Motorola Astro XTL 1500 - Figure 5-20. RX Back-End-Poor SINAD or no Audio (380-470 Mhz and 450-520 Mhz); Figure 5-21. RX Back-End-Poor SINAD or no Audio (380-470 Mhz and 450-520 Mhz); Figure 5-22. RX Back-End-Poor SINAD or no Audio (380-470 Mhz and 450-520 Mhz); Part 2 of 3

June 15, 2005 6815854H01-A
5-30 Troubleshooting Charts: Flowcharts
5.6.19 RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—
Part 2 of 3
Figure 5-21. RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 3
No
3
3
1
R5013
= 5.0V?
No
Yes
Yes
R5013 = 0.0V?
No
Yes
Freq 2nd LO
VCO <107.4
MHz?
No
Yes
Measure
control voltage
at R5013
Inspect 2nd LO VCO
for missing parts or
solder defect
Yes
No
Visual
inspection
OK?
Repair defects
and/or replace
suspect parts
Replace
varactor diode
D6051
R5013
VOLTS DC
NOMINAL
FREQ (MHz)
0.0
1.6
4.0
5.0
68.0
71.1
75.6
77.0
Freq 2nd LO
VCO <107.4
MHz?