ADTRAN 25 manual Maintenance

MAINTENANCE

Each power supply has one green LED on its front that can be seen through the fan assembly. The LED is visible through the ventilation slots on the front cover, but the cover must be removed for diagnostic and service purposes. This LED is always lighted when the system is receiving 5.1 volts power. The LED is dark when there is a failure in the +5 volt power supply or power connections, or when there is a short on the backplane.

If the green LED on the power supply is dark, first make sure that the cabinet is receiving ac power. Be sure that the fans are running, that the connection to building ac power has been made correctly, and that the power rocker switch is in the ON (1) position. See DANGER below. Then check the internal power connections (see Figure 4-8).

Danger: The power cord must be unplugged before the rear

cover is removed. Simply setting the power switch to

OFF is not sufficient.

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