Motorola ASTRO Digital Spectra, Instruction Manual

Page: 78 / 114

56 6881086C22-B
TRC RX Audio Troubleshooting Chart
Setup radio for test.
Be sure all jumpers, switches,
and connectors are in correct
positions. Transmit on channel a
1kHz tone at 60%FSD (3kHz dev).
Refer to ASTRO Spectra
Detailed Service Manual
for correct operation
and troubleshooting.
Check/replace
U106.
Check VB, 9.6V and
FILTER_CLOCK signal;
also, be certain HY2
is inserted properly.
Check for
proper operation
of U124.
No
No
No No
No
No
Is 1kHz
signal present
at J1-42?
Yes
Yes
Yes
Yes Yes Yes
Yes
Yes No
No
active
high
active
low
Check 9.6V and VB;
also, check for
correct operation
of U111.
No
6
6
6
4
4
3
3
2
1
5
1
1
1
Is 1kHz
signal present
at U116-15?
Yes
(Tape Out)
2
TRC RX AUDIO
START
STOP
No
Is 1kHz
signal present
at J3-46?
Yes
3
No
Is 1kHz
signal present
at U114-13?
Yes
4
No
Is 1kHz
signal present
at U114-14?
Yes
5
Is 1kHz
signal present
at TP3?
Yes
6
Is 1kHz
signal present
at line 1
output?
Yes
Refer to
TRC board voltage
troubleshooting chart.
Check HY2 for
correct operation
and replace if
necessary.
No
Is
9.6V and VB
present?
Yes
Yes
No
Is
FILTER_CLOCK
signal a 0-5V square wave
at 110.4kHz?
Check for
correct operation
of U127 and U123.
Check/replace
U113 and U114.
Yes
Is
WL_MUTE
signal high?
No
No
Set S100
correctly.
Check 9.6V and VB,
also, evaluate
operation of U111 and
position of R545 wiper.
Are
RX_MUTE and
RADIO_SEL signals
low?
No
No
3
Is S100-1
off?
Check/replace
Q114 and/or Q115.
Is
signal present
at U111-1?
Yes
Is
signal at
secondary of
T100?
Check/replace
transformer.
Yes
Check/replace
U116 and U118.
Yes
No
Determine why U123
is holding signal
high and repair.
Yes
No
No
Determine why
U123 is holding
signal low and repair.
MAEPF-26155-O
Check / Replace
jumper
P102.
Check / Replace
Q117 and/or
Q118.
Check / Replace
Q102.
Troubleshooting
SPKR_Unmute
Operation
?
Is RX_Mute
low when
receiving
?
Is S100-1
off?
Determine why
U123 is holding
signal high, and
repair.
Set
S100
Correctly.
Place the jumper for
either active high or
active low operation.
Is jumper
P102 placed
appropriately
?
Does
voltage between
the collector of Q118
and R186 go from
5V to 0V when
receiving
?
Does
voltage between
the collector of Q102
and R189 go from
0V to 8V when
receivng
?
Is jumper
placed for active
high or active
low?
Does
voltage at R190
go from 0V to 5V
when receiving
?
Check / Replace
jumper
P102.