5190/5194 Modular Tape Subsystem Manual

Adding, Removing, and Replacing CRUs
5190/5194 Modular Tape Subsystem Manual—426878-002
6-2
Replacing a BEB
Replacing a BEB
The back-end board (BEB) translates fiber-optic signals from a 3216 controller or a
6761 fiber-optic plug-in card (F-PIC) on a 6760 adapter into SCSI commands and
information for the 5190 and 5194 tape drives.
The BEB contains four light-emitting diodes (LEDs) with the following functions:
You can see the internal LEDs by looking through the slots in the BEB enclosure.
They are next to each other, near the bottom edge of the BEB circuit board. The
internal LEDs are considerably smaller than the external LEDs and difficult to see
when not lit. The internal LEDs are used by trained service providers. Customers do
not need to use these LEDs to troubleshoot the BEB.
Troubleshooting a BEB
If either external BEB LED is not lit when power is applied to the drive CRU, there is a
problem. Table 6-1 lists possible causes listed in order of likelihood, where 1 is the
most likely cause.
BEB LED Function
Green external LED Indicates that the BEB has power.
Yellow external LED Indicates that the optical carrier signal is present.
Amber-orange internal
LED
Indicates an error condition.
Yellow internal LED
(locator LED)
(NonStop Himalaya K-series servers only) Is used as an aid in
identifying or locating the failing BEB (the tape drive CRU must
be attached to a 3216 controller). This LED can be flashed on
and off by the TMDS FLASH command.
Table 6-1. Troubleshooting a BEB
External LED Is Not Lit Possible Causes
Green (Power) 1. Drive CRU is powered off.
2. Drive CRU is powered on, but BEB power cabling needs
repair.
3. BEB has power, but the voltage is low.
4. LED circuitry is faulty.
Yellow (Carrier Signal) 1. Cable is connected improperly or disconnected.
2. 3216 logic board or 6760 adapter is not powered on.
3. Cable is broken or damaged.
4. LED circuitry is broken.