Rx If—Poor Sinad Or No Audio (380–470 Mhz And 450–520 Mhz)—Part 1 Of 2 - Motorola ASTRO XTL 1500 Detailed Service Manual

Troubleshooting Charts: Flowcharts
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 5-18. RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
6815854H01-A
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
Q5401
Voltage
No
Yes
Voltage
level of
No
Base
(pin 1)?
Yes
Inspect biasing
components and
check Voltage
Regulator U0950 for
normal operation
Replace
Q5401
June 15, 2005
5-27