Motorola Mtx Series Detailed Rev 6881088c46 E Manual
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Page 91
Chapter 9 VHF Troubleshooting Charts 9.1 Troubleshooting Flow Chart for Controller MCU Check Power Up Alert Tone OK? Speaker OK? U409 EXTAL= 7.3728 MHz? U3701 Pin 19 16.8 MHz 5V at U3711? 3.3V at U3201? U409 Reset Pin 94 High? MCU is OK Not able to pro- gram RF Board ICsBefore replacing MCU, check SPI clock, SPI data, and RF IC select Replace Speaker Read Radio OK? Check Setup Reprogram the correct data. See FGU Troubleshooting 7.5V at Pin 3/5 U3711? 7.5V at Pin 1 U3201Check Q400...
Page 92
December 26, 2003FMR-2045A-2 92VHF Troubleshooting Charts: Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) 9.2Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) Bad SINAD Bad 20dB Quieting No Recovered AudioSTART Audio at pin 8 of U3220?Check Controller (in the case of no audio) or else go to “B”Ye s No Spray or inject 44.85MHz into XTAL Filter Y3200 Audio heard?BYe s No Check 2nd LO (44.395MHz) at C3274 LO Present?BYe s Voltages OK? Biasing ok? Check circuitry around U3220. Replace...
Page 93
FMR-2045A-2December 26, 2003 VHF Troubleshooting Charts: Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) 93 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) IF Signal at L3200? No RF Signal at T3301? RF Signal at R3313? No RF Signal at C3306? No RF Signal at C3302? No or Check harmonic filter L3531 and L3532, C3532 and antenna switches D3521, D3551, L3551, R3551, C3551, C3552, and L3552 Check filter between C3302 & C3306; pro- gram filter to schematic test freq and check...
Page 94
December 26, 2003FMR-2045A-2 94VHF Troubleshooting Charts: Troubleshooting Flow Chart for Transmitter 9.3 Troubleshooting Flow Chart for Transmitter START No Power Is There B+ Bias for Ant switchCheck Q3561 Is Current OK?Is Control Voltage high or low?Check PCIC 1. Check Pin Diodes 2. Check Harmonic Filter Inspect/Repair Tx. Output Network Is Power OK? Done Check Drive to Module Is Drive OK? Troubleshoot VCO Inspect PA Network/ Check power out of U3501 at Cap C3512 Is Power OK? Replace U3501...
Page 95
FMR-2045A-2December 26, 2003 VHF Troubleshooting Charts: Troubleshooting Flow Chart for Synthesizer 95 9.4 Troubleshooting Flow Chart for Synthesizer 5V at pin 6 of D3701 Is information from µP U409 correct? Is U3701 Pin 18 AT 4.54 VDC? Is U3701 Pin 47 AT = 13 VDC Is U3701 Pin 19 4.3 VDC in TX? Sta rt Visual check of the Board OK?Correct Problem Check 5V Regulator +5V at U3701 Pin’s 13 & 30? Is 16.8MHz Signal at U3701 Pin 19? Check Y3761, C3761, C3762, C3763, D3761 & R3761 Are signals at Pin’s...
Page 96
December 26, 2003FMR-2045A-2 96VHF Troubleshooting Charts: Troubleshooting Flow Chart for VCO 9.5Troubleshooting Flow Chart for VCO START No LO? Tx Carrier? VCO OK Check R3829 TRB = 3.2V?Pin 10 >1V? L3831, L3832, L3833 O/C? Change L3831, L3832 Change U3801 AUX 3 High? Check U3701 Pin 2 for 3.2V Pin 19 =0V AUX 3 Low? Change U3801 V ctrl 0V or 13V?L3821, L3822, L3823 Open Circuit? Change U3801 Change L3821, L3822, L3823, andL243 Change U3701 Check for faulty parts or dry joints of...