Specifications

Section M
Controller (A31)
M.1 Introduction
This section describes the Controller board. Topics include Func-
tion, Location, Block Diagram Description, Detailed Circuit
Description, Troubleshooting, and Removal/Replacement.
NOTE: Parts List for this board is on Section VII.
M.2 Function
The purpose of the Controller is to provide Local/Remote Step-
Start Sequence control of the Low/Med/High power levels,
monitor transmitter operation and protectively respond to exter-
nal or internal fault conditions, and provide metering functions
in addition to status indicators.
M.3 Location
The Controller board is located on the back of the center control
compartment front door (SEE VIEW 13).
M.4 Block Diagram Description
The Controller uses PAL integrated circuits (Programmable Ar-
ray Logic). These PALs are grouped to perform various func-
tions. PALs are devices that can be programmed to implement
complex logic functions with up to twenty-two inputs and ten
outputs. The 22V10 PAL used in the transmitter uses AND/OR
logic array structure, which directly implements sum-of-prod-
ucts equations. The equations are programmed into the device
through electrically-erasablefloating-gate cells in the AND logic
array. The fixed OR logic array offers a varied number of product
terms per output and can be programmed as registered activehigh
or active low.
Refer to Figure M-1 Controller Power Control Block Diagram
for the following discussion.
M.4.1
Power Level Selection and Power Lower/Raise
Control - OPR and LR PALs
These PALs work together to generatethe Turn On Request when
a power level is selected, control the Lower/Raise function, and
produce the VSWR Test signal when required.
The OFF, LOW, MED, HIGH, LOWER, and RAISE control
inputs from the External Interface board are processed by the
OPR (Operator) PAL and the LR (Lower/Raise) PAL.
These same inputs from the Switch board on the front panel are
applied to Transistor Inverters and connected to the OPR and LR
PALs.
If there are no present faults, the ENTOR (Enable Turn On
Request) from the FLT1 PAL will allow the LR PAL to generate
a TOR (Turn-On Request) when a power level is selected. This
TORissenttothePWRandPTIMPALs.
Both PALs provide outputs to the Switch board, External Inter-
face, and to the Analog Input board for status and control func-
tions. Transistor Inverters provide the proper voltage levels for
operation.
During powerlevelselection, power levelchange, or by a Manual
VSWR Test, the LR PAL generates the VSWR Test signal that is
used by the Output Monitor board. The Pass/Fail results of this
test are determined on the Output Monitor board.
After the transmitter is operational on the selected power level,
the Lower/Raise controls are activated and fine power level
changes can be made to the transmitter.
M.4.2
Step-Start Sequence Control - PWR and
PTIM PALs
These PALs work together to generate the Step-Start Sequence
outputs to the transmitter and the Enables used by the Fault
Handling PALs on the Controller.
When a Turn-On Request (TOR) is received by both the PWR
(Power) and PTIM (Power Timing) PALs, the PTIM PAL starts
the initial sequence by sending a Time pulse to the PWR PAL 1.5
seconds after the TOR is produced.
The PWR PAL sequentially controls the Step-Start function by
activating Relay Driver Transistors that control relays in the RF
Amp Power Supply and activating the TX ON Enable that is used
by several other boards in the transmitter.
When the relays close sequentially, the Low Voltage Supply
Sensing and Status signals tell the PWR PAL the transmitter has
responded properly and it is acceptable to go the next step.
The PWR PAL must receive Time signals from the PTIM PAL,
before executing each step.
The PWR PAL also generates the Enable 1, Enable 2, and Enable 3
signals that are used by the Fault Handing and Latch PALs.
An 8 kHz Clock is Divided down several times to provide six
different clock frequencies used by different PALs.
Refer to Figure M-2 Controller Fault Handling Block Diagram
for the following discussion.
M.4.3
Fault Types and Fault Input Latches
All fault inputs generated by the transmitter are applied to Fault
Input Latches and can be categorized by the type of Controller
response:
RF MUTE
This type fault will lower the power to zero by turning all Big
Step and Binary RF Amplifiers OFF, but it does not to turn the
transmitter OFF.
FOLDBACK FAULT
Foldback faults will reduce the power output in steps, the amount
of attenuation is determined by the type and length of the fault. If
888-2339-002 M-1
WARNING: Disconnect primary power prior to servicing.