Rx Back-End-Poor Sinad Or No Audio (700-800 Mhz)-Part 2 Of 3 - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

Troubleshooting Charts: Flowcharts
5.6.37 RX Back-End—Poor SINAD or No Audio (700–800 MHz)—Part 2 of 3
Measure
control voltage
at TP6001
VCO <71.1
MHz?
VCO >75.6
MHz?
Figure 5-39. RX Back-End—Poor SINAD or No Audio (700–800 MHz)—Part 2 of 3
6881096C74-B
1
Freq
No
Yes
Freq
No
Yes
Inspect 2nd LO VCO
for missing parts or
varacter diode
TP6001 NOMINAL
VOLTS DC FREQ (MHz)
0.0
1.6
4.0
5.0
No
TP6001
= 5.0V?
Yes
No
TP6001
= 0.0V?
Yes
solder defect
Visual
No
inspection
OK?
Yes
Replace
D6051
MAEPF-27807-O
68.0
71.1
75.6
77.0
3
3
Repair defects
and/or replace
suspect parts
May 25, 2005
5-51