Dell PowerVault 720N Installation And Troubleshooting Manual page 56

3-4 Dell PowerVault 720N, 740N, and 760N Installation and Troubleshooting Guide
Table 3-2 describes the power supply LED codes on the back panel.
DC Green
AC Yellow
On — DC power is good.
Off — DC output power is not good.
If the DC green LED is off, contact a service
technician to replace the power supply.
If one power supply fails, the message, Power
supply degraded . . . appears on the
LCD. A similar message appears on the system
console telling you which power supply failed.
The message, Power good, also appears on
the LCD and console, indicating that the second
power supply is maintaining the filer.
On—AC signal is good.
Off—AC signal is not good.
If the AC LED is off but the power LED on the
front panel is on, the second power supply takes
over and maintains the filer. In either case:
Ensure that the power supply is fully
installed and locked into place.
Ensure that the power switch is in the On
position.
Check the power source.
If the preceding actions do not correct the
problem, contact Dell technical support for
help.