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Shure UC2 Service Manual

Hand-held uhf transmitter
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SERVICE MANUAL CHANGE NOTICE
Changes or corrections have been made to this service manual. Update your service manual by replacing
the pages listed in the table below with the ones attached to this change notice.
CHANGES EFFECTIVE [DATE]
these pages from
your current manual
Revision 1
Revision 2
pages:14,15,17,20,22,27,29 and 30
SERVICE MANUAL REVISION HISTORY
Release
Original
Revision 1
Revision 2
Revision 3
E1999, Shure Incorporated
UC2 UHF HAND-HELD TRANSMITTER
REMOVE
ALL
Shure Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
UC UHF Wireless System
the following revised pages
attached to this notice
Revision3
pages:14,15,17,20,22,27,29 and 30
Part Number
25A1044
25B1044
25C1044
25C1044
INSERT
ALL
Revision 2
Date Code
RI
SB
TB
TK
Printed in U.S.A.

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Summary of Contents for Shure UC2

  • Page 1 UC UHF Wireless System SERVICE MANUAL CHANGE NOTICE UC2 UHF HAND-HELD TRANSMITTER Changes or corrections have been made to this service manual. Update your service manual by replacing the pages listed in the table below with the ones attached to this change notice.

  • Page 2: Controls And Connectors

    Figure 1. UC2 Controls and Connectors 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. Licensing: Operation may require a user license. Frequency or power-output modifications may violate this product’s approvals.

  • Page 3: Circuit Description

    RF POWER RF MUTE RF MUTE AUDIO IN Figure 2. UC2 Hand-Held Transmitter Circuit Block Diagram Audio Section FCC-Approved Audio enters L200, an inductor used as an rf choke. The signal is ac coupled through capacitor C200 into a user adjustable gain stage.
  • Page 4 Shure UC2 Hand-Held UHF Transmitter the amplifier and bias circuits from rf interference. Due to its topology, this stage is unique because it is non-inverting and allows for a gain less than unity. Audio then enters a buffer to the pre-emphasis network and the compression stage.
  • Page 5 Shure UC2 Hand-Held UHF Transmitter ETSI-Approved This transmitter uses the same pcb as the domestic system, but it requires a different topology and different parts. A limiter is inserted between the pre-emphasis and the compressor to limit the occupied bandwidth.

  • Page 6: Digital Section

    Shure UC2 Hand-Held UHF Transmitter The pre-driver stage, Q302, provides approximately 6 to 8 dB of gain, which makes up for the pad. R326 and R327 provide base bias for the transistor, while R328 sets its operating current. L303 is an rf choke used to provide power to the stage, while L304, C332, C333, C357, and C2 provide filtering/matching for the stage.
  • Page 7 Shure UC2 Hand-Held UHF Transmitter mapping of the compatible groups and channels. The microcontroller serially communicates with this part via data and clock lines to read the frequency corresponding to the Group and Channel position. The ability to write to the memory occurs during factory programming only.
  • Page 8 Shure UC2 Hand-Held UHF Transmitter For JA frequencies, the Group switch has 16 positions, and the Channel switch has 10 positions. Power Switch and Mute Interface When a transmitter is turned off, the signal goes to logic low PWRDN on U303, pin 19. This immediately disables the tone key, and the power hold circuit automatically kicks in to bypass the power switch.
  • Page 9 Shure UC2 Hand-Held UHF Transmitter Notes This page intentionally left blank. 25C1044 (TK) Notes...

  • Page 10: Functional Test

    ! CAUTION ! Observe precautions when handling this static-sensitive device. Disassembly 1. Remove the microphone cartridge from the UC2. 2. Use a pair of needlenosed pliers to remove the circuit board retaining ring from inside the handle. 3. Push the bezel tab-snap in the handle behind the contact pcb to remove the bezel and switch actuator.
  • Page 11 Handle Gain control access Battery cup Figure 4. UC2 Hand-Held Transmitter, exploded view. Reassembly To reassemble the unit, reverse the disassembly steps given above: 1. Slide the circuit board back into the handle. 2. Reinstall the retaining ring, switch actuator, bezel, and the microphone cartridge.

  • Page 12: Service Procedures

    0 dBV = 2.2 dBu 0 dBu = 0 dBm, assuming the load = 600 Ω 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.
  • Page 13 (CCW). 5. Apply + 9 Vdc across the battery terminals (J201, J202, side 2). 6. Toggle the power switch, S200, to turn on the UC2 transmitter. 7. Set the UC2 Group and Channel switches, S301 and S302, according to the group designators on the board and the settings given in Table 2.
  • Page 14 J201 J200 TP10 Q211 RF SIDE 2 D304 Q305 J301 Q303 C303 D303 TPRF1 D302 C324 C336 L308 D301 TP30 C347 TP+9 U306 C315 U304 J302 C353 L300 J300 Figure 5. UC2 Major Test Component Locations 25C1044 (TK) Test Set-Up...
  • Page 15 Group switch: See Table 2 For Japan models with PCB versions: “N” and earlier connect to J2 (pcb rf side 1) Figure 6. UC2 Frequency Test Set-Up 1. Put a dc voltmeter across TP30 (tuning voltage line) and RF GND 2. Adjust the trimmer, C510, until the voltmeter reading matches the appropriate entry in Table 2, ±...

  • Page 16: Power Output Measurement

    Peak search: ON Signal track: ON Marker: ON Figure 7. UC2 Power Output Measurement Test Set-Up 1. Remove the BNC cable end from the frequency counter and connect it to the 50 Ω input of the spectrum analyzer.. Use the equipment settings shown in Figure 8.
  • Page 17 Shure UC2 Hand-Held UHF Transmitter Deviation Deviation must be set to make sure the companding systems be- tween the transmitter and receiver correctly track each other. The level coming out of the transmitter’s audio compressor must match the level going into the receiver’s audio expander. A fixed gain structure does not ensure an exact match, primarily because of variations in voltage- controlled oscillators (VCOs).
  • Page 18 2. Reassemble the printed circuit boards. Use a PT1840 test head and brass ring (PT1838-Y) to connect the audio analyzer to the UC2 audio input (J205). Turn ON the Low-Pass (30 kHz) and High-Pass (400 Hz) filters on the audio analyzer.
  • Page 19 5. Connect the unbalanced output of the UC4 to the input of the audio analyzer (ac voltmeter). 6. Take a radiative measurement by holding the battery of the UC2 next to the receiver’s antenna. 7. Turn the transmitter ON and adjust R320 until the ac voltmeter on the receiver reads the same as the deviation reference voltage, measured above, ±...
  • Page 20 Shure UC2 Hand-Held UHF Transmitter Option 2 – Using a Modified SC4 IF Receiver Deviation tests can also be performed using a modified SC4 IF receiver. For instructions on modifying an SC4 receiver, consult the Shure Service Equipment manual. Reference Voltage 1.
  • Page 21 4. Turn the UC2 power back ON. 5. Adjust the audio analyzer output level (typically = –2.2 dBu) to measure the following at TPA4 (U201, pin 7) :...
  • Page 22 Shure UC2 Hand-Held UHF Transmitter 6. Connect the UC2 rf output test cable BNC end to the input port (R) of the Zad-1 mixer. 7. Connect the rf signal generator, and set the frequency to the operating frequency (from Table 2) minus 10.7 MHz.

  • Page 23: Product Specifications

    Shure UC2 Hand-Held UHF Transmitter Product Specifications After tuning, the unit should meet the following specifications. Specification Minimum Typical Maximum Current drain 50 mA 60 mA 70 mA Frequency –1.0 kHz See Table 2 +1.0 kHz Audio freq response @ 100 Hz wrt 1 k –5.0 dB...
  • Page 24 Shure UC2 Hand-Held UHF Transmitter Bench Checks Dc Problems Make all dc measurements with respect to the rf ground unless otherwise specified. Connect the rf and audio printed circuit boards together via the 11 pin connector, the battery contacts, and the “D” board.
  • Page 25 Shure UC2 Hand-Held UHF Transmitter Low Rf Output Power n Check the polarity/soldering of the output low-pass filter, U1. (Rf IN is marked with a dot.) n Check for opens or shorts on output coil L308. n Check the polarity of Q304.

  • Page 26: Audio Problems

    Shure UC2 Hand-Held UHF Transmitter Audio Problems No Tone Key No tone key means that the 32.768 kHz tone key sidebands are not visible when the carrier is viewed on a spectrum analyzer. If tone key levels are there but are too low, the deviation is off and needs to be recalibrated.
  • Page 27 Shure UC2 Hand-Held UHF Transmitter Notes This page intentionally left blank. 25C1044 (TK) Notes...

  • Page 28: Parts Designations

    Shure UC2 Hand-Held UHF Transmitter Replacement Parts and Drawings Parts Designations The following comments apply to the parts list and the schematic: Resistors: Unless otherwise noted, all resistors are surface-mount 0603 size, with rating and 1% tolerance. Capacitors: Unless otherwise noted, non-polarized capacitors are...
  • Page 29 Shure UC2 Hand-Held UHF Transmitter Table 5 Printed Circuit Board Replacement Parts Reference Shure Part Designation Description Number C314 Capacitor, trim, 5 – 40 pF 152F03 C510 Capacitor, trim, 1 – 3 pF 152A04 D201 Diode, signal / switching, SMD, SOT-23, 1.1 V...
  • Page 30 Shure UC2 Hand-Held UHF Transmitter Table 6 Group Designators (in order by frequency) Frequency Country Country Range Designation Code kΩ kΩ kΩ kΩ kΩ kΩ (MHz) 774–782 Netherlands – – – – – 782–806 U. S. & Canada – –...
  • Page 31 Shure UC2 Hand-Held UHF Transmitter Table 7 Frequency Dependent Parts (in order by frequency) Frequency Country Country C210 C211 C254 C330 C345 Range (MHz) Designation Code 774–782 Netherlands .047 – – – 782–806 U. S. & Canada – – –...
  • Page 32 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK) Parts Designations...
  • Page 33 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK) Replacement Parts and Drawings...
  • Page 34 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK) Parts Designations...
  • Page 35 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK) Replacement Parts and Drawings...

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