May 28, 2008
6871620L01-C
5-6
Troubleshooting Charts:
DC Supply Failure
5.4
DC Supply Failure–Page 1
NOTE:
Since the failure of a critical voltage supply might cause the radio to automatically power
down, supply voltages should first be probed with a multimeter. If all the board voltages
are absent, then the voltage test point should be retested using a rising-edge-triggered
oscilloscope. If the voltage is still absent, then another voltage should be tested using the
oscilloscope. If that voltage is present, then the original voltage supply in question is
defective and requires investigation of associated circuitry.
Voltage =
5 Vdc
Yes
Problem With
DC Power
Disctribution
Check voltage at
pin 4, U1101
Voltage =
Check continuity of
Fuse F901
No
Fuse OK?
Replace Fuse
No
Yes
Check battery
connection for
good contact
Yes
Check voltage at
pin 5, U1101
Check D4,
VR1209, R1133
C1141
No
Components
OK?
Replace problem
components
No
Yes
Replace U1101
1
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: ......