Motorola APX 7000 Detailed Service Manual page 118

5-14
Power-Up Failure – Low VCC_SW_1.875 Voltage
Low VCC_SW_1.875
Voltage
Measure Radio
Current
Is Standby
Current more
than 15mA above
Average
No
Measure SW_B+
Voltage at R6549
Voltage =
SW_B+
Yes
Measure Voltage
at R6431 on
VCC_5.0A Side
Yes
4.8 < V < 5.2?
No
Proceed to Low
LDO8 VCC_5.0A
Voltage Flow
Chart
Yes
Board has a short,
Replace VOCON
Proceed to
No
Incorrect B+
Voltage
Measure Voltage
at R6431 on
BGAP_COMP
Side
Measure Voltage
2.2 < V < 2.7?
at R6420
No
Replace VOCON
2.2 < V < 2.7?
Yes
Inspect U6508 and
All Supporting
Circuitry
Troubleshooting Charts: Power-Up Failure
Inspect and Repair
Yes
U6409 and
Supporting
Circuitry
No
Board
Are Parts Solder
No
Connections and
Placement Correct
Yes
Replace VOCON
Board
Replace or Repair
Part/s