Motorola ASTRO Digital XTL 5000

6881096C74-B May 25, 2005
Troubleshooting Charts: Flowcharts 5-47
5.6.33 Poor RX Sensitivity or No RX Audio (700–800 MHz)—Part 1 of 2
Figure 5-35. Poor RX Sensitivity or No RX Audio (700–800 MHz)—Part 1 of 2
MAEPF-27875-O
Poor Rx
Sensitivity or no
Rx audio
Measure Transceiver
Sinad by injection
signal at antenna port
Yes
Yes
3kHz FM Deviation
1kHz Audio tone
Sinad
< - 119.1dBm?
Check RF level at
Mixer LO injection port
(U6251 Pin 3 side 1)
Receiver
is working
properly
No
Yes
Good?
1
Check Q6350,
Q6251, Q6252,
Q6253, Q6254
and make any
necessary repairs
No
Yes
RF level
at ~ 14dBm?
Check RX front-end
filter switching
voltage Table
Check Receiver
VCO troubleshooting
flowchart
(LO injection section)
No
Yes
RX Switching Voltages
Receiving at
700MHz Band
Receiving at
800MHz Band
Test Points
TP6256, 58,
60, 62
TP6255, 57,
59, 61
TP6254
LNA U6250
0V
7.6V
2V
3V
4V
7.6V
5V at Pin 1