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

June 15, 2005 6815854H01-A
5-28 Troubleshooting Charts: Flowcharts
5.6.17 RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 2
Figure 5-19. RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 2
Level
is -3dB
referenced to
C5403?
No
No
Yes
Measure the IF
signal level
(109.65MHz)
at C5403
Measure the IF
signal level
at U5400-3
Check Y5401
No
Yes
U5400-4 > 3V
and U5400-5 < 0.2V
(Without pre-amp)
U5400-4 < 0.2V
and U5400-5 > 3V
(With pre-amp)?
Same as level
at U5400-3
(Without pre-amp)
or -10 dB referenced
to level at U5400-3
(With pre-amp)?
Yes
Refer to
troubleshooting
flow digram for
Receiver Back End
Measure the DC
voltage level
at U5400-4
and U5400-5
Replace
U5400
Troubleshoot
Q5402 and
associated
circuitry
1