Shure Incorporated 222 Hartrey Avenue Evanston IL 60202-3696 U.S.A. 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.
Service Manual UC2 Hand-Held UHF Transmitter 25C1044 (TK) Characteristics General The Shure UC2 Hand-Held UHF Transmitter is a microprocessorcontrolled microphone transmitter, operating in the 692 to 716 MHz and 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. Controls and Connectors 1 2 3 8 4 5 7 6 1. Mic Cartridge Grille (87 shown) 5. 9 V Battery 2.
Shure UC2 Hand-Held UHF Transmitter Circuit Description LIMITER CONTROL INPUT Σ MIC REG. +5v BATTERY MGMT. & FUEL GAUGE TONE KEY 32.768 kHz FROM ON / OFF BATT. SWITCH TONE KEY LIMITER CONTROL OUTPUT +5V CIRCUIT AUDIO OUT CALL ID UNREG. PWR. TONE CONTROL 4 MHz PWR. OFF DETECT MCU PLL CONTROL FET BYPASS EEPROM (MEM) MC68HC705 PWR. CONTROL HOLD 4 MHz CIRCUIT SYNTH. MB15A02 GROUP RF POWER RF MUTE CHANNEL RF MUTE AUDIO IN VCO Figure 2.
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. R213, R214, and C211 set up two corners for the pre-emphasis network. The pre-emphasis boosts the high frequencies before transmission. This network feeds an NE575 compander, U202, that utilizes an external amplifier, U201B.
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. The buffer after the gain stage, U201A, is now an inverter with pre-emphasis and 20 dB of attenuation. Previously bypassed, the expander side of the NE575 (U202) is now activated and used as a limiter.
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. The collector of Q302 feeds into the power amplifier stage via coupling capacitor C338 and a pi-matching network made up of C339, L305, and C340.
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. During normal usage, this memory is used as a look-up table only.
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 PWRDN signal goes to logic low on U303, pin 19. This immediately disables the tone key, and the power hold circuit automatically kicks in to bypass the power switch. This is followed by 500 mS of delay, and then the rf is muted and turned off.
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Shure UC2 Hand-Held UHF Transmitter Functional Test Verify operation and reported malfunction, referring to the product User’s Guide for a description of the unit as well as information on its operation, troubleshooting, and technical data. Disassembly and Assembly ! 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.
Shure UC2 Hand-Held UHF Transmitter Á Ball screen Retaining ring Contact board Á ÁÁÁ ÁÁÁ ÁÁÁ ÁÁÁ Microphone cartridge (SM58 shown) Bezel Audio circuit board Gain control Rf circuit board ÁÁÁ ÁÁÁ Handle Gain control access Switch actuator 9 Vdc alkaline battery ÁÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ ÁÁÁÁ ÁÁÁÁ ÁÁÁ Á Á ÁÁÁÁ 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.
Shure UC2 Hand-Held UHF Transmitter Service Procedures Measurement Reference dBu is a measure of voltage, and dBm is a measure of power. For example, the HP8903 should be labeled dBu instead of dBm because it is a voltage measurement. These two terms are often used interchangeably even though they have different meanings. Audio levels in dBu are marked as dBm on the HP8903. dB Conversion Chart 0 dBV = 2.
Shure UC2 Hand-Held UHF Transmitter Test Set-Up 1. Desolder the printed circuit boards (pcbs) and pull them apart. When the pcbs are desoldered, leave the battery contacts soldered to the audio board for powering up the unit. 2. Remove C347 and connect the respective RF test cable between TPRF1 / RF GND and a frequency counter.For Japan models with PCB version “N” and earlier, do not remove C347. Connect a 95C8418 cable between J2 and the frequency counter. 3.
Shure UC2 Hand-Held UHF Transmitter AUDIO SIDE 1 TP18 U200 Q203 +9V C214 C222 +5V Q213 C216 Q212 Q202 U202 S200 R7 U201 Q201 Q204 U205 Q220 Q209 TP4 C291 J205 C27 P200 R39 PAD TP6 Y200 TP10 L2 C200 R25 D201 1 P201 U203 GND 1 RED RF SIDE 1 RF GND* S302 U302 R40* P204 VCO R320 Adj Q304 GREEN TP30 C308 U501 C314 Y302 L302 S301 C309 C510 U311 J2* TPRF1 U303 P203 Y301 Q301 TP+9 *J2 and R40 are placed for JA, JB frequencies only.
Shure UC2 Hand-Held UHF Transmitter Alignment Frequency Use this service procedure to correctly align the transmitter’s operating (output) frequency. C510 tunes the voltage-controlled oscillator (VCO) to the operating frequency selected, with a 1 – 4 Vdc tuning range. C314 adjusts the reference oscillator on the synthesizer, U304.
Shure UC2 Hand-Held UHF Transmitter Power Output Measurement The output power measurement ensures that the output signal is strong enough for sufficient range when the system is in use. The output power measurement also verifies that the output power is not above the specified maximum level, to ensure compliance with regulatory agencies standards.
Shure UC2 Hand-Held UHF Transmitter Deviation Deviation must be set to make sure the companding systems between 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 voltagecontrolled oscillators (VCOs).
Shure UC2 Hand-Held UHF Transmitter Adjustment Voltage 1. Remove the RF test cable from TPRF1 and GND, and replace C347. For Japan models PCB version “N” and earlier remove cable from J2. 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.
Shure UC2 Hand-Held UHF Transmitter Tone Key (S501): ON Channel switch: See Table 2 Low-Pass (30 kHz): ON High-Pass (400 Hz): ON Figure 9. Deviation Adjustment Voltage Test Set-Up, Using a UC4 or U4S Receiver 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.
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. See Figure 12 for equipment test set-up and equipment settings. 2. Connect the rf signal generator output to the input port (L) of a Zad-1 mixer 3.
Shure UC2 Hand-Held UHF Transmitter Adjustment Voltage 1. Disconnect the rf signal generator from the SC4 IF receiver. 2. Set the SC4 tone key switch on the SC4 front panel to ON. 3. Connect the audio analyzer output to the MIC input of the transmitter, using the test head or clip leads to the gold spring contacts. 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) : UA, UB –6.8 dBu ± 0.
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. 8. Turn ON the UC2 and adjust R320 until the audio voltmeter connected to the unbalanced output of the UC4 reads the same as the deviation reference voltage, measured above, ± 0.1 dB, or ± 0.2 dB for JA, JB frequencies..
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 –4.0 dB –3.0 dB Audio freq response @ 10 KHz wrt 1 k +8.0 dB +9.0 dB +10.0 dB 95.0 dB 100.0 dB – 14.0 dBm 16.0 dBm 17.0 dBm 80.0 dB 85.0 dB – 14.0 dBm 16.0 dBm 17.0 dBm 80.0 dB 85.0 dB – 12.
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. n Make sure the battery voltage is between 6 and 9 Vdc. Make sure TP+9 has this voltage. Check for the correct Vcc and +5 V rf at Q301. If incorrect voltage is present: n Trace the dc back to the voltage regulator.
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. n Verify the dc bias of Q302 and Q304. Check L303, L304, and L306, if no bias. Verify that the rf MUTE signal changes from 0 Vdc at power up and power down to +5 Vdc during normal operation.
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. They should be, roughly, –23 dBc ± 3 dB. n Apply a 1 kHz tone at a level of 0 dBu to the audio input with the audio gain pot at minimum.
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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 1/10 W rating and 1% tolerance. Capacitors: Unless otherwise noted, non-polarized capacitors are surface-mount NPO dielectric types with a 100 V capacity and a 5% tolerance, and polarized capacitors are tantalum types.
Shure UC2 Hand-Held UHF Transmitter Table 5 Printed Circuit Board Replacement Parts Reference Designation C314 Description Capacitor, trim, 5 – 40 pF Shure Part Number 152F03 C510 Capacitor, trim, 1 – 3 pF 152A04 D201 Diode, signal / switching, SMD, SOT-23, 1.
Shure UC2 Hand-Held UHF Transmitter Table 6 Group Designators (in order by frequency) Frequency Range (MHz) Country Designation Country Code R19 kΩ R20 kΩ R21 kΩ R22 kΩ R26 kΩ R27 kΩ 774–782 Netherlands MC – 1.0 – – – – 782–806 U. S. & Canada UA 1.0 – – – – – 692–716 U.S. UB – – – – – 1.0 797–806 Japan JA – – 1.0 – – – 800–830 Europe MB/MD – 1.0 – – – – 806–810 Japan JB – – – 1.0 – – 838–862 England KK – – – – 1.
Shure UC2 Hand-Held UHF Transmitter Table 7 Frequency Dependent Parts (in order by frequency) Frequency Range (MHz) Country Designation Country Code C4 uF C24 uF C35 pF C210 uF C211 uF C254 uF C330 pF C345 pF 774–782 Netherlands MC .047 0.1 220 2.2 – – – 27 782–806 U. S. & Canada UA – – – – .047 – – 27 692–716 U. S. UB – – – – .047 – n/a n/a 797–806 Japan JA .047 0.1 220 2.2 – – 10 4.7 800–830 Europe MB/MD .047 0.1 220 2.
UC2 Hand-Held UHF Transmitter Printed Circuit Board, Side 1 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK) 31 Parts Designations
UC2 Hand-Held UHF Transmitter Printed Circuit Board, Side 2 Shure UC2 Hand-Held UHF Transmitter Replacement Parts and Drawings 32 25C1044 (TK)
25C1044 (TK) 33 Version K UC2 Hand-Held UHF Transmitter Printed Circuit Board, Side 1 Shure UC2 Hand-Held UHF Transmitter Parts Designations
Replacement Parts and Drawings 34 Version K UC2 Hand-Held UHF Transmitter Printed Circuit Board, Side 1 Shure UC2 Hand-Held UHF Transmitter 25C1044 (TK)
