Remove Power and Access the Primary CPU Bay
If you have not already removed all system power and accessed the appropriate bay for replacing the class B motherboard, follow the instructions
below. Otherwise, move on to the next subsection, titled “Remove the Existing Class B Motherboard.”
1. Remove any connection to standby batteries at the PDM and then remove system power at the breaker.
2. Lower the front door to the Secondary CPU bay. Refer to Figure 4 for the location of the class B motherboard within the bay.
Figure 4: Secondary CPU Bay Layout (4100U depicted)
Remove the Existing Class B Motherboard
1. Label and detach the service port and front display ribbon cables from the CPU daughter card mounted to the class B motherboard. The
service port cable is the thinner of the two cables.
2. Remove the CPU daughter card installed in the expansion card slot of the class B motherboard.
3. Label and remove the harnesses attached to connector locations P2 and P3 on the class B motherboard (see Figure 4 for locations).
4. Label and remove any wires connected to the terminal blocks on the class B motherboard. Include as part of the label the name of the
terminal block and the specific terminal the wire connects to. You will reconnect these wires to the new class B motherboard.
5. Remove the four #6, 5/16” Torx screws from each corner of the motherboard. These screws are fastened to metal standoffs connected to the
rear of the bay. Leave the standoffs fastened to the back of the bay. You will mount the new class B motherboard to them.
Install the New Class B Motherboard
1. Position the new motherboard in the same location where you removed the old one.
2. Fasten the new class B motherboard to the four standoffs extending from the rear of the CPU bay using the four #6 5/16 inch Torx screws
provided with the service kit.
3. Reconnect the labeled cables and wires to the appropriate locations on the new class B motherboard.
4. Reinsert the CPU daughter in the expansion card slot on the newly installed class B motherboard.
5. Reconnect the service port and front display ribbon cables to the appropriate locations on the CPU daughter card. The service port cable is
the thinner of the two cables.
Prepare System for Operation
Once all the wires have been reattached and the board has been successfully replaced. Complete the replacement procedure by following the
instructions below.
1. Close the door to the expansion bay containing the replaced motherboard.
2. Reapply system power at the breaker.
3. Restore battery power to the cabinet by reconnecting the battery cable at the PDM.
4. Redress and close the main cabinet door.
The system is now ready for normal operation.
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579-272 Rev. C
CPU Switcher Card and Class B Motherboard Replacement Instructions
