Motorola Cp200 Detailed 6880309n62 C Manual
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6880309N62-CJune, 2005 146-174 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry 5-7 C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. Figure 5-5. VHF VCO Block Diagram Presc RX TX Matching Network Pin 8 Pin 14 Pin 103V (U330 Pin 5) VCC BuffersU201 Pin 32 AUX3 (U201 Pin 2) Prescaler Out Pin 12 Pin 19 Pin 20 TX/RX/BS Switching Network U251 VCOBIC Rx Active Bias Tx Active Bias Pin 2 Rx-I...
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June, 20056880309N62-C 5-8146-174 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry Notes:
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Chapter 6 VHF Troubleshooting Tables 6.1 Troubleshooting Table for Receiver Table 6-1. Troubleshooting Table for Receiver Symptom Possible Causes Procedure Corrective Action Radio Dead (no turn-on beep, no LED indication)1. Battery dead or defec- tive.Substitute known good battery or battery eliminator.Charge or replace battery. 2. Defective battery con- tacts.Inspect battery contacts for corrosion or bent terminals.Clean/repair/replace J301. 3. Blown fuseCheck voltage on each side of fuse. If...
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June, 20056880309N62-C 6-2VHF Troubleshooting Tables: Troubleshooting Table for Receiver No Audio 1. Synthesizer out of lockVerify U201-4 is at 3 V dc.Troubleshoot synthesizer/VCO circuits. 2. Defective IFIC Verify audio is present at U51-8. Check Q70, Y70, U51. 3. RX audio buffer faultVerify audio is present at U451-2.Check U510 and associated parts. 4. ASFIC fault Verify audio is present at U451-41. Verify U451-14 is high.Check squelch setting, PL/DPL programming. Troubleshoot/ replace U451. 5....
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6880309N62-CJune, 2005 VHF Troubleshooting Tables: Troubleshooting Table for Synthesizer 6-3 6.2 Troubleshooting Table for Synthesizer Table 6-2. Troubleshooting Table for Synthesizer Symptom Possible Causes Procedure Corrective Action Synthesizer Out of Lock (RX mode only)1. VCO faultVerify oscillator is working, check RF level at U251-10 per schematic. Check dc voltages at U251 pin 2 through 6 and 10 per Table 6-4. Verify steering line voltage is between ~3 V and 10 V. Check VCO tank components...
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June, 20056880309N62-C 6-4VHF Troubleshooting Tables: Troubleshooting Table for Transmitter 6.3 Troubleshooting Table for Transmitter Table 6-3. Troubleshooting Table for Transmitter Symptom Possible Causes Procedure Corrective Action No Transmit (no TX LED indication)1. PTT switch defective.Verify U401-71 goes low when PTT is pressed.Replace PTT switch S441. 2. EXT MIC PTT fault Verify U401-72 goes low when J471- 4 is grounded.Check/replace Q470, L471 etc. No Transmit (TX LED indication OK) 1....
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6880309N62-CJune, 2005 VHF Troubleshooting Tables: Troubleshooting Table for Transmitter 6-5 Low Power 1. Low TX injectionCheck that RF level at jct. R100/ R101 per schematic.Check U251, L291-292, C290- 291. 2. Low gain in TX stage Verify dc voltage at Q100-E is ~1.3 V (VHF) or ~0.5 V (UHF). Verify that RF level at U110-1 is approx. 1 V (VHF) or 1.6 V (UHF).Verify 5T voltage is correct. Troubleshoot Q100 circuitry. Troubleshoot Q100 circuitry. Check/replace Q100. 3. Incorrect control volt- ageVerify...
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June, 20056880309N62-C 6-6VHF Troubleshooting Tables: Troubleshooting Table for Transmitter No EXT MIC audio 1. Mic bias fault Verify approx 1.8 V dc across EXT MIC cartridge in TX mode. Verify audio present (~10 mV rms) when speaking into mic.Check Q470. R475, R477, L471. Check VR473, VR475, D470 for shorts. 2. Audio path faultVerify mic audio present (~10 mV rms) at U451-46. Verify amplified mic audio present (~200 mV rms) at U451-40.Check L471, C470. Check/replace U451. 3. Defective audio...
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6880309N62-CJune, 2005 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 6-7 6.4 Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals IC Designator Pin Pin Function DC Voltage Comments (Condition) U51 IFIC1RF input 44.85 MHz1.20 2 RF input decoupling 1.20 32nd LO osc output4.02 4 2nd LO osc input 4.60 5RSSI output0.74(no received signal) 6 Vcc 4.70 7Audio feedback0.89 8 Audio output 1.44 DEMOD to stage U510 9RSSI...
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June, 20056880309N62-C 6-8VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals U110 RF Power Amp 1RF input0(TX mode) 2 Vgg (gate bias) 2.65 (typ) (TX mode) (4.25 V typ at VHF) 3Vdd 6.59(TX mode) 4 RF output -- Do not measure 5GroundGND U150 Dual Opamp1 Unit 1 output 4.20 (typ) (TX mode) (5.8 V typ at VHF) 2Unit 1 (-) input2.39 (typ)(TX mode) 3 Unit 1 (+) input 2.39 (typ) (TX mode) 4GroundGND 5 Unit 2 (+) input 3.30 (typ) (TX mode) 6Unit 2 (-) input3.35 (typ)(TX mode) 7 Unit 2 output...