Shure_LX4_Wireless_Receiver_Service_Manual 电路图.pdf

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1、Shure Brothers Incorporated 222 Hartrey Avenue Evanston IL 60202-3696 U.S.A. LX Wireless System ?1999, Shure Incorporated Printed in U.S.A. 2510081 (BK) SERVICE MANUAL CHANGE NOTICE LX4 DIVERSITY RECEIVER Changes and corrections have been made to the Service Manual for the LX4 Diversity Receiver. To

2、 update your Service Manual, remove the pages identified in the tables below and replace them with the pages at- tached to this Change Notice. Note that there are no changes to pages not specifically identified in the tables below. LX4 DIVERSITY RECEIVER SERVICE MANUAL REVISION HISTORY ReleasePart N

3、umberDate CodeColor Original25A1008QHWhite Revision 125B1008QLPink Revision 225C1008SCTan Revision 325D1008SIWhite Revision 425D1008TLWhite Revision 525D1008BKWhite CHANGES EFFECTIVE NOVEMBER 18, 2002 REMOVE these pages from the LX4 Service Manual INSERT these pages into the LX4 Service Manual Pages

4、 14 or 220 to 240 Vac, 50/60 Hz for export models. The dc power connector: is a male pin coaxial jack with locking connector. A green power LED, D11, indicates when power is being supplied to the receiver by an external power converter. The circuitry will operate normally with an input of 12.5 to 18

5、 Vdc. Reverse polarity protection is provided by D8, and voltage regulation is accomplished by U7. The power input, HI-Z and balanced LO-Z output connectors are filtered to prevent local oscillator radiation from the cables and to protect the receiver from the effects of external electromagnetic fie

6、lds. Shure LX4 Diversity Receiver 6Test Component Locations 25D1008 (BK) Test Component Locations Shure LX4 Diversity Receiver Preliminary Tests725D1008 (BK) Preliminary Tests Listening Test Before completely disassembling the receiver, operate it to determine whether it is functioning normally and

7、try duplicating the reported malfunction. Refer to the User Guide for operating instructions, troubleshooting sugges- tions, and specifications. Review any customer complaint or request, and focus the listening test on any reported problem. The following, more extensive, functional tests require par

8、tial disassembly. Functional Tests Refer to the Disassembly section to partially disassemble the receiver for the following functional tests. Use dc blocks at all rf output to protect test equipment. Verify operation and reported malfunction, referring to the product Users Guide for a description of

9、 the unit as well as information on its operation, troubleshooting, and technical data. Shure LX4 Diversity Receiver 8Preliminary Tests 25D1008 (BK) Rf Test Receivers that pass this test do not contain any “drop-out” or “range” problems. RF SIGNAL GENERATOR NOTE: DC VOLTAGES ARE PRESENT AT MOST RF T

10、EST POINTS. USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT. 12.5 18.9 VDC POWER RF ARF BAUDIO SQUELCH LEVEL ANTANT OUTPUTS HI Z BAL MICLINE POWER AB MARCAD DIVERSITY DC BLOCK LX4 ReceiverRf Signal Generator Power:ONFrequency:Receiver frequency Level (gain):MaxModulation:None Squ

11、elch:Mid Figure 2.Rf Alignment Functional Test Set-Up For channel A: 1.Set the receivers squelch control to its middle position and the volume control to its maximum position. 2.Set the rf generator to the receivers frequency. 3.Remove the receivers antenna. Plug the BNC end of the 50 test cable int

12、o the signal generator and the other end to the channel A antenna input. 4.Apply power to the LX4. 5.Verify that the unit unsquelches with rf signals greater than 89 dBm. 6.When the unit unsquelches, verify that the “Rf” LED glows. Repeat this test for channel B. Shure LX4 Diversity Receiver Prelimi

13、nary Tests925D1008 (BK) Audio Tests RF SIGNAL GENERATOR NOTE: DC VOLTAGES ARE PRESENT AT MOST RF TEST POINTS. USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT. AUDIO ANALYZER 12.5 18.9 VDC ANTANT OUTPUTS HI Z BAL MICLINE POWER AB DC BLOCK LX4 ReceiverAudio AnalyzerRf Signal Genera

14、tor Power:ONOutput amplitude:Set to turn OFF high and low EXT lights on rf signal generator Level: 60 dBm Level (gain):MaxFilters:Deviation:15 kHz Squelch:Mid400 Hz High-Pass:ONModulation:EXT 1 kHz 30 kHz Low-Pass:ONFrequency:receiver frequency Figure 3.Audio Test Set-Up, steps 1 5 Note: The amplitu

15、de may have to be adjusted so that neither the HI EXT nor the LO EXT LEDs on the rf signal generator are on. This amplitude should be between 1.4 and 1.5 V rms. 1.Set the rf signal generator level to 60 dBm, its deviation to 15 kHz, and its external modulation to 1 kHz. 2.Adjust the audio analyzers

16、output amplitude so that the high and low EXT lights on the rf signal generator are off. 3.Using a 3.3 k load, connect the receivers unbalanced audio output to the audio analyzer. The receivers volume control should still be in its maximum position. 4.Engage the 400 Hz high-pass filter and the 30 kH

17、z low-pass filter on the audio analyzer. 5.Verify the following receiver measurements: ?Audio level is 400 mVrms, ?90 mV. Record the measurement as a reference level for the following steps. ?total harmonic distortion (THD) is 0.75%. Shure LX4 Diversity Receiver 10Preliminary Tests 25D1008 (BK) RF S

18、IGNAL GENERATOR NOTE: DC VOLTAGES ARE PRESENT AT MOST RF TEST POINTS. USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT. AUDIO ANALYZER 12.5 18.9 VDC ANTANT OUTPUTS HI Z BAL MICLINE POWER AB DC BLOCK LX4 ReceiverAudio AnalyzerRf Signal Generator Power:ONOutput amplitude:Set to turn

19、 OFF high and low EXT lights on rf signal generator Level: 60 dBm Gain:MaxFilters:Deviation:15 kHz Squelch:Mid400 Hz High-Pass:OFFModulation:EXT 1 kHz 30 kHz Low-Pass:ONFrequency:Receiver frequency Figure 4.Audio Functional Test Set-Up, steps 6 14 6.Use external modulation only on the rf signal gene

20、rator. Input a 100 Hz signal from the audio analyzer to the external modulation input of the rf signal generator. 7.Disengage the 400 Hz highpass filter on the audio analyzer. 8.Verify that the receivers unbalanced audio output is within +2 dB, 1 dB of the reference level recorded in step 5. 9.Chang

21、e the audio analyzers frequency to 10 kHz. 10. Verify that the receivers unbalanced audio output is 7.5 dB to 10.5 dB from the reference level recorded in step 5. 11. Place a 150 load across the receivers balanced output. Verify that it is in the MIC position. 12. Connect this output to the audio an

22、alyzer and select the float position. Verify that the output is 65 mVrms, ?15 mV. 13. Remove the 150 load. 14. Take the audio analyzer input out of the float position. Repeat this test for channel B. After all testing has been completed, remove the test cable and reinstall the antenna. If the receiv

23、er passes these tests, the unit is functioning correctly and does not require alignment. Shure LX4 Diversity Receiver Disassembly and Assembly1125D1008 (BK) Disassembly and Assembly ! IMPORTANT SAFETY INSTRUCTIONS ! 1.READ these instructions. 2.KEEP these instructions. 3.HEED all warnings. 4.FOLLOW

24、all instructions. 5.DO NOT use this apparatus near water. 6.CLEAN ONLY with a damp cloth. 7.DO NOT block any of the ventilation openings. Install in accordance with the manufacturers instructions. 8.DO NOT defeat the safety purpose of the ground- ing-type plug. The third prong is provided for your s

25、afety. When the provided plug does not fit into your outlet, consult an electrician for replacement of the obsolete outlet. 9.PROTECT the power cord from being walked on or pinched, particularly at plugs, convenience receptacles, and the point of exit from the apparatus. 10.USE only attachments/acce

26、ssories specified by the manufacturer. 11.USE only with a cart, stand, tripod, bracket, or table specified by the manufacturer or sold with the apparatus. When a cart is used, use caution when moving the cart-apparatus combination to avoid injury from tip-over. 12.UNPLUG this apparatus during lightn

27、ing storms or when unused for long periods of time. 13.REFER all servicing to qualified service person- nel. Servicing is required when the apparatus has been damaged in any way, such as when the power-supply cord or plug has been damaged, liquid has been spilled or objects have fallen into the appa

28、ratus, the apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped. ! CAUTION ! Observe precautions when handling this static-sensitive device. ! WARNING ! Voltages in this equipment are hazardous to life. No user-serviceable parts are inside. Refer all servici

29、ng to qualified service personnel. The safety certifications of the LX4 Diversity Receiver do not apply when the operating voltage is changed from the factory setting. Disassembly Remove the case: 1.Remove the six screws from the case top, which includes two screws on the top and two screws on eithe

30、r side. 2.Slide the case off the frame from front to back. The front panel must be removed to access the printed circuit board: 3.Remove the clip from the center front panel frame screw tabs. 4.Unlock the four snap-in tabs to detach the front panel. Begin with the bottom two tabs, placing your finge

31、rs on the bottom of the chassis just behind each tab and squeezing down with your thumbs on the top of the front panel. 5.Next, release the two top tabs. Shure LX4 Diversity Receiver 12Disassembly and Assembly 25D1008 (BK) Remove the printed circuit board (pcb): 1.Remove the nuts and washers from th

32、e antenna input connectors and the HI-Z audio output connector. 2.Remove the two screws on either side of the balanced output XLR connector. 3.Unplug the dc power input from the pcb. 4.Remove the six screws anchoring the pcb to the bottom of the chassis. 5.Lift the pcb from the front and pull forwar

33、d. Note the lock washers on the inside of the antenna connectors and HI-Z audio output connector. Reassembly Replace the printed circuit board: 1.Carefully replace the six screws that anchor the pcb to the bottom of the chassis and replug the dc power input to the pcb. Note the lock washers on the i

34、nside of the antenna connectors and HI-Z audio output connector. 2.Replace the two screws on either side of the balanced output XLR connector. 3.Replace the nuts and washers from the antenna input connectors and the HI-Z audio output connector. Replace the front panel: 1.Slide the case on the frame

35、from front to back. 2.Lock the four snap-in tabs to attach the front panel. 3.Replace the six screws from the case top (two screws on the top and two screws on each side). 4.Replace the clip from the center front panel frame screw tabs. Shure LX4 Diversity Receiver Service Procedures1325D1008 (BK) S

36、ervice Procedures Test Equipment Most test equipment needed is described in the Shure Wireless Service Equipment Manual. The following test equipment (or approved equivalent) is also needed. Table 1 Test Equipment Equipment TypeModel Audio analyzer*Hewlett-Packard 8903B Digital multimeterFluke 87 Rf

37、 signal generatorHewlett-Packard 8656B Frequency counterHewlett-Packard 53181A Spectrum analyzerHewlett-Packard 8590L *Audio levels in dBu are marked as dBm on the HP8903B. Changing the Frequency System Operating Frequencies The LX4 Diversity Receiver printed circuit board is marked with a group let

38、ter that identifies the range of frequencies the receiver can operate within. The operating frequency may be changed to a different frequency within the same group. Before changing the operating frequency, refer to the Functional Test section and check the receiver for proper opera- tion. Change the

39、 frequency by changing the crystal on the rf board. For proper operation, the crystal must be obtained from Shure and must operate within the frequency range of the pc board. Use the following equation to determine the operating frequency: Carrier frequency = 3 x (nominal crystal frequency in MHz) +

40、 10.71 MHz After the new crystal is installed, operational tests and alignment pro- cedures must be performed to ensure that the receiver is operating cor- rectly. The pcb label should also be updated to show the new frequency and letter identification code. Shure LX4 Diversity Receiver 14Service Pr

41、ocedures 25D1008 (BK) Table 2 Wireless Frequency Selections CodeFrequencyPrinted Circuit Board Assembly 169.445 169.505 170.000 170.245 A 170.305 A 171.045 171.105 171.845 171.905 173.800 174.100 174.400 174.500 175.000 B 176.200 B 176.600 177.000 177.600 180.400 182.000 182.200 C 183.200 C 183.600

42、184.600 186.200 186.350 D 186.600 D 189.000 190.600 191.900 T90_8632 192.200 T90_8632 192.600 E 195.000 E 196.600 197.600 198.600 200.300 200.350 F 201.650 F 202.200 203.000 204.200 204.600 206.000 G 208.200 G 208.300 209.000 H 216.100 216.300 217.000 218.200 J 218.600 J 219.600 221.350 232.825 L 23

43、3.125 L 234.625 237.325 Shure LX4 Diversity Receiver Service Procedures1525D1008 (BK) Alignment The following steps are for channel A; channel B, is in parentheses. For example, TPA7 (TPB7) means to use TPA7 for channel A and TPB7 for channel B. RF SIGNAL GENERATOR NOTE: DC VOLTAGES ARE PRESENT AT M

44、OST RF TEST POINTS. USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT. TP9 TPA4 12.5 18.9 VDC ANTANT OUTPUTS HI Z BAL MICLINE POWER AB TPB4 J2 DC BLOCK LX4 ReceiverRf Signal Generator Power:ONFrequency:carrier Gain:MaxModulation:OFF Squelch:MidAmplitude:60 dBm Figure 3.Alignment Te

45、st Setup 1.Solder a 33 k resistor between TPA4 (TPB4) and ground for rf adjustments. Do the same for channel B with TPB4. 2.Set the rf signal generator frequency to the same as the LX4, with no modulation, and its amplitude at 60 dBm. 3.Connect the power supply (PS40) to 120 Vac power and to the rec

46、eivers dc input connector (J2). The green power on LED of the LX4 should now be illuminated. If not, there is a circuit mal- function. 4.Connect the rf signal generator to the 50 antenna input for channel A or channel B, as appropriate. 5.Verify that 10.0 0.35 Vdc is present at TP9 (U7, pin 3), usin

47、g a digital multimeter (DMM). Preset the adjustable circuit components as follows: 6.Set volume (R32) control fully clockwise. 7.Set squelch (R66) control to midrange. 8.Turn the LX4 power OFF. Shure LX4 Diversity Receiver 16Service Procedures 25D1008 (BK) Received Signal Strength Indicator (RSSI) A

48、djustment RF SIGNAL GENERATOR NOTE: DC VOLTAGES ARE PRESENT AT MOST RF TEST POINTS. USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT. TPA4 12.5 18.9 VDC POWER RF ARF BAUDIO SQUELCH LEVEL ANTANT OUTPUTS HI Z BAL MICLINE POWER AB MARCAD DIVERSITY TPB4 TPA7 TPB7 L100 L101 L103 L104 L

49、105 L114 L108 L113 L112 L111 L208 L205 L204 L203 L200 L201 DC BLOCK LX4 ReceiverRf Signal Generator Power:OFFFrequency:carrier Gain:MaxModulation:off Squelch:MidMod source:none Deviation:none Amplitude:off Figure 4.RSSI Test Setup 1.Verify that the LX4 power is OFF. 2.Place a jumper between TPB7 and ground to mute channel B for channel A alignment. (Place a jumper between TPA7 and ground to mute channel A for channel B alignment.) 3.Turn the LX4 power ON. 4.