Specifications

way of being sure that the detector circuit will return a
fault to the front panel, if one does occur.
6.4.11
Output Monitor Supply Fault
If the transmitter has shut itself off or is operating with an RF
Mute indicator lit, and the OUTPUT MONITOR SUPPLY
FAULTLED on the Control front panel is illuminated RED, then
one or more power supplies has failed on this board. With the
low voltage on, measure the following voltages on the Output
Monitor.
a. F1 should measure +22VDC, F2 should measure +8VDC,
and F3 should measure -22VDC. If any one of these
supplies is not present, troubleshootthe lowvoltagepower
supplies.
b. If all of these supplies are present, refer to the Trou-
bleshooting section of the Output Monitor board.
6.4.12
Analog Input Power Foldback
This LED is not a fault indicator, but rather an indication that
the transmitter is, or has been, in a self protection mode.
6.4.12.1 Reset the Fault
a. If the FAULT RESET pushbutton on the Control front
panel is pressed and the LED returns to GREEN, then the
fault that caused the foldback is no longer present and the
condition should be monitored.
b. If the LED remains RED after the FAULT RESET push-
button is pressed, then the fault that caused the foldback
is still present.
1. The transmitter will normally be in the foldback mode
due to Antenna/Network VSWR or ARC, RF
Amp/PowerSupply Temp, or Air Flow Reduced faults.
2. The transmitter can also be in this mode due to failures
of the sensing and control circuitry. Refer to the appro-
priate fault section or to the troubleshooting guide of
the Controller and/or Analog Input board as needed.
6.4.13
Analog Input Supply Fault
If the transmitter has shut itself off or is operating with an RF
Mute indication, and the Analog Input Supply Fault LED on the
Control front panel is illuminated RED, then one or more power
supplies has failed on this board. With the low voltage on,
measure the following voltages on the Analog Input board.
a. F3 should measure +22VDC, F2 should measure
–22VDC, and F1 should measure -+8VDC. If any one of
these supplies is not present, troubleshoot the low voltage
power supplies.
b. If all of these supplies are present, refer to the Trou-
bleshooting portion of Section J, Analog Input board.
6.4.14
A/D Converter Conversion Error
If the transmitter is operating but has 0W output, and the RF
MUTE and A/D Converter Conversion Error LEDs on the
Control front panel are illuminated RED, then the RF sample
required by the A/D Converter is not present or there is a fault
in the A/D conversion process.
a. With an oscilloscope, measure the RF squarewave signal
across R11, on the A/D Converter.
1. If the RF squarewavesignal is present across R11, refer
to the Troubleshooting section for the A/D Converter.
b. If no signal is present, check the RF signal at TP4 A/D
Phase on the Driver Encoder.
1. If the signal is present at TP4, then check the continuity
of the cable that connects the A/D Converter to the
Driver Encoder, through the Transmitter Interface.
c. If the RF signal is not present at TP4, check for an RF
signal across R106 on the Driver Encoder.
d. If there is no signal across R106, then check continuity of
the cable that connects the Driver Encoder to the RF
Splitter.
e. If the signal is present at R106 but not at TP4, refer to the
Troubleshooting section for the Driver Encoder.
6.4.15
A/D Converter Supply Fault
If the transmitter has shut itself off or is operating with an RF
Mute indicator lit, and the A/D Converter Supply Fault LED on
the Control panel is illuminated RED, then one or more power
supplies has failed on this board. With the low voltage on,
measure the following voltages on the A/D Converter board.
a. F1 should measure +22VDC, F2 should measure -
22VDC, F3 should measure+8VDC, and F4 shouldmeas-
ure -8VDC. If any one of these supplies is not present,
troubleshoot the low voltage power supplies.
b. If all of these supplies are present, refer to the Trou-
bleshooting portion of Section K, A/D Converter board.
6.4.16
Encoder Module/Cable Interlock
If the transmitter has shut itself off and the above LED is
illuminated RED on the Control front panel, an RF Amplifier(s),
Driver(s), or encoder cable(s) has been disconnected.
a. Open all of the front doors and observe DS2-Interlock 4,
DS3-Interlock 3, DS4-Interlock 2, and DS5-Interlock 1
on all Modulation Encoders and DS8-Interlock on the
Driver Encoder.
b. If any one of these LEDs are illuminated RED, the cause
of the fault has been detected by that circuit.
c. If no indicator is lit, then an open exists between the
different Modulation encoders or the fault sensing circuit
has failed.
1. Check the inputs and output of U3 on the Transmitter
Interface board to discover which signal is being inter-
rupted.
2. Ohmmeter check the appropriate cable if an input is
missing or low.
3. Refer to the Troubleshooting Section of the Controller
if the output of U3 is high.
6.4.16.1 Modulation Encoder Module/Cable Interlock
a. If DS2, DS3, DS4, or DS5 is illuminated RED on a
Modulation Encoder, refer to the Modulation Encoder
6-8 888-2339-002
WARNING: Disconnect primary power prior to servicing.