9.2 - 14 MTM700 Mobile Radio / Detailed Service Manual TROUBLESHOOTING CHARTS (800MHz)
Receiver Troubleshooting (Sheet 1)
Is Pin 1 of the
Mixer U5002 at
3.3 Volts?.
GO to Synthesizer and
VCO Troubleshooting Chart.
Is there 3.3VDC at
C5031?
Check U5001 -
Pin 5 should be at 3.3V.
NO
YES
NO
YES
Is the signal
present?
Is the LO present at pin
3 of U5002?
Find and repair component or soldering problem in input path.
Check LNA U5002 which should give about 17dB of gain. Make
sure that U5002 pin 3 is at 1.9V. Replace LNA if necessary.
Also check FL5002, C5022, L5008, and C5027.
GO to Receiver IF
Troubleshooting Chart.
Check R5007 & L5004.
Is the LO present at
C5038?
NO
Check L5013, L5014,
L5017, C5028.
YES
NO
NO
YES
YES
Inspect RF input path. Input a strong RF
signal of about -40dBm at 860.525 MHz at
the RF connector and check signal at Pin4
of the Mixer U5002.
Tetra Com Script for Rx Test:
TEST_ENTER
DELAY 10
Check for "Radio HW is READY"
MODE IDLE
FREQ RX 860.525
L1TIMER ON
AVE 10
MODE RSSI
GO
Use STOP to terminate RSSI
reading
Failure:
Bit Error Rate @ -114dBm >3.5%
RSSI error > ±5dB
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