AT&T MERLIN LEGEND Installation & Maintenance Manual page 117

Installation
CAUTION:
To prevent damage from electrostatic discharge (ESD),
avoid touching leads, connectors, pins, and other
components when handling the circuit board. Use a
properly grounded wrist strap.
Modify Processor Module for Key-Only Operation
The system can be configured to operate in Key, Hybrid/PBX, or
Behind Switch mode. The mode of operation is chosen and
registered with the FCC before the system is installed. The
processor module is configured for the multifunction (MF) option
when shipped.
The MF option allows the system to operate in any of the three
modes (Hybrid/PBX, Key, and Behind Switch), according to how
the software is administered. The Key function (KF) option
restricts system operation to Key-only mode. Software
programming of PBX features and pooled trunks is not possible
in this mode.
Follow these steps to modify the processor module for Key
operation (see Figure 18):
1. Remove the processor module from its package. Do not open
the module case.
CAUTION:
Do not touch the HDR3 header. If the HDR3 header is
disturbed, the system default memory can be lost.
2. Locate the header marked HDR4 on the module's circuit
board.
3. Locate the shunt attached to one of the pins of the HDR4
header.
4. Remove the shunt from the single header pin; then reinsert it
so that it covers both pins on the header.
The Control Unit 3-9