SIGNA MR355 / SIGNA MR360
Service Manual
5856356-3EN Revision 5.0
Basic Service Documentation. Copyright General Electric Company.
Object ID: 00000018WIA30A80030GYZ
Topic ID: id_13105807 Version: 1.3
Date: Jul 5, 2019 11:49:11 PM

Gradient Filter

Prerequisites

Table 1. Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	Not Applicable	30 minutes	15 minutes

Table 2. Tools and test equipment
Item	Quantity	Effectivity	Part number	Manufacturer
Non Magnetic Tool Set	1	-	-	-
Digital volt meter (DVM) with alligator clip leads	1	-	-	-

Table 3. Replacement parts
Item	Quantity	Effectivity	Part number	Manufacturer
Gradient Filter (Refer to Illustrated Parts)	1	-	-	-

Table 4. Safety

DANGER

STRONG MAGNETIC FIELD!

FERROUS MATERIALS CAN BECOME DANGEROUS PROJECTILES IN THE PRESENCE OF THE MAGNETIC FIELD PRODUCED BY THE SIGNA MAGNET.

Do not Bring any ferromagnetic tools or equipment into the magnet room.

DANGER

FATAL ELECTRIC SHOCK HAZARD!!

THE GRADIENT Amplifiers ACT AS CONSTANT LOAD SOURCES, AND WILL SEND maximum CURRENT TO ANY LOAD including any human who get across the outputs.

TO PREVENT FATAL ELECTRIC SHOCK, Follow loto steps as given in first section of this document to disable and verify safe voltage levels.

Table 5. Required conditions
Condition	Reference	Effectivity
PDU must be turned OFF. Refer to Lockout / Tagout for PDU in System Cabinet.	-	-

Procedure

Remove SC Rear cover of magnet room side. Refer to SC Cover Removal
Remove the terminal Cover for defective Gradient Filter by removing 2 screws from gradient filter.
Check the voltage between Ground Stud and each terminal (+ or -). Verify that there is no voltage.

Notice

To prevent X-axis polarity swap, mechanical spacers are newly added to X-axis and new part number is assigned for G-Filter from 3Q, 2011. Keep the spacer on the cable end intact and maintain in the original location on cable when replacing G filter. Ensure the newly replaced gradient filter has the spacer pre-installed.

Remove the cable from defective gradient filter while keeping the spacer on cable intact.

Note:

Use two wrenches as illustration to tighten the nut. Need to tighten with enough torque to avoid spike noise. But, do not over tighten not to break stud.

Cut tie-wraps at defective Gradient Filter.

Figure 1. Remove the all cables
Remove the 24 screws from frame of gradient filter.
Remove gradient filter from Penetration Panel.

Figure 2. Remove Gradient Filter
Restore the Gradient Filter by tightening 24 screws.

Note:
Make sure to tighten each screw.
Connect Gradient Cables. Make sure screw is fixed, nut is tight, and cable is not detached from terminal.

Note:
Use two wrenches to tighten the nut.
Restore terminal Cover and restore Cabinet cover.

Finalization

Procedure

Restore the Power. Refer to Lockout / Tagout for PDU in System Cabinet.
Perform Geometry Verification.
Perform Signal to Noise - Head Scan.