Comnet MLS II MLSH041 Maintenance Manual Download Page 22 | Manualshive

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LBI-38425A

ALIGNMENT AND TROUBLESHOOTING PROCEDURES

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Summary of Contents for MLS II MLSH041

Page 1: ...LBI 38425A Maintenance Manual Service Section MLS II Highband Two Way Mobile Radios MLSH041...

Page 2: ...the United States This manual is published by Com Net Ericsson Critical Radio Systems Inc without any warranty Improvements and changes to this manual necessitated by typographical errors inaccuracies...

Page 3: ...mbly Procedure 9 4 1 To Remove the System Control Synthesizer Board 9 4 2 To Remove the Transmitter Receiver Board 9 4 3 To Remove the Front Panel Control Unit 10 5 Alignment and Troubleshooting Proce...

Page 4: ...ANSMITTER ADJUSTMENT The transmitter has been adjusted at the factory and should require no readjustment However the antenna length should he adjusted for optimum VSWR and the frequency and modulation...

Page 5: ...hin safe and economical operating limits Over voltage is indicated when the battery loses water rapidly Usage of 1 or 2 ounces of water per cell per week is acceptable for batteries in continuous oper...

Page 6: ...ly 3 Gently lift up on the module taking care not to damage the spacer under the module SERVICE NOTE The module may stick to the printed board 3 2 2 To Replace Driver HC1 1 Position the module properl...

Page 7: ...uired to the lead length of the removed transistor 5 Apply silicon grease to the back of the replacement transistor and place the transistor into the mounting slot 6 Replace the transistor mounting sc...

Page 8: ...tinned end of the component on the tinned pad on the board and simultaneously touch the component and the pad with a well tinned soldering iron while pressing the component down on the board 3 Place...

Page 9: ...the top cover refer to Figure 3 Remove the top cover Then disconnect the interconnecting cables 2 Remove the eight 8 screws securing the Synthesizer shield Remove the shield 3 Remove the three 3 scre...

Page 10: ...e stopper and remove the power supply cable 5 Remove the two 2 screws securing power module HC1 Remove the screws securing the power transistor TR1 6 Remove the two 2 screws securing the board Careful...

Page 11: ...DISASSEMBLY PROCEDURE LBI 38425A 11 Figure 4 Disassembly Procedure Bottom View Figure 5 Disassembly Procedure Front Panel...

Page 12: ...roblems that might arise in the System Control Synthesizer Board the Transmitter and the Receiver 5 1 SYNTHESIZER The Alignment and Troubleshooting procedures for Synthesizer Circuitry on System Contr...

Page 13: ...est transmit frequency is 156 8 MHz Select highest frequency transmit channel With 50 ohm load on the antenna connector J1 key the radio Monitor TP201 with a digital voltmeter and tune CV202 for 7 0 V...

Page 14: ...is first keyed If delayed the rapidly rising ambient temperature must be taken into consideration The Oscillator frequency should be set at 25 C ambient temperature 1 J201 or J1 FREQ TRIM Control on T...

Page 15: ...ne to J602 2 and with the radio keyed vary its amplitude until the Deviation Monitor reads 2 kHz Note the level 5 Change the audio oscillator frequency for a 10 Hz tone at the same level and set LOOP...

Page 16: ...1 kHz modulation Set the RF signal level to 1000 microvolts Move P551 from J551 1 2 to J551 2 3 on the Transmitter Receiver Board Connect RF signal generator to J1 Terminate J701 1 6 with a 4 ohm 6 wa...

Page 17: ...38425A 17 NO OPERATION DC VOLTAGE IC701 38 5V CHECK IC609 IC701 4 HIGH 5 1 8 Control Logic Troubleshooting RC 5432B CHECK IC608 REPLACE X701 CHECK IC704 IC708 CHECK IC701 IC702 IC703 PSEN IC701 26 RUN...

Page 18: ...prepared for adjustments and confirmations of the Exciter PA section and covers the following items 5 2 2 Measuring Instruments AVR DC Power Supply DC 0 20V 20A Power Meter usable at the value above 8...

Page 19: ...MENT AND TROUBLESHOOTING PROCEDURES LBI 38425A 19 ADJUSTMENT SYSTEM AVR POWER SUPPLY RADIO DIRECTIONAL COUPLER POWER METER SPECTRUM ANALYZER ATT SPECTRUM ANALYZER 30 dB FOR MEASURING SPURIOUS ONLY RC...

Page 20: ...of TR6 collector is 9V at TP4 and that the relay K1 clicks at this time 3 Setting APC off power RV1 RV2 Connect RF cable P101 to J201 Turn the volume RV1 on APC fully clockwise CW Next turn the volum...

Page 21: ...ALIGNMENT AND TROUBLESHOOTING PROCEDURES LBI 38425A 21 TRANSMITTER TROUBLESHOOTING...

Page 22: ...LBI 38425A ALIGNMENT AND TROUBLESHOOTING PROCEDURES 22...

Page 23: ...150 8 174 MHz DC Voltmeter Frequency Counter up to 500 MHz with 0 05 V sensitivity Audio Level Meter and Distortion Analyzer 4 Ohm 6 Watt Resistor 5 3 1 1 Preliminary Adjustment 1 Connect 13 8 VDC to...

Page 24: ...al level to 1000 microvolts Connect the audio level meter use a high impedance meter to TP503 Adjust the L513 until audio output level becomes maximum 4 J701 1 6 See Procedure Move P551 from J551 1 2...

Page 25: ...r poor sensitivity distortion or low gain By following the sequence of test steps starting with Step 1 the defect can be quickly localized Once the defective stage is pin pointed refer to the Service...

Page 26: ...circuit Tune the filter for minimum reading or null on the lowest possible scale 100 30 etc 3 Place the RANGE switch to SET LEVEL position filter out of the circuit and adjust the input LEVEL control...

Page 27: ...on the 30 range 3 While increasing the deviation of the Signal Generator switch the RANGE control from SET LEVEL to distortion range until a 12 dB difference is obtained between the SET LEVEL and dis...

Page 28: ...LBI 38425A ALIGNMENT AND TROUBLESHOOTING PROCEDURES 28...

Page 29: ...ALIGNMENT AND TROUBLESHOOTING PROCEDURES LBI 38425A 29 This Page Intentionally Left Blank...

Page 30: ...Com Net Ericsson Critical Radio Systems Inc P O Box 2000 Lynchburg Virginia 24501 Phone 1 800 431 2345 or Outside USA 1 804 592 6100 www com netericsson com Printed in U S A...

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