AT&T MERLIN LEGEND Installation & Maintenance Manual page 114

Installation
Note: Each carrier that has 012 basic telephone or 008 OPT
modules must have a ring generator installed in the carrier's
power supply module before the power supply module is
installed in the carrier. Place all 012 and 008 OPT modules in
one carrier whenever possible.
WARNING:
Hazardous electrical voltages may be present if the
following steps are not performed correctly.
Follow these steps to install a ring generator:
1. Turn off the power switch at the power supply module.
2. If there is an auxiliary power unit, unplug it from the AC outlet
and then unplug it from the front of the power supply module.
3. Unplug the power supply module's power cord first from the
AC outlet (or from the auxiliary power unit) and then from the
front of the power supply module itself.
4. Remove the power supply module from the carrier.
Note: At this point there should be no cords connected to the
front of the power supply module.
Place the power supply module on its left side and remove
5.
the five screws.
6. Carefully turn the module over on its right side and remove
the left half of the power supply module.
Position a 129B Frequency Generator (ring generator) so that
7.
its screw holes are aligned with the screw posts on the power
supply module and the transformer is next to the main board.
8. Attach the ring generator to the power supply module with
four screws.
3-6 The Control Unit