TTU500FA TROUBLESHOOTING CHART
PROBLEM
INDICATORS
CAUSE
SOLUTION
3
6
6
LOW OUTPUT
POWER
AMPLIFIER
UNLIT
RF POWER
<100%
Output transistor failure
in 300W Amplifier of
500W drawer indicated
Replace failed 500W
Amplifier drawer, 300W
Amplifier Assembly or
transistor.
POWER SUPPLY
UNLIT
RF POWER
<100%
32V Power Supply
failure in 500W drawer
indicated
Replace failed 500W
Amplifier drawer or 32V
power supply.
LOW OUTPUT
POWER OR
DISTORTED
OUTPUT
No Fault indicated
Output Power
Calibration is incorrect
See Section 3.5.
Modulator malfunction
Replace modulator.
High loss in one of the
modules
Test each module for
correct gain/loss. See
Signal Flow Diagram
(Fig 3
6
2) for gains/
losses.
Precorrector improperly
adjusted or not active
See Section 3.6.
NO VISUAL
OUTPUT
(AURAL OK)
No Fault indicated
Modulator failure
Replace modulator.
Bad cable
Check rear panel visual
loop-thru cable.
NO AURAL
OUTPUT
(VISUAL OK)
No Fault indicated
Modulator failure
Replace modulator.
Bad cable
Check rear panel aural
loop-thru cable.
