Motorola MTM700

TROUBLESHOOTING CHARTS (800MHz) MTM700 Mobile Radio / Detailed Service Manual 9.2 - 13
LNODCT Troubleshooting
Is the LNODCT
buffer output,
measured at
C5806, at about
10dBm?
Check signals on ADDAG IC U5802
and if necessary change IC U5802.
2.4MHz Clock @ Pin 34.
Pulsed data with period of 56.7ms @ Pin 5-8.
GO to Tx Frequency
Generation Trouble-
shooting Chart.
Are both splitter
outputs, meas-
ured at C5813
and C5803, about
0dBm?
Fix problem with RF path to Phase split-
ter or replace phase splitter.
NO
NO
YES
YES
NO
YES
NO
Is RF at
C5804 about
-5dBm?
Is the RF Feed-
back signal
present at C5862
and C5863 @
0dBm?
Check signals on LNODCT IC U5803
and if necessary change IC.
ASW is low during TX slot.
0dBm RF @ Pins 51 &52.
Fix problem with LNODCT buffer amplifier
Q5801.
Bias voltages for Q5801 are:
• Emitter 0V,
• Base 0.7V, and
• Collector 4.3V.
Q5801 supply TXH at C5830 should be 5V; If not
check Q5352 and Q5301.
Check L5812, R5453, R5454,
R5455
Tetra Com Script fo Tx Power Test :
TEST_ENTER
DELAY 10
Check for "Radio HW is READY"
MODE IDLE
INTR EN
FREQ TX 869.925
L1TIMER ON
TXPOW 6
MODE TXNDC
Use MODE IDLE to terminate
transmit mode.
Connect the radio's accessory connector to the Tetra Com
interface.
Connect the radio's antenna connector to the high power
RF output on the IFR.
Run Tetra Com script for TX Power Test.
Measure RF levels with a high impedance RF probe and a
millivoltmeter.
Measure DC levels with a multimeter.
Failure:
No or low LNODCT output signal level.
START