Motorola APX 5000 Service Manual page 113

Troubleshooting Charts: Power-Up Failure
Power-Up Failure – Low LDO3 V_1.55 Voltage
Low LDO3 V_1.55
Voltage
Measure Radio
Current
Is Standby
Current more
than 15mA above
Average
Inspect R6561
Connection
Is R6561
Soldered
Properly
Measure
V_2.23 at
R6513
2.0 < V < 2.4?
Likely MAKO
Problem, Replace
VOCON Board
Yes
Board has a short,
Replace VOCON
No
No
Correct R6561
Soldering
Yes
Proceed To Low
No
V_2.23 Voltage
Flow Chart
Yes
Synopsis
This failure specifically refers to LDO3
but this flow chart can be used to
diagnose LDO2. All LDOs mentioned
above are fed from the same source
and have very limited differences.
Please refer to schematic and theory of
operation section for differences.
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