6.4
Symptom: Transmitter will not turn
on - one or more ColorStat™ panel
indicators are illuminated RED.
6.4.1
Possible Causes
See the “Troubleshooting ColorStat™ Panel Indicator Faults”
paragraph in this section.
6.5
Symptom: Transmitter will turn ON
but immediately turns OFF - one or
more ColorStat™ panel indicators il-
luminate RED. The transmitter may
try to turn on twice and a fault indi-
cator illuminates AMBER then RED.
6.5.1
Possible Causes
In the case of the Overcurrent, Overdrive and Underdrive over-
loads, the transmitter will try to restart one time before indicat-
ing a fault. This indicates that the fault still exists and must be
repaired before the transmitter will become operational. See the
“Troubleshooting ColorStat™ panel Indicator Faults” para-
graph in this section.
6.6
Symptom: Transmitter turns On
(LOW, MEDIUM or HIGH buttons
illuminate) but there is no power out-
put and no PA current is indicated.
Supply voltage is indicated on the
multimeter.
6.6.1
Possible Causes
6.6.1.1
PA Turn-Off Command Given To Transmitter
The PA Turn-Off command will allow the PA Power Supply to
energize, but will not allow any of the RF amplifiers to be turned
ON to produce power output. To check for a PA Turn-Off
command, open the Center Control Compartment door and
observe section DS1-9 on the Modulation Encoder. If the trans-
mitter PA Power Supply is energized and DS1-9 is illuminated
RED, a PA Turn-Off command is being given to the transmitter.
Check the following items for a PA Turn-Off command:
a. PA Turn-Off Switch S2 on Controller set to OFF Position.
Check to make sure this is set to the ON (down) position.
b. External PA Turn-Off Circuit Activated
The External Interface allows the use of an External PA Turn-
OFF command for customer applications such as Day/Night
switching on a Phasor. If this feature is connected, make sure
that the device associated with the PA Turn-Off is not at fault.
To check, remove the wire connected to the Customer Remote
control terminal strip TB1-22.
6.6.1.2
Type 4 or Type 5 Fault
Regulator faults that occur on the Analog to Digital Converter
and the Analog Input Board will generate a Type 4 fault and
cause a PA Turn-Off command. A Type 5 fault is generated by
the Analog to Digital Converter conversion error fault circuit
and will also produce a PA Turn-Off command. If any of these
fault indicators are illuminated on the ColorStat™ panel, refer
to the “Troubleshooting ColorStat™ panel Indicator Faults”
paragraph in this section.
6.6.1.3
Power Output Is Set To Zero
No transmitter output power and the PA OFF LED segment
DS1-9 on the Modulation Encoder is not illuminated, indicates
that the output power has been lowered to zero. Press the RAISE
button to see if power begins to rise. If it does, hold the RAISE
button until the desired output power is reached. Reset the other
power levels to the desired output power. A power reset nor-
mally occurs only when the battery backup power supply on the
Controller
discharges and the transmitter AC power has been off for over
one hour. Replace the batteries and check the +5V “B” supply
on the Controller if this is a common occurrence.
If the power is zero and cannot be increased by the RAISE
control, investigate the power control circuitry on the Analog
Input Board and the Controller. See the specific section for each
of these boards for circuit information.
6.7
Symptom: Transmitter is running,
but power is lower than normal.
6.7.1
Possible Causes
6.7.1.1
Power Reduction Circuitry Activated
a. ANTENNA LED on the ColorStat™ panel is RED. This
indicates a VSWR problem in the load, phasor, combiner
or antenna system. Press the RESET button on the Col-
orStat™ panel. If the LED turns GREEN, press RAISE
and set power back to normal. This indicates that the
VSWR problem is not active anymore. If the LED will
not reset GREEN, the problem is still active and must be
investigated. If further testing does not reveal a problem
in the RF load that the transmitter is connected to, inves-
tigate components in the phase angle detector on the
Output Monitor. refer to SECTION H, Output Monitor,
for additional information.
b. BANDPASS LED on the ColorStat™ panel is RED,
power cannot be raised. This indicates a VSWR problem
in the matching network between the power amplifier and
output network stage in the transmitter. Likely causes are
defective vacuum capacitors. If capacitors in the bandpass
circuit are not defective, investigate components in the
phase angle detector(s) on the Output Monitor. Refer to
SECTION H, Output Monitor, for additional information.
Section VI - Troubleshooting
Rev. R: 11-11-96
888-2297-002
6-7
WARNING: Disconnect primary power prior to servicing.
