Rx If—Poor Sinad Or No Audio (380–470 Mhz And 450–520 Mhz)—Part 1 Of 2 - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

5-30
5.6.16 RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
Measure the IF
signal level
(109.65MHz)
at C5406
Level
is -3dB
referenced to
R5412?
Yes
Measure the IF
signal level
(109.65MHz)
at C5403
Level
is +20dB
relative to the RF
input level
at C5406?
Yes
1
Figure 5-20. RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
May 25, 2005
No
Check Y5400
Measure the DC
No
Bias voltage level
on transistor
level of 9.0V
at R5404?
0.7V at Q5401
Inspect crystals and
matching networks for
missing components
and/or soldering defects
Troubleshooting Charts: Flowcharts
Q5401
Voltage
No
Regulator U0950 for
Yes
Voltage
level of
No
Base
(pin 1)?
Yes
Inspect biasing
components and
check Voltage
normal operation
Replace
Q5401
6881096C74-B