If this LED does not go on, or if it goes off while system power is still applied, there could be a problem with either the source power itself or the DC output voltages being delivered to the backplane (+5 VDC and –48 VDC). There could also just be a problem with the MBus controller inside the power supply.
The AC INPUT OK LED (AC-input power supply) or the INPUT OK LED (DC-input power supply) stays on when all of the following conditions are satisfied:
—The power supplies are on and receiving normal source power.
The source power specifications for the AC-input power supply are 180 VAC to 264 VDC, 50 to 60 Hz, single phase.
The source power specifications for the DC-input power supply are –40.5 VDC to –70 VDC.
—The power supplies are providing the nominal +5.2 VDC and –48 VDC operating voltages to the backplane.
If the AC or DC source power or the DC operating voltages being supplied to the backplane fall outside the allowable tolerances, the OUTPUT FAIL LED on the power supply goes on, because a problem with either of the DC operating voltages being supplied to the backplane prevents the system from starting up or continuing normal operations.
For example, if a problem occurs with the –48 VDC line that supplies power to the router’s internal components (see Figure 1-23), the system fails during the boot sequence.
Depending on when the OUTPUT FAIL LED goes on, proceed as follows:
—If the AC INPUT OK LED (AC-input power supply) or the INPUT OK LED (DC- input power supply) stays off when system power is applied, there is a problem with either the AC or the DC source power or the connection to the power supply. In this case proceed to the section entitled “Troubleshooting the Power Subsystem.”
—If the AC INPUT OK LED (AC-input power supply) or the INPUT OK LED (DC- input power supply) goes on temporarily and then goes off within 30 seconds, the system is probably shutting itself down because it detected an out-of-tolerance power or temperature condition within a power supply. In this case proceed to the section entitled “Troubleshooting the Power Subsystem.”
