888-2406-002 4-7
WARNING: Disconnect primary power prior to servicing.
Overall System Theory
4.3.3.1 Main/Alternate Exciter Switching
Exciter selection is done via relay K1 and the EXCITER SELECT control signal
from the Life Support Board. The EXCITER SELECT signal is normally low which
places K1 in the position shown on the schematic, sending the Exciter 1 RF output
to the IPA input relay K2. If EXCITER SELECT goes high, K1 will be energized
and switches to the Exciter 2 RF output. This switching will take place
automatically if an exciter fault is detected by the Master Controller board. Exciter
switching can also be done manually using the Diagnostics display. Press [HOME,
STATUS D,C] (this code is explained in Section III, Operation). This should bring
up the screen in Figure 4-2. Pressing the D function key will now toggle K1,
switching from exciter 1 to exciter 2 or vise versa.
NOTE:
For easy navigation through the Diagnostic menus, refer to “Using the Diag-
nostic Display” in Section III, Operation and to the“Diagnostics Display
Menu Tree”, in the schematic package, which gives a complete overview of
the Diagnostics menu structure.
4.3.3.2 Main/Alternate IPA Switching
Selection of IPA_1 or IPA_2 (both input and output) is done via relays K2, K3 and
the IPA DRIVER SELECT control signal from the Life Support Board.
K2 switches the input RF drive from the exciter to IPA_1 or IPA_2 while K3 selects
the active IPA RF output. The control signal, IPA DRIVER SELECT, is normally
low which places K2 and K3 in the IPA_1 position as shown on the schematic. If
IPA DRIVER SELECT goes high, K2 and K3 will be energized and switch to the
IPA_2 position. If the Master Controller detects a loss of RF output from the active
IPA it will automatically switch to the second IPA. IPA switching can also be done
manually using the Diagnostics display. Press [HOME, STATUS D,B] This should
bring up the screen in Figure 4-3. Pressing the D function key will now toggle K2
and K3, switching from IPA_1 to IPA_2 or vise versa.
Figure 4-3 IPA Status and Manual Switch Screen
[HOME, STATUS D,B]
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