6871620L01-C
May 28, 2008
Troubleshooting Charts:
VOCON RX Audio
5-19
5.11 VOCON RX Audio–Page 1
Probe R1336 for
Frame Sync Signal,
Compare with
RX SAP waveform,
Trace 1
Frame
Sync
Present?
Replace
Mainboard
Probe R1338 for
Data, Compare
with RX SAP
waveform, Trace 2
Signal
Present?
THD <3%?
Clock
Present?
Probe R1335
for Clock Signal,
Compare with
RX SAP
waveform, Trace 3
Go to
RX RF
flowchart
Data
Present?
Check
Distortion of
Signal at C1355
Replace
Mainboard
Check Preamp
Output Signal at
C1355*
No
No
No
No
No
Yes
Yes
Yes
Yes
1
Yes
Bad SINAD
Bad 20db Quieting
No Recovered Audio
Inject Standard
Input into
RF Jack J1704
A standard input is an
RF signal with a 1 kHz
tone modulated with 3 kHz
deviation in a 25 kHz channel.
* Note: The Preamp output signal
should be checked differently
across C1355.
Summary of Contents for ASTRO XTSTM 4000
Page 1: ...COLOR CHORDS 7 ASTRO XTSTM 4000 Portable Radio Detailed Service Manual ...
Page 2: ......
Page 16: ...May 28 2008 6871620L01 C xiv Commercial Warranty Notes ...
Page 22: ...May 28 2008 6871620L01 C 1 6 Introduction Notes ...
Page 26: ...May 28 2008 6871620L01 C 2 4 Radio Power Notes ...
Page 56: ...May 28 2008 6871620L01 C 3 30 Theory of Operation Notes ...
Page 100: ...May 28 2008 6871620L01 C 6 8 Troubleshooting Waveforms Notes ...
Page 194: ...May 28 2008 6871620L01 C B 2 Motorola Service Centers Notes ...
Page 204: ...May 28 2008 6871620L01 C Glossary 10 Glossary Notes ...
Page 209: ......