topic ID: id_12373940 Version: 1.14
  • Date: Oct 11, 2021 3:47:42 PM

DTRSW and Preamp Combiner Replacement

Prerequisites

Table 1. Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1Not Applicable30 minutes30 minutes
Table 2. Tools and test equipment
ItemQuantityEffectivityPart numberManufacturer
Non-magnetic Phillips Screwdriver1---
Basic Hand Tool Set1---
Table 3. Replacement parts
ItemQuantityEffectivityPart numberManufacturer
Dual Drive Transmit Receive Switch1-

See FRU Manual

-
Preamp Combiner1-

See FRU Manual

-
Table 4. Safety

About this task

Overview

This procedure applies to MR750 systems with a dual drive RF amplifier. For MR750 systems with a single drive RF amplifier, refer to Body Hybrid Replacement .

This procedure includes the following FRU replacement procedures:

  • Dual drive transmit receive switch (DTRSW). Note that the DTRSW for MR750 is different from other products like MR750w and Signa Architect. Refer to the FRU Manual for the correct part number.

  • Preamp combiner

Topic ID: id_SL1962441-1130473

Removing DTRSW or Preamp Combiner

Procedure

  1. Perform LOTO on the PDM-RF power for the system. See the MR Service Safety Manual, PN 5452735.
  2. Remove the left lower cover and the left upper cover. See Side Cover Removal and Installation.
  3. Disconnect the cables connected to the DTRSW, as follows:

    • If you replace the DTRSW, remove all cables.

    • If you replace the preamp combiner, remove cables from J9, J10, J11, and the Hart ID connector on preamp combiner.

    Figure 1. DTRSW Cable Connections (RRx)
    Item Description Item Description
    1J9 – Combiner LNA 1 input7J10 – Combiner LNA 2 input
    2J9 – HART ID for preamp/combiner8J6 – Body LNA 2 to preamp ASM
    3J11 – Combiner LNA output9J3 – Body coil 2
    4J1 – RF input 110J7/J8 – BD bias
    5J2 – RF input 211J2 – Body coil 1
    6J20 – HART ID for MR750 DTRSW12J5 – Body LNA 1 to preamp ASM
  4. To replace a defective preamp combiner, remove the 4 screws attaching it to the DTRSW.
    Figure 2. Screws Attaching Preamp Combiner to MR750 DTRSW
  5. If you are replacing the DTRSW, remove the preamp combiner first as shown in Step 4. Remove the 4 screws holding the DTRSW to the outside of the magnet.
    Figure 3. Screws Holding MR750 DTRSW
  6. If you are replacing the DTRSW, remove the preamp combiner and reinstall it on the new DTRSW.
  7. While carrying any module out of the magnet room, stay as far away from the magnet as possible.
Topic ID: id_SL1962448-1130473

Installing DTRSW or Preamp Combiner

Procedure

  1. While carrying any module into the magnet room, stay as far away from the magnet as possible.
  2. Secure the module, as follows:

    • For the DTRSW, secure the module to the magnet by tightening the four screws.

    • For the preamp combiner, secure the module to the DTRSW by tightening the four nuts.

  3. Connect all cables that were previously removed. See Figure 1.
Topic ID: id_15201878

Finalization

Procedure

  1. Replace the side covers.
  2. Remove LOTO from the PDM-RF power for the system. See MR Service Safety Manual, PN 5452735.
  3. Perform TR Dynamic Disable Calibration.
  4. If hardware was replaced, perform System gain calibration for body.
  5. Perform Dual Drive Quadrature Tool.
  6. Perform a body SNR test.
  7. Perform SaveInfo to save new calibration values.
  8. Complete a body and head test scan to make sure the system is functional.