AT&T MERLIN LEGEND Release 3.1 Installation Manual page 53

Installing the Power Supply
Installing the power supply can involve as many as four procedures,
depending on the system configuration. The procedures are:
Turning off all power to the control unit
Installing a copper shield [for older power supply modules (391A1,
391A2, 391B1) only]
Installing the ferrite cores
NOTE:
It is not necessary to install ring generators in a new system with new 012
(apparatus code 517G13 or later) modules or new 008 (apparatus code
517D28 or later letter). If you are upgrading or using older modules, see
Maintenance and Troubleshooting .
Turning Off the Power
1 Turn off each power supply.
2 Disconnect all power cords and auxiliary units.
Installing a Copper Shield
The added power supply in each expansion carrier can cause excessive
noise in the module occupying the next slot. To eliminate this noise, a copper
foil shield is installed over the power supply. These shields and their labels
are packaged in the power unit shielding kit included with the expansion
carrier.
NOTE:
The 391A3 and 391B2 power supply modules do not require copper
shielding. Perform this procedure for older power supply modules (391A1,
391A2, and 391B1) only.
2–20
Installing the Control Unit