User Manual

SERVICING
5-4
June 1997
Part No. 001-3492-001
5.4.5 MODULATION INPUT
1. Check for audio/data signals at J201, pin 6, Y800,
pin 1 and A840, pin 3.
5.4.6 TCXO
1. Check Y800, pin 1 for 2.5V DC ±1%.
2. Adjust Y800 to set the transmitter to the frequency
of operation.
3. If the frequency cannot be set to the frequency of
operation, replace the TCXO.
Figure 5-2 TRANSMITTER SERVICING
START
MEASURE
CURRENT AND
OK
?
NO
YES
MEASURE RF
WATTS
?
CHECK DEVIATION
TRANSMITTER
OK
OK
?
OK
?
NO
NO
NO
YES
YES
YES
WIRE HARNESS CONNECTIONS
CHECK FUSES AND
CHECK AUDIO
CHECK TCXO
ADJUST OR
CHANGE TCXO
OFF FREQ
5
VOLTAGES
OUTPUT POWER
(SECTION 5.4.6)
CIRCUITS
CHECK FREQUENCY
(SECTION 5.4.7)
Y800
CHECK Q500
CHECK DRIVER
OK
?
NO
YES
CHECK A840
REFER TO
SECTION 5.4.2
OK
?
NO
YES
REFER TO
CHECK
POWER MODULE
SECTION 5.4.4
CHECK U510
OK
?
NO
REFER TO
CHECK
ANTENNA SWITCH
SECTION 5.4.5
CHECK
CR540/541