Receiver Audio Troubleshooting - Motorola MTM800 User Manual

9.1 - 8

Receiver Audio Troubleshooting

Tetra Com Script for RX Audio Test
TEST_ENTER
DELAY 18
Check for "Radio HW is READY"
MODE IDLE
DSP_LOOP OFF
GEN_TONE 1000
DSP_VOL -5
VOL_M 27
SPKR INT
If no 1kHz signal at
handset audio output,
check stage U0206-2
Check collector of
transistor Q0200 and
connected resistors.
Before replacing check
mute to low.
Failure:
No audio or low audio level at speaker output or handset audio output.
High distortion at speaker output or handset audio output.
PATS parameters AUD_LBACK_GAIN or AUD_LBACK_DIST failed.
Start
Connect the speaker output on the radio's
accessory connector via testbox RLN4460B to the
audio input on the IFR.
Setup IFR to:
No System,
AF Test,
AF IN/OUT,
Gen 1,2,3 Off,
Distortion On
Run Tetra Com script for RX audio test
Measure the 1kHz audio signal with a scope
1kHz signal
at FL0200 pin 2
Yes
1kHz signal
at U0201 pin 5
1kHz signal
at U0201 pin 4
Yes
No
> 8.5V DC at
U0205 pin 8
Yes
If no 1kHz signal at
speaker output, check
R0244, R0245, C0227,
13.2V at pin 7 before
replacing U0205.
No
Before replacing
FL0200 check for
activity on pin 7,8,11,13
?
If no 1kHz signal at
accessory connector pin
11, check stage U0206-1
No
Before replacing U0204
check resistors R0221,
R0228 and 3V DC at pin 8
?
No
0V DC
at U0201 pin 9
?
9.3V DC
at U0201 pin 16
?
Replace
U0201
TROUBLESHOOTING CHARTS: 450-470MHz
No
Check
transistor
Q0203
?
Yes
No
9.3V DC supply failure!
Go to DC Supply Chart
?
Yes