Shure T4 Service Manual
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Shure T4 Service Manual

Diversity receiver
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SERVICE MANUAL CHANGE NOTICE
Changes and corrections have been made to the Service Manual for the T4 Receiver. 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 below.
T4 RECEIVER SERVICE MANUAL REVISION HISTORY
Release
Original
Revision 1
Revision 2
Revision 3
Revision 4
Revision 5
CHANGES EFFECTIVE
REMOVE
these pages from the
T4 Service Manual
E1999, Shure Incorporated
25–1020–1 (EA)
T4 DIVERSITY RECEIVER
Part Number
25A1020
25B1020
25C1020
25C1020
25C1020
25C1020
JANUARY 13, 2005
21 & 22
Shure Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
T Wireless System
Date Code
QG
SB
SI
TF
CC
EA
these new Revision pages into the
T4 Service Manual
Color
White
Pink
White
White
White
Red
INSERT
21 & 22
Printed in U.S.A.

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  • Page 1 SERVICE MANUAL CHANGE NOTICE T4 DIVERSITY RECEIVER Changes and corrections have been made to the Service Manual for the T4 Receiver. To update your Service Manual, remove the pages identified in the tables below and replace them with the pages attached to this Change Notice.
  • Page 2 Service Manual 25C1020 (EA) T4 Diversity Receiver Characteristics General This manual tells how to service and align the Shure T4 Diversity Receiver (Figure 1). This single-channel, crystal-controlled unit operates within the z to 238 band. VHF-FM Á Á Á Á Á Á Á Á Á Á Á...

  • Page 3: Circuit Description

    Shure T4 Diversity Receiver Circuit Description The Shure Model T4 is a single-conversion superheterodyne diversity receiver operating in the 169–238 z band. It is intended for use with the matching Shure T Series wireless transmitters. Stages Two complete, independent sections provide diversity reception. Signals enter via the single-element, quarter-wave antennas.

  • Page 4: Audio Output

    Shure T4 Diversity Receiver Channel B: This follows an identical scheme: noise signals from U2 are ad- justed by squelch level control R41 before being amplified by U108C, filtered by U108A, rectified by D107, and smoothed by C140. Comparator Circuits U106C and U106D compare the dc noise signals from the two channels.
  • Page 5 Shure T4 Diversity Receiver Notes Notes 25C1020 (EA)

  • Page 6: Preliminary Tests

    Shure T4 Diversity Receiver Preliminary Tests Listening Tests Before disassembling the unit, operate it to determine whether it is function- ing normally. First and most important: Review the customer’s complaint (if avail- able) and focus your tests on the problem. If this proves inconclusive or you want somewhat more extensive checks, perform the following functional tests.
  • Page 7 Shure T4 Diversity Receiver ters. The receiver’s Volume control should still be in its maximum posi- tion. Tests 1. Verify the following receiver measurements: , "90 mV. Record your measurement as a Audio level is 400 mV reference level for the next two steps.

  • Page 8: Disassembly And Assembly

    Shure T4 Diversity Receiver Disassembly and Assembly To access the printed circuit (pc) board, disassemble the receiver. CAUTION Observe precautions when handling this static-sensitive device. Disassembly 1. Disconnect all power to the receiver. 2. Collapse the antennas and rotate them until they lie flat against the case.

  • Page 9: Antenna Replacement

    Shure T4 Diversity Receiver Antenna Case top Circuit board Case bottom É É É É Volume knob Mounting screw Figure 3. Reassembly 1. Slide the Volume knob back on: note how it is keyed to the flat part of the shaft.

  • Page 10: Service Procedures

    Shure T4 Diversity Receiver Service Procedures Reference Material The Shure Wireless System T Series User’s Guide provides a description of the unit as well as operating instructions, troubleshooting suggestions, and tech- nical data. Special Equipment and Tools In addition to the standard items described in the Service Equipment manual,...
  • Page 11 Shure T4 Diversity Receiver Table 2 -Approved Operating Frequencies Group Crystal Code Freq. ( 169.445 171.845 176.200 177.600 182.200 183.600 186.200 192.200 202.200 208.200 Table 3 -Approved Operating Frequencies ETSI Group Crystal Code Freq. ( 173.800 174.100 174.500 174.500 174.800 175.000...

  • Page 12: Changing The Frequency

    Shure T4 Diversity Receiver Changing the Frequency The operating frequency of the T4 Receiver may be changed within a specif- ic group by changing the crystal on the pc board (for group information, see the preceding section). Check the receiver for proper operation before attempting to change its operating frequency.

  • Page 13: Display Check

    Shure T4 Diversity Receiver Presettings Most field units should already be tuned closer to the desired settings than these approximations. However, you may need to preset units when you are changing the frequency or an coil, or when an unskilled person has attempted to retune them.
  • Page 14 Shure T4 Diversity Receiver Antenna B Group designator U101 (see Table 1) D108 C150 XLR audio output D109 connector (J102) C145 Note: Used only on R168 Presenter and Vocal Phone jack Artist models !/4-in. (J101) U108 L108 C118 Edge of...
  • Page 15 Shure T4 Diversity Receiver Coil Adjustments Each channel has to be adjusted separately. A: Channel A 1. Disconnect the power to the receiver. Mute Channel B by grounding 7 (pin 14 of U106). Reconnect the power. 2. Adjust the signal generator’s...
  • Page 16 Shure T4 Diversity Receiver 2. Connect power to the receiver. 3. Adjust the output of the signal generator output so that you obtain a reading of approximately 2 Vdc at 4. If this is unattainable even with the full –20 dBm generator output, adjust coil L7 until you obtain a reading above 2 V.
  • Page 17 Shure T4 Diversity Receiver Bench Checks Note: In this section, test points for Channel A are given first, and the corre- sponding test points for Channel B are enclosed in square brackets. Power n Check for 9 Vdc (±0.35 Vdc) at...
  • Page 18 Shure T4 Diversity Receiver signal is present. If you obtain different results, compare the dc voltages at U106, U107 (earlier units only), U103, and U105 [U108] with those of a prop- erly working unit, or replace the pc board. n If the muting circuit works but has insufficient adjustment range, set the generator for a –95 dBm signal and check...
  • Page 19 Shure T4 Diversity Receiver n If you cannot set the audio level properly with R106 [R168], make sure that the other diversity channel is squelched: only one channel should be acti- vated during this adjustment. n If you can set the audio levels properly for each channel while the other is squelched, but these levels change significantly when both channels are ac- tivated, check U103.
  • Page 20 Shure T4 Diversity Receiver Notes: 25C1020 (EA) Notes:...

  • Page 21: Product Changes

    On the pages following the parts list are the drawings of the printed circuit boards and the schematics. Product Changes This section briefly describes significant changes to the T4. Op Amps: The older part for U105, U108, and U109 (manufactured by Ray- theon) was replaced. No other component changes were involved.

  • Page 22: Parts Designations

    Shure T4 Diversity Receiver Parts Designations The following comments apply to the parts list and the schematic: Resistors: All resistors are surface-mount with rating and 1% toler- ance. Capacitors: Unless otherwise noted, non-polarized capacitors are surface- mount dielectric types with a 100 capacity and a 5% tolerance, and polar- ized capacitors are tantalum types.
  • Page 23 Shure T4 Diversity Receiver D101,107,110, Diode, Signal, Switching, SOT–23, 100VDC 184A08 111,112,113 (MMBD7000L) D108, 109 Rectifier, Silicon, 140VDC 184A20 3, 5, 6 Ceramic Filter, 10.7MHz 86A8910 J101 Phone Jack, Stereo, Right Angle, -inch 95A8329 J102 connector (Vocal units only) 95A8400...
  • Page 24 Shure T4 Diversity Receiver In the following four-part table, “Grp” is the board’s frequency group, and “Desig” is the number of the resistor that designates the Group Number. The parts are listed across the tables in alphanumeric order. All capacitor tolerances are in picofarads.
  • Page 25 Shure T4 Diversity Receiver Frequency-Dependent Parts III Grp C55 C77, C78 A 12 pF 15 pF 1 pF (0.1) 12 pF Not used 3.3 pF (0.1) B 12 pF 15 pF Not used 10 pF 1 pF (0.1) 3.3 pF (0.1)
  • Page 26 Shure T4 Diversity Receiver Figure 5. T4 Receiver Pc Board, Component Side 25C1020 (EA) Replacement Parts and Drawings...
  • Page 27 Shure T4 Diversity Receiver Figure 6. Earlier Version of T4 Receiver Pc Board, Side 1 Replacement Parts and Drawings 25C1020 (EA)
  • Page 28 .001 C153 C152 N198 N196 10 µF 100 µF Green R7 = R36 = 33.2Ω L105 U104A 95A8519 T4 Schematic C40 = 10 pF C155 162A12 .001 **R174 and R175 are only used with the Harris FM Detector. (from 90-8550E-11)
  • Page 29 10 kΩ C153 C152 .001 µF 10 µF 100 µF Green L105 U104A On first production: T4 Schematic C155 95A8519 162A12 R17 = R45 = 49.9 Ω .001 µF R7 = R36 = 33.2 Ω (from 90-8550F-11) C40 = 10 pF...
  • Page 30 183A23 150pF Ceramic Filter 270pF 82A8003 82A8003 15pF* .047 TP4B 56pF* 7.5K TP2B .047 12pF* .001 .047 .001 Audio .047 .001 .047 82A8003 .047 82A8003 37.4K T4 Earlier Version Schematic 1999, Shure Brothers Inc. (page 1 of 2) 27C1020 (SB)
  • Page 31 1.0K C153 UA7809C C152 .001 N197 R168 100uF R17=R45=49.9 ohms and N198 10uF N196 Green R7=R36=33.2 ohms RC4156M L105 95A8519 C40=10 pF 162A03 C155 U104 .001 T4 Earlier Version Schematic 1999, Shure Brothers Inc. (page 2 of 2) 27C1020 (SB)

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