Motorola Astro XTL 1500 - RX If-Poor SINAD or no Audio (380-470 Mhz and 450-520 Mhz)-Part 1 of 2

6815854H01-A June 15, 2005
Troubleshooting Charts: Flowcharts 5-27
5.6.16 RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
Figure 5-18. RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 2
Level
is -3dB
referenced to
R5412?
No
No
No
Yes
Measure the IF
signal level
(109.65MHz)
at C5403
Measure the IF
signal level
(109.65MHz)
at C5406
Check Y5400
Level
is +20dB
relative to the RF
input level
at C5406?
No
Yes
Voltage
level of 9.0V
at R5404?
Yes
Voltage
level of
0.7V at Q5401
Base
(pin 1)?
Yes
Measure the DC
Bias voltage level
on transistor
Q5401
Replace
Q5401
Inspect biasing
components and
check Voltage
Regulator U0950 for
normal operation
Inspect crystals and
matching networks for
missing components
and/or soldering defects
1