Appendix - Fault Isolation

Green On

Green On

Red Off Green Off

Green On

Red On Green Off

Green Off

Red On Green Off

Green Off

Red Off

DC output power good.

AC input power good.

AC input power good.

DC output power fault.

Unit faulty and needs service.

Power is off.

A.2.2 Disk Shelf LEDs

A.2.2.1 Disk Power Supply LEDs

A.2.2.3 SE/LVD Terminator Module

This unit is located above the three fan modules on the right of each of the two disk shelves (rear). Since the terminator should always be in SE mode:

The green LED over "SE" on the right should be on

The green LED over "LVD" (Low Voltage Differential) should not be on.

A.2.2.4 SES Unit Module

This unit is located above the three fan modules at the top middle of each of the two disk shelves. There is a LED above the word "Temp", this LED is not used and should not be on. Next to "Temp" there is a "Mute" knob, this also is not used and shouldn't be touched.

A.2.2.5 SE-SE I/O Repeater Module

This unit should be located above the three fan modules at the top left of each of the two disk shelves (rear). There are no LEDs to be concerned with in the SE-SE I/O Repeater Module.

A.2.2.6 Fan Units (3)

Three fan units are located on the bottom part of each of the disk shelves (rear).

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Lucent Technologies PA-8500 manual Disk Shelf LEDs