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Shure UC2 Service Manual

Uhf, hand-held
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See also: User Manual
Characteristics
General
Controls and Connectors
1. Mic Cartridge Grille (87 shown)
2. Battery Fuel Gauge LEDs
3. Power ON/OFF Switch
4. Audio Gain Control
1998, Shure Brothers Inc.
25A1044 (RI)

Service Manual

UHF Transmitter
The Shure UC2 Hand-Held UHF Transmitter is a microprocessor-
controlled microphone transmitter, operating in the 774 to 862 MHz
frequency range. The UC2 hand-held transmitter is used in mid-level
installed sound, rental, and concert sound applications. Six frequency
range variations are available.
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.
UC2 Hand-Held
8
7
5. 9 V Battery
6. Battery Cup
7. Group Selection Rotary Switch
8. Channel Selection Rotary Switch
1
2
3
4
5
6
Printed in U.S.A.

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Summary of Contents for Shure UC2

  • Page 1: Service Manual

    The Shure UC2 Hand-Held UHF Transmitter is a microprocessor- controlled microphone transmitter, operating in the 774 to 862 MHz frequency range. The UC2 hand-held transmitter is used in mid-level installed sound, rental, and concert sound applications. Six frequency range variations are available.

  • Page 2: 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 3 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 4 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 5: Digital Section

    Shure UC2 Hand-Held UHF Transmitter output is also coupled to the pre-driver and rf power amplifier through a resistive network (R322, R324, R325) and a coupling capacitor, C329. 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.
  • Page 6 Shure UC2 Hand-Held UHF Transmitter Memory Section The memory section consists of U302, a non-volatile, Electrically Erasable/Programmable Read Only Memory ( ) that stores the EEPROM 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.
  • Page 7 Shure UC2 Hand-Held UHF Transmitter Any switch change is comprised of state toggle from odd to even, and vice versa. Only this change is detected, and it is followed by a multiplexed switch read, in which U303, pins 7 and 8, become selectively grounded outputs to read the selected switch’s state on pins 3 through 6.
  • Page 8 Shure UC2 Hand-Held UHF Transmitter Notes This page intentionally left blank. Notes 25A1044 (RI)

  • Page 9: 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 10 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 11: 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 12 C353 L300 J300 Figure 5. UC2 Major Test Component Locations 1. Use the PT1843 cable to connect the audio board to the rf board through the 11-pin board interconnects (J200, J300, side 2). 2. Apply + 9 Vdc across the battery terminals (J201, J202, side 2).
  • Page 13 Shure UC2 Hand-Held UHF Transmitter Table 2 lists the group carrier frequencies, switch settings, and tuning voltages for all the alignment tests that follow. Table 2 Group Carrier Frequencies and Tuning Voltages (in order by carrier frequency) Group Channel Carrier...
  • Page 14 J2 is only placed on the JA, JB frequency assemblies. 2. 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 15 Connect to J2 Connect to J2 Group switch: See Table 2 (pcb rf side 1) Figure 7. 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, 0.125 Vdc.

  • Page 16: Power Output Measurement

    Peak search: ON Signal track: ON Marker: ON Figure 8. 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 Reference Voltage, Using a UC4 or U4S Receiver 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.
  • Page 18 Shure UC2 Hand-Held UHF Transmitter Deviation Adjustment Voltage: Using a UC4 or U4S Receiver AUDIO ANALYZER S501 (TONE KEY SWITCH) AUDIO SIDE 1 TPA4 – U201, pin 7 UC4 Receiver UC2 Transmitter Audio Analyzer Output: Unbalanced Power: + 9 Vdc...
  • Page 19 4. Connect the unbalanced output of the UC4 to the input of the audio analyzer (ac voltmeter). 5. Connect the BNC end of the cable from the rf output of the UC2 to the antenna input of the UC4 through a 20 dB in line pad.
  • Page 20 Shure UC2 Hand-Held UHF Transmitter Deviation Reference Voltage: 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. ZAD–1 MIXER...
  • Page 21 4. Turn the UC2 power back ON. 5. Adjust the audio input level using the audio analyzer output to measure the following at TPA4 (U201, pin 7) :...
  • Page 22 Figure 14. Deviation Adjustment Voltage Test Set-Up, Steps 6 through 8, Using a Modified SC4 IF Receiver 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 Notes This page intentionally left blank. Notes 25A1044 (RI)
  • Page 25 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 26 Shure UC2 Hand-Held UHF Transmitter Low Rf Output Power Check the polarity/soldering of the output low-pass filter, U1. (Rf IN is marked with a dot.) Check for opens or shorts on output coil L308. Check the polarity of Q304. Verify the dc bias of Q302 and Q304. Check L303, L304, and L306, if no bias.

  • Page 27: 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 28 Shure UC2 Hand-Held UHF Transmitter Notes This page intentionally left blank. Notes 25A1044 (RI)

  • Page 29: 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 30 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 31 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 32 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 33 Shure UC2 Hand-Held UHF Transmitter 25A1044 (RI) Replacement Parts and Drawings...
  • Page 34 Shure UC2 Hand-Held UHF Transmitter Replacement Parts and Drawings 25A1044 (RI)

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