Service Manual

75
Chart 12—VRS ICM Audio Failure
IN-CAR-MONITOR AUDIO ISSUES
Ye s
Ye s
Ye s
Ye s
Ye s
Ye s
No
Ye s
No
Ye s
Ye s
No
No
No
No
No
No
Ye s No
Verify that the VRS750
dip switches are set
for normal operation.
PTT the mobile's local
mic and talk into it.
Is
audio present at
C134?
Refer to the
Base-to-Portable
troubleshooting chart.
Is audio
present @ pin 3 of
U101.?
Check the mobile
and its mic
connections.
Check U104 and
adjust R148 if
necessary.
Check and/or
replace U101.
Check and/or
replace Q114.
Activate the
VRS750.
Is "VRS
BOTH" displayed
briefly?
During
Base-to-Portable
communications, is audio heard
@ the portable?
Check C185 and C166 to
make sure they have not
been shorted to ground.
Verify that the
MOBILE_MIC_HI line in
the mobile to VRS is ok.
Is audio
present @ pin 1 of
U101?
Is audio
present @ pin 15 or
U101?
Is pin 9 of
U101 a logic HIGH -
9.6VDC.?
Is pin 10
of U101 a logic HIGH -
9.6VDC.?
Check and/or
replace U101.
Check and/or
replace Q106.
Is
audio present @
J30-19?
Is
there continuity
between J30-19 and
J20-7 of the flex
cable?
Check and/or
replace C104.
Replace the
transceiver.
Replace the flex
cable.