Motorola MTM700

9.2 - 16 MTM700 Mobile Radio / Detailed Service Manual TROUBLESHOOTING CHARTS (800MHz)
Tx Frequency Generation Troubleshooting
Is the TX RF present
at C5634 @ -4dBm?
Typical Bias voltages for Q5601:
• Base 2.1V,
• Collector 4.1V, and
• emitter 1.5V.
NO
NO
YES
Is the TX REF
present at
TP5702 @ -
15dBm?
Is the Voltage at
C5609 about 2.3V?
NO
YES
Run Tetra Com script for TX FGU
Test.
Measure RF levels and frequencies
with the 50 Ohm RF probe.
Measure DC levels with a multimeter.
Check C5706, C5707,
C5709, R5709, L5703.
Check Loop Filter; C5609,
R5653, R5652, C5653, C5655,
L5607.
YES
Is TX RF present at
C5641 @ 0dBm?
NO
Continue to check for de-
fects in Escort Circuit.
GO to Synthesizer and
VCO trouble shooting Chart.
GO to the LNODCT trouble-
shooting Chart if radio does not
transmit.
NO
Is the TX REF
present at pin
10 of U5701?
YES
Is the
Resonator
OK?
NO
NO
NO
YES
Is C5640 @
5V?
NO
YES
Are Bias volt-
ages
present?
Typical Bias voltages for Q5621:
• Base 0.5V,
• Collector 3.1V, and
• emitter 0V
Rework bias
components
Check Q5352,
Q5301, and bias
components.
Fix Resonator.
Rework bias com-
ponents.
Check that there is 5V at the collector
of Q5352, Pin 48 of U5331 should be
0V. Check Q5301, R5722, R5723.
YES
Is Pin 20 of
U5701 @
5V?
NO
Check that the voltage at pins 14 and 16
of U5701 is at 5V. Check surrounding
components. Replace U5701 if no prob-
lems found.
Is there 0dBm
RF at Pin 4 of
U5701?
YES
NO
YES
Tetra Com Script for TX FGU Test:
TEST_ENTER
DELAY 10
Check for "Radio HW is READY"
MODE IDLE
INTR DIS
FREQ TX 869.925
L1TIMER ON
TX POW 4
RFTON ATT 0.5
RFTON FRQ 0
RFTON CHN I
FEEDBACK OPEN
MODE RFTONE
Use MODE IDLE to terminate transmit
mode