Maintenance
7-18 AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
7.10 Replacing the Power Supply PCB and Monitoring PCBof the Fan Subassembly

Exchanging the Mother Board

1. Disconnectthe power cable of the fan subassembly from the supply.
2. Usea screwdriver to make a quarter turn counter-clockwise and open the two
quick-release locks on the front of the fan subassembly.
3. Removethe base of the fan subassembly (see Section 7.9).
Shown in the following figure is a front view of the fan subassembly.You can also
see the locations of the printed-circuit boards (PCBs).
Fan1 Fan2 Fan3
Power supply
PCB
Monitoring
PCB
Quick-release
lock Quick-release
lock Reset button
4. Pullthe faulty PCB forward and out of the fan subassembly.
5. Slidethe new PCB in until it engages.
6. Slidethe base in again and press it up.
7. Usea screwdriver to make a quarter turn clockwise and close the two
quick-release locks.
8. Connectthe power cable of the fan subassembly to the supply.
9. Usea pointed object to press the RESET button. The fans will start running.
!Caution
Electronic components can be damaged.
If you do not observe the ESD guidelines when handlingprinted-circuit boards with
electronic components, the components can be damaged by a static discharge.
Observe the ESD guidelines (see Appendix).