Installation Instructions

1X UBS Macro B T S FRU –48 V DC P ower Supply Module (PSM) Shelf
PSM shelf DC I/O interconnection
Each PSM slot in the –48 V DC PSM shelf has two contacts (– feed and + return) for 48 V DC
input and two contacts (+ feed and – return) for +27 V DC output.
The –48 V DC PSM shelf has DC I/O bus bars at the rear of the shelf . The 48 V DC input contacts
of the three PSM slots are parallel connected to the DC input bus bars. The +27 V DC output
contacts of the three PSM slots are parallel connected to DC input bus bars.
The DC input bus bars are interconnected to the –48 V DC input power connector on the rear of
the PSM shelf .
The DC output bus bars are interconnected to the +27 V DC output power cable on the rear
of the PSM shelf . This cable connects to the +27 V DC input power cable on the rear of the
UBS Macro PDU . The PDU distributes the +27V DC operating power to the UBS Macro frame
electronics.
PSM shelf alarm and control I/O interconnection
Each PSM slot has a bulkhead connector . The I/O signals of each of these slot connectors are
interconnected to the ALARM & CONTROL connector on the front of the –48 V DC PSM shelf .
Each –48 V DC PSM has a rear panel status/alarm drawer connector that mates with the
bulkhead connector in the PSM slot of the PSM shelf . The I/O signals of this connector are
interconnected to the ALARM & CONTROL connector on the front of the –48 V DC PSM shelf .
This connector is cabled to the S SI front panel PSM connector . This allows the PSM alarm &
status to be monitored by the S SI. It also allows the front panel LEDs and module enable to
be controlled by the S SI.
PSM alarm & status signal inputs are current share, temp alarm, converter fail, fan fail, high
temp, low bus voltage, input voltage loss, presence, and EID .
The current share signal goes directly from one PSM to the others via PSM shelf backplane
looping without going to the S SI. Based on PSM alarm & status, the S SI outputs signals to
control the state of the LEDs.
The PSM shelf ALARM & CONTROL cable also contains the PSM enable line which
must be grounded at the S SI in order for the PSM to operate.
System impact/considerations
P erforming this replacement procedure will cause BTS downtime and interrupt all
call processing.
68P09283A64 -3 10 -3
FOA SEP 2007