Transmitter Audio Troubleshooting - Motorola MTM800 User Manual

TROUBLESHOOTING CHARTS: 450-470MHz

Transmitter Audio Troubleshooting

Tetra Com Script for TX Audio Test
TEST_ENTER
DELAY 18
Check for "Radio HW is READY"
MODE IDLE
GEN_TONE OFF
DSP_LOOP ON
DSP_VOL 0
VOL_M 24
MICGA_M 27
MIC PHF
SPKR INT
Yes
Check stage
U0206-4
Failure:
No audio, low audio level or distortion > 2% at speaker output during
transmitter audio test.
PATS parameters AUD_LBACK_GAIN or AUD_LBACK_DIST failed
If receiver audio has not been checked, go to Receiver Audio Chart first.
Connect the speaker output on the radio's accessory connector via testbox
RLN4460B to the audio input on the IFR.
Connect the microphone input on the radio's accessory connector via testbox
RLN4460B to the audio output on the IFR.
Setup IFR to:
No System,
AF Test,
AF IN/OUT,
Gen 1 On,
AF 1 Frequency 1kHz
AF 1 Level 80mV
Distortion On
Run Tetra Com script for TX audio test
Measure the 1kHz audio signal with a scope
1kHz signal at
U0201 pin 13
Yes
1kHz signal at
Yes
No
0V DC at
U0201 pin 10
?
Yes
No
Check
transistor
Q0201
Yes
Yes
Start
No
Check components and connections
between U0201 pin 13 and accessory
connector pin 2
?
No
U0201 pin 14
?
1kHz signal at
U0201 pin 15
?
No
1kHz signal at
Check stage
U0206-4 pin 14
?
No
Before replacing U0203
1kHz signal at
check R0220, R0225,
FL0200 pin 17
C0221 and 3V DC at pin 8
?
Replace FL0200
Yes
9.3V DC
Replace
at U0201 pin 11
?
No
Check
transistor
Q0201
U0206-4
9.1 - 9
U0201