Discovery MR750 3.0T System Service Methods
5690009-2EN Revision 4
Object ID: 00000018WIA30DF4450GYZ
Topic ID: id_2022137 Version: 1.12
Date: Oct 11, 2021 6:20:13 PM

Replacing the 48V power supply

Prerequisites


Personnel requirements
Required persons	Preliminary requirements	Procedure	Finalization
1	5 minutes	60 minutes	25 minutes


Tools and test equipment
Item	Quantity	Part number	Manufacturer
Nonmagnetic Titanium Service Tool Kit, Large Set	1 of either tool kit	5112581	-
Nonmagnetic Titanium Service Tool Kit, Small Set	1 of either tool kit	5113258	-


Consumables
Item	Quantity	Part number	Manufacturer
GE Equipment Maintenance Sticker	1	5661793	-


Replacement parts
Item	Quantity	Part number	Manufacturer
Delta 48V 2500W Power Supply	2, if replacing Condor power supplies	5745311	Delta
Delta 48V 2500W Power Supply	1, if replacing a faulty Delta power supply	5745311	Delta
Delta 48V Power Supply Kit for the Gradient Subsystem (XGD) Power Distribution Unit (PDU)	1	5140621-10	Delta
Delta 48V Power Supply Bracket for the Gradient Subsystem (XGD) Power Distribution Unit (PDU), Blind-Mate	1	5343114-10	Delta

About this task

Due to frequent repairs on the 48V PDU power supplies in the XGD and XGD2 PDUs, the Condor power supply (5140621-4) is being replaced with the Delta power supply (5745311). When either of the current Condor PS1 or PS2 power supplies fail, both Condor power supplies need to be replaced with two Delta power supplies and a new Delta compatible bracket.

Note: The Delta power supply bracket has been redesigned to allow "blind mating" for more efficient future repairs. The blind mate bracket (5343114-10) will be phased into new production and service inventory once the existing supply of Delta power supply brackets (5140621-10) decreases.

Procedure

Use one of the following methods to identify the type of power supply currently installed in the PDU:
- Find the manufacturer (Condor or Delta) on the GE Equipment Maintenance Sticker (5661793), which is located on the front of the PDU.
- Look through the PDU vent holes with a flashlight. A Delta power supply has an EnergE label.
  Figure 1. PDU vent holes (left) and power supply EnergE label (right)
Result
If the faulty power supply is a Condor, follow the steps in this procedure to replace both Condor power supplies with Delta power supplies and a new Delta compatible bracket. If the faulty power supply is a Delta, follow all applicable steps to replace the faulty power supply.
Perform LOTO on the PDU. See the MR Service Safety Manual (5452735).
Remove the four 6-32 x 3/8 screws on the circuit breaker guard using a Phillips screwdriver.

Note: Do not recycle the screws, as you will use them to reattach the guard.

Figure 2. PDU circuit breaker guard screws
Remove the 10-32 x 1/2 screws on the front panel using a Phillips screwdriver.

Note: Do not recycle the screws, as you will use them to reattach the front panel.

Figure 3. PDU front panel screws - XGD (left) and XGD2 (right)
Carefully pull on the front panel, and angle it down and away from the unit.

Note: Be careful not to damage the leak sensor strip.

Figure 4. Removing the front panel
Disconnect SW1 and SW2 from the back of the front panel. Turn the tabs counterclockwise and carefully pull them away from the panel.

Figure 5. SW1 and SW2 tabs
Disconnect the P8 and J8 15-pin housing connectors. Press down on the locking tabs and pull the connectors apart.

Figure 6. P8 and J8 housing connectors
For both XGD and XGD2, remove the three 10-32 x 1/2 screws from the PDU receptacle assembly, which is on the bottom of the unit.

Note: If you are replacing a faulty Delta power supply in an existing blind-mate bracket assembly, you do not need to remove these screws; in a subsequent step you will unlock the mounting pins to remove the power supply.

Note: Do not recycle the screws, as you will use them to reattach the assembly.

Figure 7. PDU receptacle assembly screws
Lift the assembly away from the unit.
If any wires attached to the circuit breaker(s) will prevent you from having enough space to remove the power supplies, do one of the following:
- Use masking tape and a marker to label these wires, and then disconnect them.
- Remove the mounting screws from the circuit breaker(s), and move the circuit breaker(s) to the side.
  Note: Do not recycle the screws, as you will use them to reattach the circuit breaker(s).
Figure 8. Impeding wires attached to circuit breakers - XGD (left) and XGD2 (right)
Remove the two Keps nuts and washers that secure the power supply assembly, and the two Keps nuts and washers that secure the ground wires.

Note: Do not recycle the nuts and washers, as you will use them to reassemble the power supply assembly and reattach the ground wires.

Figure 9. Keps nuts and washers

Note: If necessary, cut the tie that secures the power supply harness to increase slack.
Figure 10. Power supply harness tie
Carefully pull the power supply assembly out, lifting it over the studs and moving it forward out of the PDU.

Figure 11. Removing the power supply assembly^*
^*The power supply assembly in this image is a Condor, but the process of removing a Delta power supply assembly is the same.

Note: Make sure to move the RF cable out of the way so the power supply housing does not damage the cable's outer jacket.
Figure 12. RF cable

If this is the first time that Delta power supplies are being installed, do the following:

Use masking tape and a marker to label the run number and description on each wire connected to the Condor terminal block, located at the rear of the power supply.

Figure 13. Terminal block on the Condor power supply assembly

Table 1. Terminal block wires
From Condor terminal block slot	Run number	Description	To Delta terminal block slot
PS1 J1 #1	89	L AC Input Line	1
PS1 J1 #2	90	N AC Input Neutral	2
PS1 J1 #3	91, 99	G AC Input Ground	3
No connection	No connection	No connection	4
PS1 J7 #1	93	PS1- Return	5
PS1 J7 #2	107	PS1- Return	6
PS1 J7 #3	108	PS1+ 48V	7
PS1 J7 #4	94	PS1+ 48V	8
PS2 J7 #1	95	PS2- Return	9
PS2 J7 #3	96	PS2+ 48V	10
PS2 J6 #3	98	B1 Common	11
PS2 J6 #4	97	C1 Inhibit	12

Disconnect the wires from the faulty power supply assembly.
Attach the marked wires to the terminal block on the Delta power supply bracket, matching the wire labels to the labels on the bracket.

Note: The Delta labeling shows the run number and the terminal block number with description (pin 1 is on the left).

Figure 14. Pin 1 on the Delta power supply brackets - existing (left) and blind-mate (right)

If you are replacing a faulty Delta power supply, complete the following substeps to remove the power supply from the power supply bracket.

Delta bracket type

Substeps

Existing (5140621-10)

Loosen the bottom three screws on one side of the power supply bracket.
Note: Do not remove the screws from the bracket.
Figure 15. Power supply bracket screws
Disconnect the power supply connector from the rear of the power supply (PS1 if you are replacing the top power supply; PS2 if you are replacing the bottom power supply).
Figure 16. Power supply connectors
1 PS1 connector
2 PS2 connector
Push the slide buttons on the left and right sides of the front of the power supply to release the mounting pins from the holes on each side of the bracket.
Figure 17. Power supply slide buttons and mounting pins
1 Slide buttons
2 Mounting pins
Carefully pull the power supply from the bracket.

Blind-mate (5343114-10)

Push the slide buttons on the left and right sides of the front of the power supply to release the mounting pins from the holes on each side of the bracket.
Figure 18. Power supply slide buttons and mounting pins
1 Slide buttons
2 Mounting pins
Carefully pull the power supply from the bracket.
Figure 19. Removing the power supply from the bracket - top supply (left) and bottom supply (right)

Complete the following substeps to install a new Delta power supply.

Note: If this is the first time that Delta power supplies are being installed, you must perform this step twice to install both power supplies.