Motorola MTM700, Detailed Service Manual

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TROUBLESHOOTING CHARTS (800MHz) MTM700 Mobile Radio / Detailed Service Manual 9.2 - 11
Low Tx Power Troubleshooting
Is Tx current
greater than
0.8 Amps?
YES
YES
• Check C6840 to see if the 5V_TX_SW
is present
• Check Bias components for Q5804
• Check 5V_TX supply from U0304
• Check 3V_TX supply from U0307
OK
Tune output power
NO
NO
NO
NO
Check Components in PA matching Networks,
especially:
Final device: C5439, C5432, C5437 C5434 C5439
MRF1517: C5426, C5427
Driver IC: C5416
Is the voltage at
L5452 @ 1.7V?
YES
Is the power
> 2.5Watts?
Check Harmonic filter components for
placement and good solder contacts,
especially: FL5451, L5461, & L5462
Is the power
> 2.5Watts?
Repeat Low Tx Power Troubleshooting
Chart
OK
Tune output power
NO
YES
GO to PA Bias
Troubleshooting Chart
Is there 0dBM
RF at 806 MHz
at TP5401?
GO to LNODCT
Troubleshooting Chart
Tetra Com Script for Tx Power Test:
TEST_ENTER
DELAY 10
Check for “Radio HW is Ready”
MODE IDLE
INTR EN
FREQ TX 869.925
L1 TIMER ON
TXPOW 6
MODE TXNDC
Use MODE IDLE to terminate tranmit
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.
Setup IFR:
• Select high power input.
• Select No System,
• Select TX Test,
• Select TX Frequency 869.925 MHz
• Use Spectrum Analyser
• Set Reference Level to 40dBm.
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 RF output power.
Too high RF output power.
PATS parameters ADJ_PWR1-5, ATT_SP1-5,
DC_CUR1-5, TX_PWR_F1-5 failed.
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