panel. For racks with redundant power supplies, turning both power supplies on ensures the rack remains energized if one power supply fails.

Fuse

The fuse protects the power supply card from an over current condition. The fuse for the AC power supply is a 250VAC 3A fuse. The DC power supply uses a 250VAC 5A fuse.

LEDs

Two LEDs on the power supply card indicate the power supply status. These LEDs are not normally visible because they are blocked by the control panel and power supply circuitry. Their primary purpose is for troubleshooting if the rack has power problems. An Amber LED lights when the power supply has power available but the power supply switch is off, (e.g. the master switch is on and external power is connected). A green LED next to the amber LED lights when the power supply is on.

Rear Panel

The rear panel has all the connections for hooking up phone lines and computers to the U-336R/RE modem cards as shown below:

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Image 17
ZyXEL Communications RS-1612 manual Rear Panel, Fuse, LEDs