Motorola APX 1000 Detailed Service Manual page 785

Troubleshooting Charts: TX Audio Error
External Mic Failure
TX Audio error
Examine Keypad and Main
Measure Audio at CODEC
Yes
Replace Backit Flex.
Test Internal Side MIC
External MIC
Board connectors.
Is Connector
Yes
Replace Connector
Demaged or Soldered
improperly
No
C6404 Capacitor
Yes
Audio signal present?
No
Measure MIC Bias at
R6404
No
4.5 < V < 4.9
Internal Side
No
MIC functional
Yes
Measure Audio Signal at Keypad
Board R2003
Yes
Audio Signal
present?
No
Replace Housing
and GCAI Flex
Check TX_DA thru R2817.
If no signal check CODEC
circuitry.
Inspect MIC Bias
circuit U6402 and
Supporting Circuitry
Follow TX Audio
Error - Side MIC
Failure
View SSI Signals at R2807
and R2808 using
Oscilloscope.
Yes
No
Is SSI Audio
Data Present
Yes
Parts Solder and
Placement Correct?
No
Replace parts
5-29
Check CODEC
or OMAP
Replace U6402