• Discovery MR750w and SIGNA™ Architect T 3.0T System Service Methods
  • 5690002-2EN Revision 4
  • Object ID: 00000018WIA3026D630GYZ
  • Topic ID: id_19633147 Version: 2.15
  • Date: Oct 11, 2021 8:57:27 PM

Applying LOTO - RF subsystem (magnet room electronics)

Prerequisites

Personnel requirements
Required personsPreliminary requirementsProcedureFinalization
1-30 minutes-
Tools and test equipment
ItemQuantityPart numberManufacturer
RED Logout Tagout Lock with Each Lock Uniquely Keyed 15451778-
Multi-Locking Device (if multiple service personnel are involved)146-194427P313-
Red Warning LOTO Tag146-194427P322-
Digital Voltmeter (DVM)146-194427P284-
Safety

Before working in any GE Healthcare MR suite or performing any GE Healthcare service procedure, you must:

  • Have read and understood all hazard conditions and safety requirements in the latest revision of the GE Healthcare MR Service Safety Manual (5452735).
  • Have successfully completed all relevant GE Healthcare Environmental Health and Safety (EHS) courses (or for non-GE employees, equivalent workplace training courses).
  • Comply with all site-specific training and workplace safety requirements.

If you have any safety concerns at any time, do not begin work or immediately stop work and move to a safe location. Immediately contact your supervisor or site safety officer for instructions on how to proceed.

About this task

Prior to performing service or maintenance work on the RF (Radio Frequency) Subsystem electronics, Penetration (PEN) Cabinet Panel electronics (such as Patient Handling Power Supply), or Magnet Room electronics (such as the Scan Room Interface (SRI) and Patient Blower), a LOTO-authorized GE Field Engineer (FE) must perform the steps in this Lock Out / Tag Out (LOTO) procedure. Completing all steps in this procedure ensures a safe environment when working on these parts.
Note: Observe the following:
  • There are two types of PDUs/PGR Cabinets. The LOTO steps are the same, but the physical components are slightly different.
  • This procedure does not cover the Gradient Filter. For LOTO requirements of the Gradient Filter, refer to LOTO for the PGR PDU/Gradient Subsystem.
Affected by LOTO
Name of equipmentNumber of locksTitles of employees authorized to perform LOTOTitles of affected employeesHow to notify
Examples of RF Subsystem components

  • RF Amplifier located in Power, Gradient, RF (PGR) cabinet

  • Optional Multi-Nuclear Spectroscopy (MNS) Amplifier

Examples of Pen Cabinet Electronics

  • Scan Room Power Supply (SRPS)

  • Patient Handling Power Supply (PHPS)

  • Driver Module

Examples of Magnet Room Electronics

  • Patient Blower

  • RF Hub

  • RF Hub Blower

1 per GE Field Engineer (FE)GE Field EngineersHospital PersonnelVerbal, Posted signs

Note: The following table describes the type, location, and magnitude of energy to be LOTO’d.
Energy sourceYesNoLocation of energyMagnitude/type of energy
ElectricalxPower, Gradient, RF Cabinet (PGR) PDU (power distribution unit) Circuit Breaker Panel208 VAC
Pneumaticx
Hydraulicx
Gas/Water/Steamx
Chemicalx
Mechanical Motionx
Gravityx
Springsx
Thermalx
Stored EnergyxTime discharge of internal capacitors170 VDC
Air Under Pressurex
Oil Under Pressurex
Water Under PressurexHeat Exchanger Cabinet (HEC) PGR Pump Circuit Breaker (PPMPCB) and RF amp quick disconnect5.0 Bar (80 psi)
Gas Under Pressurex
Steamx
Otherx

Procedure

  1. Notify affected personnel working in the area that LOTO is being performed.
  2. Make sure the host computer is shut down.
  3. Turn the circuit breaker at the bottom of the RF amplifier to the OFF position.
    Figure 1. MR750w RF amplifier circuit breaker
  4. At the front panel of the PDU, switch the PDM-RF (or RF+MNS) circuit breaker to the OFF (down) position.
    Figure 2. Old style RF amp circuit breaker
    Figure 3. New style RF amp circuit breaker
  5. At the front panel of the PDU covering the circuit breakers, apply a personal LOTO device for each FE working on the equipment.
  6. Make sure the power is OFF. Look at the RF Amplifier LEDs to see that all LEDs are dark to visually confirm that the power is OFF. The following illustration shows an typical RF Amplifier with the LEDs still lit.
    Figure 4. LED example

    You can verify that all energy has been dissipated by measuring 0 VAC at the terminal block, as described below.

    Note: It may take several minutes for lights to completely turn off.

    If the LEDs are on, confirm the PDM-RF (or RF+MNS) circuit breaker is in the OFF position.

  7. Measure voltage across the terminal block where the RF Amp receives power.
    1. Put a test lead at the ground terminal.
    2. Test for voltage across all the other connected terminals (L1, L2, L3).
    3. Confirm 0 volts before proceeding.
      Figure 5. Terminal block (MR750w)