Navien NCB-24LSWE, Service Manual

Page: 125 / 144

NCB Service Manual 123 Version 1.0
6.2 Components Replacement
Instructions
6.2.1 PCB
1. Turn off the gas supply to the unit.
2. Disconnect the unit from the power supply.
3. Turn off the water supply to the unit.
4. Remove the 2 screws from bottom PCB bracket and
upper PCB bracket.
Figure 1
5. Disconnect all wiring connectors from the PCB
Figure 2
6. Remove the old PCB and replace it with the new part.
7. Reattach all wiring connectors to the PCB.
8. Set the proper DIP S/W settings on the PCB (refer to
page 20).
9. Reinstall the PCB and Front Panel using the 2 screws
previously removed.
10. Turn on the water and gas supplies, then reconnect
the power supply to the unit.
NOTE
All wiring harness connections to the
PCB should match in colour and pin
types. Do not use excessive force
when removing the connectors as
this may cause damage to the PCB.
6.2.2 Fuse
1. Turn off the gas supply to the unit.
2. Disconnect the unit from the power supply.
3. Locate the fuse housing shown in the figure below.
Open the housing to expose the fuse.
Figure 3
4. Replace the old fuse with the new part.
5. Ensure that the new fuse is of an equivalent rating
and that it is properly fixed inside the housing.
6. Close the fuse housing.
7. Turn on water supply, power supply, and gas supply
to the unit.
6.2.3 Fan Motor (Combustion Air)
1. Turn off the gas supply to the unit.
2. Disconnect the unit from the power supply.
3. Turn off the water supply to the unit.
4. Remove the mounting screw from the fan assembly
as shown in Figure 4 below.
5. Remove the fan assembly bracket with the attached
intake port.