Trc Local Tx Troubleshooting Chart - Motorola ASTRO Spectra Instruction Manual

TRC LOCAL TX
Check control head and
No
mic operation as specified
in ASTRO Spectra Detailed
Service Manual.
1
No
Check/replace
U110 and U105
2
No
Check/replace
U101.
3
Check/replace No
U106.
4
Check/replace No
U105.
4
6881086C22-B
Set up
radio for test.
Inject a 90mVrms
1kHz signal into
the mic input of
the control head.
1
Is 1kHz
signal present
at C605?
Yes
2
Mic Hi
Is 1kHz
Check/replace
signal present
U113 and U114.
at J1-23?
Yes
3
4
VU Meter
Is 1kHz
signal present
at J6-1?
Yes
4
(Tape Out)
Is 1kHz
signal present
at J3-46?
Yes
Is 1kHz
signal present
between R556
and R559?
Yes
Is 1kHz
signal present
at U114-13?
Yes
4
Check for Is 1kHz
No
signal present
proper operation
of U124. at U114-14?
Yes
5
Is
Is 1kHz
Yes
WL_MUTE
signal present
signal high?
at TP3?
Yes
No
6
Determine why
Is 1kHz
U123 is holding
at line1
signal low and
output?
repair.
Yes
4
STOP
Check VB, 9.6V and
Is
No
FILTER_CLOCK signal,
9.6V and VB
also, be certain HY2
present?
is inserted properly.
Yes
Is
FILTER_CLOCK
signal a 0-5V square
wave at
110.4kHz?
Yes
Check 9.6V and VB,
Check HY2 for
No also, evaluate
correct operation and
operation of U111 and
replace if necessary.
position of R545 wiper.
5 3
Check 9.6V and VB;
Is
No
No also, check for
signal at
correct operation
U111-1?
of U111.
Yes
6
Is
Check/replace
No
signal at
Q114 and/or
secondary of
Q115.
T100?
Yes
6
Check/replace
transformer.
6

TRC Local TX Troubleshooting Chart

Refer to TRC
No
Board Voltage
Troubleshooting
Chart.
Check for
No
correct operation
of U127 and U123.
3
MAEPF-26156-A
55