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HARRIS
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WARNING: Disconnect and lockout AC primary power prior to servicing
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Status Indicators
The CPLD will give the following status indicators. A red LED will indicate a Board
Reset. A red LED will indicate if the CPLD is not programmed. Two red LEDs will
indicate a Faulted Off condition and a RF Mute condition.
5.5.1.7 Cabinet Bus Controller (Sheet 7)
Refer to sheet seven. This sheet contains the circuits that communicate with the slave
controller over the twisted pair ribbon cable cabinet bus. U84 is the chip that issues the
control commands to the slave controller cards. The U95, U96, U98 and U99 are the
transceiver chips that perform the two way communication of commands and status.
The U78 and U66 perform a conversion of the balanced analog signal to the unbalanced
input to U65. The TLV2548 is a serial analog to digital converter. Under the control of
the micro it will convert the analog voltage to serial digital data that the micro will
process for monitoring and display.
5.5.1.8 Transmitter ON/OFF Control (Sheet 8)
Each of the four chips on sheet 8 will switch the cabinet ON and OFF lines high and
low. An additional input is used to pulse the plus 12 volt lines for resetting modules or
power supplies that are reporting a fault to the slave controller. Part of U97 is used to
control the relay K2. K2 can be used to control exhaust fans or other parts of a
transmitter cooling system.
5.5.1.9 Foldback Voltage D / A and Can Bus Interface (Sheet 9)
The foldback digital to analog converter changes the digital foldback control value to an
analog voltage. The analog voltage is an input to the exciter I/O to control the foldback
circuitry of the exciter. Provisions include two outputs for analog transmitters. The
foldback is again buffered by the U4 on sheet 10. Test points are available to monitor
these DC control voltages. The bottom part of the sheet shows the CAN interface that
communicates with the GUI computer display unit.
5.5.1.10 Controller/Exciter Switcher Interface (Sheet 10)
J8 is the controller input / output that goes to the exciter I/O panel either directly or as
switched by the I/O control switching relays in the exciter switcher. The exciter sense
lines are used for exciter power metering. This allows the front panel and the GUI to
control the exciter switcher and the exciter power.
5.5.1.11 Line Voltage and AGC Monitoring (Sheet 11)
The opto-coupler supply AGC status to the multiplexer chip U48, the one output line
allows the microprocessor to poll the AGC to see if the status is ON or OFF. The AGC
control voltages are buffered and become input to multiplexer U57.
DC sample voltages from the AC line sample units are adjusted to a nominal DC
voltage of three volts or less at the test points. The actual calibration scaling is done by
the microprocessor. There are two AC line sample sections for those systems that dual
AC power feeds to the control cabinet.
