Motorola Pro Series Elite - Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

3-18 UHF (Band 1 and Band 2) Troubleshooting Charts
IF Signal at
L311?
No
RF Signal att
T301?
RF Signal at
C310?
No
RF Signal at
C307?
No
RF Signal at C301?
No or
Check harmonic filters L101 & L102 and ant. switches
CR101, CR102, L104
Check filter between C301 & C307;
program filter to schematic test freq
and check varactor voltages.
Inject RF into J101
Are varactor volt-
ages OK?
No
Yes
Check RF amp (Q301) Stage.
Check filter between C310 &
T301.
Yes
Check T301, T302, CR306,
R308, R309, R310
Yes
1st LO O/P OK?
Locked?
Yes
Check FGU
Yes
Trace IF signal from
L311 to Q302. Check
for bad XTAL filter.
No
Yes
Before replacing U301,
check U301 voltages;
trace IF signal path.
Yes
Check for 2.6 VDC
Is R5 present?
Check Q210, U201 (pin 48)
voltages and U247
No
No
No
Check U404 voltage. U404 can be
selected by MCU before replacing
U404.
Check varactor filter.
No
Yes
Yes
Yes
A
A
B
weak RF
Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)
Q302 collector OK?
IF signal present?