background image

MAINTENANCE

LBI-38425A

5

3 MAINTENANCE

3.1 PREVENTIVE 

MAINTENANCE

To insure high operating efficiency and to prevent mechanical and electrical failures
from interrupting system operations, routine checks should be made of all mechanical
and electrical parts at regular intervals.  Preventive maintenance should include the
following checks:

3.1.1 Connections

Ground connections to the voltage source should be periodically checked for tightness,
Loose or poor connections to the power source will cause excessive voltage drops and
faulty operation. 

 

When ground connections are not made directly to the battery, the

connection from the battery to vehicle chassis must be checked for low impedance.  A
high impedance may cause excessive voltage drops and alternator noise problems.

3.1.2 Electrical 

System

Check the voltage regulator and alternator or generator periodically to keep the electrical
system within 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 operation.  A weak battery will often cause
excessive noise or faulty operation.

3.1.3 Mechanical 

Inspection

Since mobile units are subject to constant shock and vibration, check for loose plugs,
nuts, screws and parts to make sure that nothing is working loose.

3.1.4 Antenna

The antenna, antenna base, and all contacts should be kept clean and free from dirt or
corrosion.  If the antenna or its base should become coated or poorly grounded, loss of
radiation and a weak signal will result.

3.1.5 Alignment

The transmitter and receiver meter readings should be checked periodically, and the
alignment “touched up” when necessary.  Refer to applicable Alignment Procedure and
Troubleshooting sheet for typical voltage readings.

3.1.6 Frequency 

Check

Check transmitter frequency and deviation.  Normally, these checks are made when the
unit is first put into operation, after the first six months and once a year thereafter.

Содержание MLS II MLSH041

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

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

Страница 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...

Отзывы: