shure_u1_sm 电路图.pdf

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1、Shure Incorporated 222 Hartrey Avenue Evanston IL 60202-3696 U.S.A. UHF Wireless System ?2000, Shure Incorporated Printed in U.S.A. 2510212 (BG) SERVICE MANUAL CHANGE NOTICE U1/U1L UHF BODY-PACK TRANSMITTER Changes and corrections have been made to the Service Manual for the U1/U1L UHF Body-Pack Tra

2、ns- mitter. These changes will make it easier to repair the transmitters. To update your Service Manual, remove the pages identified in the tables below and replace them with the pages attached to this Change Notice. Note that there are no changes to pages not specifically identified in the tables b

3、elow. U1/U1L SERVICE MANUAL REVISION HISTORY ReleasePart NumberDate Code Original25A1021QE Revision 125B1021SA Revision 225C1021TD Revision 325C1021AG Revision 425C1021BF Revision 525C1021BG CHANGES EFFECTIVE JULY 12, 2002 REMOVE these pages from the U1/U1L Service Manual INSERT these Revised pages

4、into the U1/U1L Service Manual 21 to 25 21 to 25 RadioFans.CN 收音机爱 好者资料库 RadioFans.CN 收音机爱 好者资料库 ?1999, Shure IncorporatedPrinted in U.S.A. 25B1021 (BG) Service Manual U1/U1L Body-Pack UHF Transmitter General Characteristics The Shure U1/U1L Body-Pack UHF Transmitter is a microprocessor- controlled

5、body-pack transmitter operating in the UHF frequency range. This product is intended for use in high-end installed sound, rental, and concert sound applications. Different frequency variations are available. Controls and Indicators 1.Antenna 2.Programmable Display 3.Input Connector (U1L uses LEMO co

6、nnectors) 4.ON/OFF Switch 5.On/Off LED 6.Belt Clip 7.MODE Button 1213 11 10 O N 541 6 9 7 2 O FF 1 3 8 8.SET Button 9.Audio Gain Control 10. Battery Cover Release Tabs 11. Battery Compartment Cover 12. Battery Fuel Gauge 13. Battery Compartment NOTE: All models shipped after February 1999 have a sol

7、dered attached antenna to replace the screw-on removable antenna. . Figure 1.U1/UL Transmitter Controls and Indicators Service Note: Shure recommends that all service procedures be performed by a Factory-Authorized Service Center or that the product be returned directly to Shure Brothers Inc. Licens

8、ing: Operation may require a user license. Frequency or power-output modifications may violate this products approvals. Contact your countrys communications authorities. RadioFans.CN 收音机爱 好者资料库 Shure U1/U1L Body-Pack UHF Transmitter 25C1021 (BG)2Circuit Description Circuit Description Audio Section

9、Audio enters L201, an inductor that is used as an rf choke. The signal enters a 6 dB pad made up of R203, R204, C204, and C206. The signal is ac-coupled through C205 into a 40 dB (30 dB for JB frequencies) user-adjustable gain stage around U201A. This gain stage is externally accessible to the user.

10、 C201, C202, and C207 protect the pre-amplifier and bias circuits from rf interference. R205 and R207 set up a half-supply bias, and R206 sets the ac input impedance. The amplified audio signal is then passed through a pre-emphasis network before entering the compression stage. R208, R211, and C211

11、set up two corners for the pre-emphasis network. The pre-emphasis network boosts the high frequencies before transmission and helps set the hinge point (0 dB gain) of the compandor. The network feeds NE575 compandor U203, which utilizes an external amplifier U202B. The com- pandor performs 2:1 logar

12、ithmic compression of the audio signal. Transistors Q201 and Q202, along with crystal Y202, form the tone key oscillator circuit, which provides a stable, continuous 32.768 kHz sine wave. Transistor Q204 buffers the tone key signal before it is added to the audio signal. The tone key signal is used

13、in the receiver to provide audio output only when the tone key signal is present in the transmitted signal. Therefore, if the tone key or the transmitter is turned off, the receiver will be muted. Q203 acts as a switch for toggling the tone key on and off. It is controlled via the microprocessor. R2

14、24 allows the tone key amplitude level to be set. The tone key circuit is powered by U208B, which is a dc amplifier that multiplies the 3 V battery voltage to 4.5 V (gain = 1.5). As the battery voltage drops, the tone key supply voltage also drops, which decreases oscillator amplitude. The tone key

15、amplitude is used by the receiver to indicate transmitter battery strength. The tone key feature indicates battery level at the receiver. It is not available on JB models. The tone key signal, along with the processed audio signal, is fed to summing amplifier U202A. Resistors R232 and R233 set up a

16、half-supply bias. Resistor R231, located at the output of the summing amplifier, pre- vents spurious oscillations from the operational amplifier. After passing through ac-coupling capacitor C232, the signal is fed to the rf module. Shure U1/U1L Body-Pack UHF Transmitter 325C1021 (BG)Circuit Descript

17、ion Rf Section Processed audio enters R243, an internal potentiometer adjusted for 45 kHz deviation (100% modulation) with a 7.2 dBV, 1 kHz tone, at the output of the front audio stage (pin 1 of U201). On JB models, R243 is adjusted for 5 kHz deviation with 63.2 dBV, 1 kHz tone, at the input to the

18、transmitter. The audio is then fed to the tuning voltage pin of the voltage controlled oscillator (VCO) and modulates the carrier directly. The use of a phase locked-loop (PLL) frequency synthesized system eliminates the need for multiplier stages, resulting in a much higher degree of spectral purit

19、y. The VCO is shielded against interference from external rf fields. Regulated +5 Vdc power from the dc-to-dc converter ensures frequency stability, even if the battery voltage changes. At the output of VCO U205, the rf signal splits into two paths. The output of the VCO is coupled by C244 to the fr

20、equency control pin of synthesizer U204. The synthesizers internal circuitry divides the signal as necessary to reach the desired reference frequency. The synthesizer contains a quartz-controlled reference oscillator circuit, including a 4.0 MHz crystal (Y201), that is adjusted by means of trimmer c

21、apacitor C239. The transmitter output frequency is user-selectable. Frequency selection is made via microprocessor U103, which interfaces with the user by means of the mode/select switches. The output of the synthesiz- er is a series of pulses that are integrated by a passive loop filter (R238, C245

22、, R240, C266, C267, R239, and C247) to produce a control voltage signal. The control voltage signal is then connected to the VCO through amplifier U210A, which is used to isolate the PLL filter from the audio modulation signals. The VCO output is also coupled to an rf power amplifier through a resis

23、tive pad consisting of R254, R255, R256, R257, and an LC match- ing network containing C261, L209, and C248. The rf power amplifier, dual gate MESFET Q208, is fixed-tuned and configured as a common source device. Amplifier stability is obtained through resistive loading on the input, R247. The outpu

24、t of Q208 contains a low-pass matching network (L206) and an LC-type low-pass filter (LP206), which provide a high degree of spectral purity. The output of the low-pass filter feeds a microwave isola- tor that reduces the production of reverse third-order intermodulation products. The transmitter is

25、 capable of delivering a maximum of +10 dBm (10 mW) to the 50 antenna. During transmitter power-up and frequency selection, rf power is muted by bringing the base of Q209 high. This pro- vides approximately 45 dB rf attenuation until the PLL has locked. The transmitter rf is then unmuted by bringing

26、 the base of Q209 low. During transmitter power off conditions, voltage is first removed from the VCO by bringing the base of Q207 high. In this way, the transmitter carrier signal is not allowed to drift off frequency during power on or power off conditions. Shure U1/U1L Body-Pack UHF Transmitter 2

27、5C1021 (BG)4Circuit Description Transmitter Display Board The display board consists of the following circuitry blocks. Microcontroller Section The microcontroller section consists of microcontroller U103 and the liquid crystal display (LCD). The microcontroller has an on-board liquid crystal displa

28、y (LCD) driver. R111, R113, and R114 supply the microcon- troller with the LCD drive voltage for a four-plex drive. The LCD indicates the UHF frequency group and channel. The LCD also has a battery fuel gauge. A 4.000 MHz oscillator, Y101, provides the operating frequency to the microcontroller. The

29、 oscillator circuit includes C107, C108, R102, and R103, which along with Y101, U106, R112, and C112, form the reset cir- cuit. U106 is the reset integrated circuit (IC) that resets the U103 micro- controller if the 5 V normal operating voltage falls below 3.5 V. R107 is the pull-up resistor for the

30、 U103 programming voltage pin. Memory Section The memory section consists of U101, a non-volatile EEPRAM, that stores current transmitter settings and the mapping of compatible groups and channels. Battery Management Section The battery management section consists of comparator U102. It is used to m

31、easure the effective battery voltage, with reference to +5 V, by measuring the time used to charge a capacitor to a reference threshold of 0.1 Vdc 0.01 Vdc. The battery is checked approximately every 5 seconds. Comparator U102 alternately charges C106 with +5 V refer- ence voltage, then the battery

32、voltage (PLUS signal, test point I109). User Interface Section The user interface section consists of the Power, Mode, and Set switches. The status of each switch function is indicated on the LCD. Power Supply Section The U105 dc-to-dc converter provides the transmitter with regulated +5 V derived f

33、rom two AA batteries. Power MOSFET Q101 provides reverse battery protection. Q103, R118, R286, and C124 control the soft start and reset of dc-to-dc converter following battery voltage drops. Shure U1/U1L Body-Pack UHF Transmitter 525C1021 (BG)Preliminary Tests Preliminary Tests Test Component Locat

34、ions MC68H ABCD Digital Display Board, Side 1 Digital Display Board, Side 2 * *Shorted with a 0 resistor on F board versions and later. Rf-Audio Board, Side 1 Rf-Audio Board, Side 2 * * *On F board versions and later. *On F board versions and later. * Mic-Jack Board, LEMO 4-Pin, Mic-Jack Board, TINI

35、 Q-G 4-Pin, Figure 2.Test Component Locations Shure U1/U1L Body-Pack UHF Transmitter 25C1021 (BG)6Preliminary Tests Listening Test Before completely disassembling the transmitter, operate it to deter- mine whether it is functioning normally and try to duplicate the reported malfunction. Refer to the

36、 User Guide for operating instructions, trouble- shooting, and specifications. Review any customer complaint or request, and focus the listening test on any reported problem. The following, more extensive, functional tests require partial disassembly. Functional Tests Refer to the Disassembly sectio

37、n to partially disassemble the transmitter for the following functional tests. Use dc blocks at all rf outputs to protect test equipment. Test Setup 1.Use a U4 receiver for the following functional tests. 2.Dc voltages are present at most rf test points. Use dc blocks to protect the test equipment,

38、if necessary. 3.Connect the (+) power supply terminal through a milliammeter to the (+) contact on the battery nest, and the () power supply terminal to () the contact on the battery nest. 4.Connect a dc voltmeter across the power supply and set the power supply for +3 Vdc. 5.Connect the audio gener

39、ator to the mic-jack board either via the TINI QG connector, or the LEMO connector to BNC cable, depending on mic style. Rf Power 1.Attach a U4 antenna to the spectrum analyzer. 2.Turn the U1 on and hold it very close to the antenna. Move the U1 up and down to maximize power on the spectrum analyzer

40、. 3.Verify that output power is greater than 3 dBm. Current Drain 1.Apply 3.0 Vdc to the battery terminals. 2.Verify that the current drain is less than 110 mA. Shure U1/U1L Body-Pack UHF Transmitter 725C1021 (BG)Preliminary Tests Frequency Response If the U1 has an attenuator switch on the back of

41、the unit, it should be set to 6 dB for the following tests (versions G or later). Values between board versions may vary slightly; the following values are typical values. 1.With the transmitter set to minimum gain, apply 200 mVrms at 1 kHz to its input. 2.Connect the audio analyzers input to the un

42、balanced output of the U4 receiver. 3.Make sure the receiver volume control is set to maximum. 4.With respect to the 1 kHz level, measure 8.22 dBu 2 dB. 5.Change the frequency to 100 Hz. Verify that the measurement from the U4 unbalanced output is within 2 dB with respect to the 1 kHz level. 6.Chang

43、e the frequency to 10 kHz. Verify that the measurement from the U4 unbalanced output is within 2 dB with respect to the 1 kHz level. Shure U1/U1L Body-Pack UHF Transmitter 25C1021 (BG)8Notes Notes This page intentionally left blank. Shure U1/U1L Body-Pack UHF Transmitter 925C1021 (BG)Disassembly and

44、 Assembly Disassembly and Assembly ATTENTION Observe precautions when handling this static-sensitive device. Disassembly NOTE: All models shipped after February 1999 have a soldered attached antenna to replace the screw-on removable antenna. Do not try to remove and replace the soldered attached ant

45、ennas. 1.Open the battery compartment cover and remove the batteries. 2.Remove the belt clip. 3.Remove the two screws from the back of the case. 4.Lift the top half of the transmitter case away to expose the printed circuit boards. 5.Remove the two screws securing the battery nest to the chassis. 6.

46、Remove the rf ground screw, located next to the antenna. 7.Lift the printed circuit boards out of the case. BELT CLIP BATTERY NEST ANTENNA RF GROUND SCREW TOP COVER BATTERY COMPARTMENT COVER RF-AUDIO CIRCUIT BOARD DIGITAL DISPLAY CIRCUIT BOARD CONDUCTIVE WASHER (SLIPS OVER ANTENNA) RF SHIELDING GASK

47、ET NOTE: All models shipped after February 1999 have a soldered attached antenna to replace the screw-on removable antenna. . Figure 3.U1/U1L Hand-Held Transmitter Disassembly Shure U1/U1L Body-Pack UHF Transmitter 25C1021 (BG)10Disassembly and Assembly Reassembly After completing all repairs, repla

48、ce the antenna. Then place the circuit boards back in the case, making sure the multi-pin connectors on the boards mate. Reassemble the transmitter by performing the steps of the disassembly procedure in reverse order. Shure U1/U1L Body-Pack UHF Transmitter 1125C1021 (BG)Service Procedures Service P

49、rocedures Service Notes Units With Date Codes Earlier Than August 1996 A small number of synthesizer ICs (U204) can experience start-up problems with the 4 MHz crystal reference oscillator. The problem will only occur for certain values of tuning capacitance. The transmitter displays the correct group and channel information. However, the carrier will have moved to its lowest possible frequency (around 750 MHz). The tuning voltage of the VCO will read 0 Vdc. Adjusting the crystals tuning capacitor to its lowest value should cause the 4 MHz crystal oscillator to start up,