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Motorola Astro Digital Mobile Radio Xtl5000 Detailled 6881096c74 B Manual
Motorola Astro Digital Mobile Radio Xtl5000 Detailled 6881096c74 B Manual
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6881096C74-BMay 25, 2005 Troubleshooting Charts: Flowcharts5-31 5.6.17 RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 2 Figure 5-21. RX IF—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 2 Level is -3dB referenced to C5403?No No Ye s Measure the IF signal level (109.65MHz) at C5403 Measure the IF signal level at U5400-3 Check Y5401 No Ye s U5400-4 > 3V and U5400-5 < 0.2V (Without pre-amp) U5400-4 < 0.2V and U5400-5 > 3V (With pre-amp)? Same as level at U5400-3 (Without pre-amp) or -10 dB referenced to level at U5400-3 (With pre-amp)? Ye s Refer to troubleshooting flow digram for Receiver Back EndMeasure the DC voltage level at U5400-4 and U5400-5 Replace U5400Troubleshoot Q5402 and associated circuitry 1
May 25, 20056881096C74-B 5-32Troubleshooting Charts: Flowcharts 5.6.18 RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)— Part 1 of 3 Figure 5-22. RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 1 of 3 Is the IF level at R5034 ~+20dB relative to the RF input?No No No NoNo No Ye s Ye sYe s Ye s Ye s Signal present?Voltage level of >~4.3V at Q5002 Collector? Voltage level of ~1.7V at Q5002 Base (pin 1)? Measure Second LO at C5058, top side towards Abacus III (U5002) pinRefer back to Receiver IF troubleshooting flowchart Measure Abacus 0-3V Digital SSI lines FS,DOUTA, and CLKOUT 3231 Are the levels 0-3V? No Ye s Ye s Frequency CLKOUT at 1.2MHz? No 3 No FS = 20kHz sync pulse? Frequency is 107.4 or 111.9 MHz?Inspect biasing components and solder. Replace Q5002 as necessary Ye s Visually inspect the Second LO VCO Ye sNo Visual examination OK?Make repairs as necessary No problem found DOUTA= 24 bit I, 24 bit Q, 8 bit AGC word (similar to fig X-X, troubleshooting waveforms)? Ye s Go on to RX audio troubleshooting flowchartCheck Voltage Regulator U0505 for normal operation, look for base to emitter drop of ~0.7V on Q5001, replace if necessary
6881096C74-BMay 25, 2005 Troubleshooting Charts: Flowcharts5-33 5.6.19 RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)— Part 2 of 3 Figure 5-23. RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 2 of 3 No 33 1 R5013 = 5.0V? No Ye sYe s R5013 = 0.0V? No Ye s Freq 2nd LO VCO
May 25, 20056881096C74-B 5-34Troubleshooting Charts: Flowcharts 5.6.20 RX Back-End — Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)— Part 3 of 3 Figure 5-24. RX Back-End—Poor SINAD or No Audio (380–470 MHz and 450–520 MHz)—Part 3 of 3 No 3 3 32 DC voltage at R5022 = 0.0V? Ye s No Ye s Freq of CLKOUT
6881096C74-BMay 25, 2005 Troubleshooting Charts: Flowcharts5-35 5.6.21 Low or No RX Injection Signal (380–470 MHz and 450–520 MHz) Figure 5-25. Low or No RX Injection Signal (380–470 MHz and 450–520 MHz) Approx. 5V on C5318?START Low or No RX Injection Signal No No Ye sNo Ye s Ye s Approx. 4.5V on pin 14 of U5303?5 V on C5335? Check RF path from RX VCOCheck R5324, R5325, R5326 Check Voltage Regulator U5301 Check L5299
May 25, 20056881096C74-B 5-36Troubleshooting Charts: Flowcharts 5.6.22 Low or No TX Injection Signal (380–470 MHz and 450–520 MHz) Figure 5-26. Low or No TX Injection Signal (380–470 MHz and 450–520 MHz) Approx. 3.4 V on Q5828-C?START Low or No TX Injection Signal No Ye s Check RF path from TX VCOApprox. 6.5 V on Q5501-C?No Ye sCheck Q5501 and DC Bias Circuitry; replace if necessary Approx. 3.7 V on Q5829-C?No Ye sCheck Q5829 and DC Bias Circuitry; replace if necessary Check Q5828 and DC Bias Circuitry; replace if necessary
6881096C74-BMay 25, 2005 Troubleshooting Charts: Flowcharts5-37 5.6.23 No TX Audio (380–470 MHz and 450–520 MHz) Figure 5-27. No TX Audio (380–470 MHz and 450–520 MHz) 1.0Vpp at R5755 or TP5792?No Ye s 0.4Vpp at C5780?No Ye sCheck deviation tuning or replace U5752 GOTO Controller Section Check synthesizer loop filter componentsNOTE: After the modulated signal is coupled through C5780 the signal is attenuated to levels below 2mv making a measurement difficult for most oscilloscopes. Inject a 2.0Vpp 1kHz tone into Mic input and key radioSTART No TX Audio This Flow chart only checks the modulation path of the FGU. Readings are typical and can vary with deviation settings that are programmed during tuning.
May 25, 20056881096C74-B 5-38Troubleshooting Charts: Flowcharts 5.6.24 TX or RX VCO Unlock (Fail 001) (380–470 MHz and 450–520MHz)—Part 1 of 2 Figure 5-28. TX or RX VCO Unlock (Fail 001) (380–470 MHz and 450–520 MHz)—Part 1 of 2 Frequency Detected? Sniff Frequency near TX or RX VCO or infection stringTX or RX VCO Unlock (Fail 001) No Ye s Check VCO Control Voltage at TP57968.2VDC at Collector of only one of Q5706, Q5707, Q5708, or Q5709 Q5710?No Ye s 3.0VDC on pins 5, 36, and 13 of U5752?Check 9.3 Volt supply path from regulator U0950 in Controller section 11.5VDC or drifting?NoNo Ye sCheck if VCO is locked using spectrum analyzer 13.5VDC at Charge Pump Capacitor C5788?No Ye sCheck Voltage Multiplier Circuitry Go to Controller troubleshooting charts Go to Transmitter or receiver Injection string troubleshooting chartsPlace an Inductive field probe connected to a spectrum analyzer near area to be sniffed. Locked? Ye s 3VDC at pin 4 of U5752?NoNo Ye sCheck for short on pin 4 to controller or replace U5752 Go to Transmitter or receiver Injection string troubleshooting charts A
6881096C74-BMay 25, 2005 Troubleshooting Charts: Flowcharts5-39 5.6.25 TX or RX VCO Unlock (Fail 001) (380–470 MHz and 450–520 MHz)—Part 2 of 2 Figure 5-29. TX or RX VCO Unlock (Fail 001) (380–470 MHz and 450–520 MHz)—Part 2 of 2 Check 3 Volt supply path from Regulator U5750 Check 3 Volt supply pathCheck 3 Volt supply path Refer to Chart to determine which AUX output determines active VCO. 3VDC at pin 5 of U5750?NoCheck 5 Volt supply path from regulator U0505 Unlock RX or TX?TX RX Ye s Required Aux pins at 3.0VDC for RX?No No Ye sCheck U5752 Check U5753, Q5708, Q5709, and Q5710Ye sRequired Aux pins at 3.0VDC for TX?No No Ye sCheck U5752 Check U5753, Q5706, and Q57073.0VDC at E6750? 3.0VDC at E6750?Ye s A
May 25, 20056881096C74-B 5-40Troubleshooting Charts: Flowcharts 5.6.26 RF Power Amplifier (RFPA)—No or Low TX Power Output (380–470 MHz and 450–520 MHz)—Part 1 of 5 NOTE:For each flowchart step in which reference is made to a note, be sure to refer to that specific note (located on page 61 of this flowchart) for guidance in performing the actual troubleshooting procedure. Also, RFPA DC voltages are shown in Table 5-6 on page 5-44. Figure 5-30. RF Power Amplifier (RFPA)—No or Low TX Power Output (380–470 MHz and 450–520 MHz)— Part 1 of 5 Read General Notes before proceeding. Read specific notes as indicated Check battery cable, mic, and control head connections START Continuous red light while mic button is depressed?GOTO Sythesizer- No Transmit Chart Tune power with Tuner? (see help text) No Yes Tune current limit with Tuner (see help text) Yes No TX injection power less than 0.5 mW? (Note 1)GOTO Sythesizer- No or Low Tx Injection Chart Yes K9.1V present at Q0952, pin 1 in power control section when transmitter is keyed? No GOTO Power Control - No K9.1V Chart for 700-800 MHz RFPA_CNTRL voltage (TP5503) less than 4.8 V when transmitter is keyed? YesNo GOTO Power Control - No or low RFPA_CNTRLChart for 700-800 MHz No U5501 drain biases voltages per Table 1? (Note 3) Yes No Check/repair/ replace defective parts Yes No A Is U5501, VCNTRL resistance < 1 kOhms? (Note 2)YesRepair/replace U5501 No Is U5501, RFOUT and VD1 resistance < 1 MOhms? (Note 4)Yes Repair/replace U5501