Motorola Cm Radio Vhf2 Hp Information Manual
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Chapter 3 TROUBLESHOOTING CHARTS This section contains detailed troubleshooting flowcharts. These charts should be used as a guide in determining the problem areas. They are not a substitute for knowledge of circuit operation and astute troubleshooting techniques. It is advisable to refer to the related detailed circuit descriptions in the theory of operation sections prior to troubleshooting a radio. Most troubleshooting charts end up by pointing to an IC to replace. It is not always noted, but it is good practice to verify supplies and grounds to the affected IC and to trace continuity to the malfunctioning signal and related circuitry before replacing any IC. For instance, if a clock signal is not available at a destination, continuity from the source IC should be checked before replacing the source IC.
3-2TROUBLESHOOTING CHARTS 1.0 Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2) Problem in 12 KHz and 25 KHz channel spacing 9V on R310 (LNA) OK?Check RX_ENNoGo to DC Section Ye s RX_EN ON ?NoCheck Q306, Q300 and U403Ye s START LOC_DIST ON?Check Q304, D305 and U403 LO POWER OK ? Go to SYN Section Ye s Ye s No No Go to A Ye s 3 V to U301 Okay ?No Check LOC_DIST Go to DC Section Ye s Check D301-304 Replace IF Filters( FL304, FL301) If problem in 25 KHz spacing Check TP1 Check 5V on R336 5V (IF AMP) OK ?Go to DC SectionYe s NoCheck 3V on R338 No
Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2) 3-3 1.1Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) 3V (IFIC -Vcc) OK ? Installation OK ? Ye s Ye s No No A From Check visually all receiver components installation ? Inject - 40dBm (CW) to RF connector Check Power on C332 RF Power > -28 dBM?Ye s NoCheck Power on C336 Go to DC Section Check the component Antenna to Mixer circuitry problem Replace Q303, Q301 Check passive componentsRF Power > -28 dBM?Ye s NoReplace Q305, Q300, U302 Check passive componentsCheck Y301 44.395 MHz Y301 OK?Ye s NoReplace Q302, Y300 Check D301 - 304 Replace Y301 3V to U301 OK?Ye s NoReplace U300Go to DC Section
3-4TROUBLESHOOTING CHARTS 2.0 Troubleshooting Flow Chart for 45W Transmitter (Sheet 1 of 3) START Ye s No Check components between Q100 and RF output, Antenna Switch D104, D103, VR102 and Q106 No or too low power when keyed Current increase when keyed? Check power settings, tuning & components between U103 Pin 3 and ASFIC Pin 6 before replacing ASFIC Control Voltage at TP150 >4Vdc?Check PA Stages >4A Voltage U103 pin 5 = 4.6V? U103 Pin 3 1.8Vdc Check 9.3V Regulator U501 Ye s Ye sNo No Ye sCheck U103 Check forward Power Sense Circuit No Short U100 Pin 3 to ground Voltage at TP150 rises?Check PA Stages Check Forward Power Sense Circuit Ye s No >500mA &
Troubleshooting Flow Chart for 45W Transmitter (Sheet 1 of 3) 3-5 2.1Troubleshooting Flow Chart for 45W Transmitter (Sheet 2 of 3) Ye s Check bias tuning before replacing U504 Check PA Stages No or too low power when keyed DC Voltage at Q101 base=0? DC Voltage at U103 Pin 8 Check U510 Check resistive network at Pin 9 and 10 of U103 before replacing U101 DC Voltage at C1095 Check Final PA Stages ASFIC U504 Pin 5 2-3V Check components be- tween ASFIC and Q105 before replacing Q105 DC Voltage at U103 Pin 10=8.9V Check Q101, R122, R197, R153, R136, R165, R168, Check U103 before re- placing U101 No No Ye s >5V 2 to 5V 2-3V Ye s No 0V
3-6TROUBLESHOOTING CHARTS 2.2Troubleshooting Flow Chart for 45W Transmitter (Sheet 3 of 3) No Ye s Ye sNo Check Final PA Stage PA_Bias Voltage at R134 RF Voltage after C1044 >100mV? Voltage across R122 >2V? RF Voltage Q105 gate >1V? RF Voltage Q100 gate >1.5V? Check components between Q100 & antenna connector Replace Q100 Check FGU Check components between C1044 & C1117 Check components between C1117 & Q105 Check components between Q105 & Q100 No No Ye s Ye s 1-4VdcSupply Voltage Check components between ASFIC & Q100 before re- placing Q100 RF Voltage after C1044 >100mV? Check Bias Tuning before replacing ASFIC U504 Ye s No0V
Troubleshooting Flow Chart for Synthesizer3-7 3.0 Troubleshooting Flow Chart for Synthesizer +5V at U200 Pins 13 & 30? 5V at pin 6 of D200 Is information from µP U403 correct? Is U200 Pin 47 = 13VDC? Is U201 Pin 19 4.5 VDC in TX? (at VCO section) Sta rt Visual check of the Board OK?Correct Problem Check 5V Regulator U503 Is 16.8MHz Signal at U200 Pin 19? Check Y201 and associated parts Are signals at Pins 14 & 15 of U200? Check R228 Check R201Is U200 pin 2 >4.5 VDC in Tx &
3-8TROUBLESHOOTING CHARTS 4.0 Troubleshooting Flow Chart for VCO Are Q200 Base at 2.4V Collector at 4.5V Emitter at 1.7VAre U201 Pins 13 at 4.4V 15 at 1.1V 10 at 4.5V 16 at 1.9V Low or no RF Signal at TP1 Visual check of board OK? 35mV DC at U201 Pin 19 NO YES at base of Q200 NO NO NO NO YES YES YES YESLow or no RF Signal at input to PA3.3V DC at U201 Pin 14 & 18 OK? 4.8V DC at U201 Pin 19 Is RF available at C2060 YES YESYESYES YES NO NO NO NO NO Audio =180mVrms at “+” side of D205 2.5VDC at D205 If R211 is Ok, replace D205 Replace R211 Replace R212 NONO YES YES TX VCO RX VCO Correct ProblemVisual check of board OK? Make sure U508 is working correctly and runner between U508 Pin 1 and U201 Pin 14 & 18 is OK Check runner between U200 Pin 2 and U201 Pin 19 Is RF available If all parts from U200 Pin 8 to Base of Q200 are OK, replace U200Check parts between TP1 and Q200 Power OK but no modulation Check Transmiter Pre Driver If all parts associated with the pins are OK, replace U201 4.5V DC at U201 Pin 3 OK? YES NO4.5V DC at U201 Pin 3 OK? YES NO Make sure Synthesizer is working correctly and runner between U200 Pin 28 and U201 Pin 3 is OK 3.3 DC at U201 Pin 14 & 18 OK? OK? OK? If all parts associated with the pins are OK replace U201 If L216, C2071, C2070, C2060 are okay replace U201Check 9V at R230 YES
Troubleshooting Flow Chart for DC Supply (1 of 2) 3-9 5.0 Troubleshooting Flow Chart for DC Supply (1 of 2) Since the failure of a critical voltage supply might cause the radio to automatically power down, supply voltages should first be probed with a multimeter. If all the board voltages are absent, then the voltage test point should be retested using a rising-edge-triggered oscilloscope. If the voltage is still absent, then another voltage should be tested using the oscilloscope. If that voltage is present, then the original voltage supply in question is defective and requires investigation of associated circuitry. Check VDC on C5008 V=3.3V ?Check Voltage on C5043NoGo to D3_3VYe s 9v
3-10TROUBLESHOOTING CHARTS 5.1 Troubleshooting Flow Chart for DC Supply (2 of 2) Check VDC on C5007 V=3.3V ?Check Voltage on C5041NoGo to Digital SectionYe s 9v