Switch Hardware
If a model B power supply goes into shutdown, it remains turned off until the fault condition is rectified. At that point, the power supply restarts itself, except in the case of an overvoltage condition.
To recover from a shutdown caused by an overvoltage state, the AC line input must be turned off for at least one second.
WARNING! A replacement AC power supply should never be placed in an 
contains a DC power supply, and 
these instructions are not heeded, there is a risk of electrical shock, danger to personal health, and serious damage to the equipment.
If the power supply needs to be replaced, please refer to Chapter 3, Hardware Maintenance Procedures, for
