Vocon Rx Audio - Motorola ASTRO XTSTM 4000 Detailed Service Manual

Troubleshooting Charts: VOCON RX Audio
5.11 VOCON RX Audio–Page 1
Bad SINAD
Bad 20db Quieting
No Recovered Audio
Inject Standard
Input into
RF Jack J1704
* Note: The Preamp output signal
Check Preamp
Output Signal at
C1355*
No
Signal
Present?
Yes
Check
Distortion of
Signal at C1355
No
THD <3%?
Yes
1
6871620L01-C
A standard input is an
RF signal with a 1 kHz
tone modulated with 3 kHz
deviation in a 25 kHz channel.
should be checked differently
across C1355.
Probe R1338 for
Data, Compare
with RX SAP
waveform, Trace 2
Mainboard
flowchart
Probe R1335
for Clock Signal,
No
Data
Compare with
Present?
RX SAP
waveform, Trace 3
Yes
Replace
Go to
RX RF
5-19
Clock
No
Present?
Yes
Probe R1336 for
Frame Sync Signal,
Compare with
RX SAP waveform,
Trace 1
Frame
Yes
Sync
Present?
No
Replace
Mainboard
May 28, 2008