
75
Chart 12—VRS ICM Audio Failure
IN-CAR-MONITOR AUDIO ISSUES
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
No
Yes
Yes
No
No
No
No
No
No
Yes
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.
Summary of Contents for VRS750
Page 1: ...1 VRS 750 Vehicular Repeater System Detailed Service Manual ...
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