Hardware Maintenance Procedures
The procedure for replacing a model B
WARNING! A replacement DC power supply should never be placed in an 
contains an AC power supply, and 
If these instructions are not heeded, there is a risk of electrical shock, danger to personal health, and serious damage to the equipment.
WARNING! It is highly recommended that you use the included grounding strap when handling this or any other component.
1.Determine which power supply is defective by examining the power supplies themselves. An extinguished “PWR OK” LED or an illuminated “FAULT” LED indicates the failed supply. On an
WARNING! Failure to perform Step 2 can result in serious injury to the user or damage to the equipment.
2.Turn OFF the power switch on the front of the defective power supply. Wait at least one (1) second after turning off the power before moving on to the next step.
3.Disconnect the AC line from the front of the defective power supply.
4.Unscrew the two captive fasteners (one on the upper, left corner of the faceplate and one on the lower, right corner of the faceplate, see Figure 3.3) using a straight blade screwdriver.
