Dc Supply Failure - Motorola APX 7000 Detailed Service Manual

Troubleshooting Charts: DC Supply Failure
5.4

DC Supply Failure

5.4.1 DC Supply 5V Failure
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.
Remove shield SH14
Check voltage Pin 5 of
U200
No
Check Voltage Pin 4 of
Voltage 5V
Yes
Check for open in the
branch, to the section you
are troubleshooting.
Remove shield SH9
Check Voltage Pin 2 Q201
Check Fuse F200
U200
Yes
Voltage 7.5V
Replace U200
No
Yes
Check
Voltage 7.5V
Voltage Pin 1 Q202
No
Check E201
Check M101
Yes
Check Supply
Components
Check for open between
OK?
M101 and Pin 2 Q201
No
Replace
Problem
Component
Check components
Yes
Voltage 3.6V
Q202,R202,R201 and
No
Check 40 Pin connector
P101 to J1001 Pin 37 for
an open
Yes
Replace 40 Pin
Open found?
connector
No
Refer to Vocon
troubleshooting guide for
the 3.6V SW1 supply.
Component
OK?
Q201
No
Replace
Problem
Component
5-15