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NK-3G144 User Guide (v04) Maintenance • 55
Maintenance
This chapter covers the maintenance of NK-3G144. Refer to this chapter to replace a power supply unit, replace a
matrix or control card, and to replace and clean the fan filters.
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Any maintenance performed inside the chassis should be restricted to service personnel only.
Replacing a PSU in the NK-3G144
To replace a PSU in the NK-3G144
1. Unscrew the screw on the front door of the NK-3G144 (see Figure 7.1 ).
Figure 7.1 NK-3G144 — Location of Front Door Screw
2. Open the front door.
3. Switch off the PSU using the switch on the front of the PSU.
4. Unscrew the two captive screws in the PSU from the frame.
5. Gently but firmly pull the PSU PCB out of the hole where it connects with the motherboard at the back of the
frame.
6. Install the replacement PSU (see “ Installing a PSU into the NK-3G144 ” on page 24).
7. Close the front door.
8. Insert and tighten the front door screw to secure the front door of the NK-3G144 shut.
Caution
— When the frame is energized, Hazardous Energy Levels are present on the chassis
midplane where I/O card resettable fuses make contact with the 15V DC supply bus. Hazardous Energy
Sources can cause fire or serious burns under short circuit conditions. Access to the inside chassis
areas should be restricted to service personnel only, by use of the chassis door screw provided. The
screw should be engaged to limit access to the inside chassis without a tool.
Servicing within the chassis while energized should be limited to module card or supply installation, or
defect replacement. Installation of the cards should be carried at the front of the enclosure and care
should be taken to avoid any card or user contact with the resettable fuses on the chassis’s midplane.
All other service or repair should be carried out off-line with the chassis in a de-energized state.
ESD Susceptibility
— Anti-static precautions must be taken when fitting or removing a PSU.