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Shure UC2 Hand-Held UHF Transmitter

Bench Checks

27

25A1044 (RI)

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.

n

If the carrier on the spectrum analyzer does not show any devi-

ation, check part integrity and audio path continuity between
U201, pin 14, and the VCO.

n

If the spectrum analyzer shows a deviated carrier, probe for a 

32 kHz signal at TPA6 and I209 and continue to the next step.

n

If there is a signal at I209 but not at TPA6, then the mute circuit

through Q211 is being activated.  Verify that the logic signal at
Q211, pin 1, is logic low.  If it is low, replace Q211.  If it is not low,
check the line for a short to +5 V.  If there is no short, the micro-
processor is defective and must be replaced.

n

If there is a 32 kHz signal at both I209 and TPA6, replace R236.

n

If there is not a 32 kHz signal at either I209 or TPA6, there is

something wrong with the tone key circuit or the tone key supply
voltage.  If the tone key supply voltage (U200, pin 8) is less than
2 V, there is a problem with one or more of the following com-
ponents:  R261, R264, R265, R266, C238, Q220, C237, R232,
or R260.

n

If the voltage at U200, pin 8, is greater than 2 V, the problem is in

the tone key circuit itself.  Check for shorts and opens.  Replace
parts in this circuit beginning with the crystal until the 32 kHz 
oscillation returns.

No Audio

n

View the carrier on the spectrum analyzer.  If there are not 

32 kHz tone key sidebands around the carrier, follow the steps
above for “No Tone Key.”

n

9 V, half-supply bias, and ground connections to U200.

n

9 V, half-supply bias, and ground connections to U201.

n

Follow the audio path from where audio is applied until the point

of discontinuity is reached and replace the appropriate part.

Содержание UC2

Страница 1: ...nd rental and concert sound applications Six frequency range variations are available Controls and Connectors 1 Mic Cartridge Grille 87 shown 2 Battery Fuel Gauge LEDs 3 Power ON OFF Switch 4 Audio Gain Control 5 9 V Battery 6 Battery Cup 7 Group Selection Rotary Switch 8 Channel Selection Rotary Switch Figure 1 UC2 Controls and Connectors 1 2 3 4 8 7 5 6 Service Note Shure recommends that all ser...

Страница 2: ...d Transmitter Circuit Block Diagram 32 768 kHz 4 MHz 4 MHz MB15A02 MC68HC705 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 Resistors R202 and R203 set up a half supply bias and R204 sets the input impedance for the stage The back to back diodes D201 are used to keep the op amp from snap...

Страница 3: ...key signal is present with the transmitted signal If the tone key or the transmitter is turned off the receiver will be muted The tone key squelch eliminates receiver noise associated with loss of a carrier Q211 acts as a switch for toggling the tone key MUTE UNMUTE it is controlled via the microprocessor The tone key signal along with the processed audio signal is then fed to a summing amplifier ...

Страница 4: ...he need for multiplier stages and results in a much higher degree of spectral purity The VCO is shielded to prevent external rf fields from affecting its operation Regulated 5 Vdc power from the low drop out regulator U311 is provided to ensure frequency stability with changes in battery voltage The VCO is capable of tuning from 782 to 806 MHz FCC approved with a 1 to 4 V tuning voltage range At t...

Страница 5: ...s filter output couples to the printed circuit board pcb via C347 and L308 The transmitter can deliver 17 dBm 50 mW maximum to the antenna for domestic frequencies JA and JB frequency transmitters can deliver 10 dBm maximum to the antenna During transmitter power up and frequency selection the rf power is muted by bringing the gates of Q303 Q305 low This provides approximately 45 dB rf attenuation...

Страница 6: ...s 14 2 0 mA and the battery fuel gauge is not functional Turning off the power switch completely shuts off the transmitter The audio circuit description section provides information for the battery fuel gauge circuit description Rotary Switches for Frequency Selection A 10 position Group switch S302 and a 16 position Channel switch S301 select the transmitter frequency Both rotary switches share t...

Страница 7: ...ne key and rf mutes This mutes the audio in the receiver to allow a quiet change to another frequency 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 t...

Страница 8: ...Shure UC2 Hand Held UHF Transmitter 8 Notes 25A1044 RI Notes This page intentionally left blank ...

Страница 9: ...ecautions 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 4 Slide the circuit board out by pushing on the battery connectors Right side view o...

Страница 10: ...ard Gain control Audio circuit board Bezel Switch actuator 9 Vdc alkaline battery Rf circuit board Gain control access Battery cup Handle Figure 4 UC2 Hand Held Transmitter exploded view Retaining ring 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 car...

Страница 11: ... Type Model Audio analyzer Hewlett Packard 8903B Digital multimeter Fluke 87 Rf signal generator Hewlett Packard 8656B Frequency counter Hewlett Packard 53181A Spectrum analyzer domestic Hewlett Packard 8590L Spectrum analyzer JA JB Hewlett Packard 8591E Shure UC4 receiver Shure UC4 Test head PT1840 Brass ring for use with test head PT1838 Y BNC to rocket launch cable 95C8418 1 Audio levels in dBu...

Страница 12: ...Q208 Q3 Q2 U2 L1 Q1 C243 L207 TP2 TP16 TP6 TP4 TP10 C213 TP18 9V 5V J200 J300 D304 D303 D302 D301 U5 C303 C324 U306 C353 U304 C315 C336 Q305 Q303 L300 U1 U1 C347 L308 TPRF1 TP30 TP 9 1 1 R39 P201 P200 P203 P204 L2 R25 J2 and R40 are placed for JA JB frequencies only RF GND is accessed thru a hole in the pcb Figure 5 UC2 Major Test Component Locations 1 Use the PT1843 cable to connect the audio boa...

Страница 13: ...ll the alignment tests that follow Table 2 Group Carrier Frequencies and Tuning Voltages in order by carrier frequency Group Group Code Group Switch S101 Channel Switch S102 Carrier Frequency MHz VCO Tuning Voltage TP130 Deviation kHz UA A 4 0 805 500 3 7 45 MB B 1 3 805 500 2 2 15 JA C 0 2 805 500 3 7 5 JB D 4 2 807 500 3 8 5 KK E 5 5 857 125 2 9 15 MC ...

Страница 14: ... ON For JA JB frequencies Connect to J2 High Pass 400 Hz ON Connect to J2 pcb rf side 1 Figure 6 UC2 Frequency Alignment Set Up 1 Remove C347 and connect a 50 Ω cable between TPRF1 RF GND and a frequency counter For JA JB frequencies do not remove C347 Connect a rocket launch cable between J2 and the frequency counter J2 is only placed on the JA JB frequency assemblies 2 Use a PT1840 test head and...

Страница 15: ...mitter Frequency Counter DC Voltmeter Power ON 9 Vdc Operating freq See Table 2 Connect TP30 Operating freq See Table 2 Connect CH 2 TPRF1 and GND Connect RF GND Channel switch See Table 2 For JA JB frequencies Connect to J2 Group switch See Table 2 Connect to J2 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 VCO trimme...

Страница 16: ...ctrum Analyzer Power ON Frequency See Table 2 Operating freq See Table 2 Span 200 MHz Reference voltage 20 dBm 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 2 Measure the output power The output pow...

Страница 17: ...LTAGES ARE PRESENT AT MOST RF TEST POINTS USE A DC BLOCK ON THE RF SIGNAL GENERATOR TO PROTECT TEST EQUIPMENT UC4 Receiver Audio Analyzer Rf Signal Generator Output Unbalanced Measurement AC level INT FM Gain Maximum Filters INT 1 kHz Squelch Mid Low Pass 30 kHz ON Output amplitude 60 dBm Tone Key S501 OFF High Pass 400 Hz ON Frequency See Table 2 Group switch See Table 2 Modulation See Table 2 Ch...

Страница 18: ...Test Set Up Using a UC4 or U4S Receiver Steps 1 through 3 Reassemble the printed circuit boards for this test 1 Disconnect the rf signal generator from the UC4 receiver and return the UC4 tone key switch to the ON position 2 Connect the audio analyzer output to the MIC input of the transmitter using the test head or clip leads to the gold spring contacts 3 Adjust the audio input level using the au...

Страница 19: ...Tone key S501 ON Low Pass 30 kHz ON High Pass 400 Hz ON Figure 11 Deviation Reference Voltage Test Set Up Steps 4 through 6 Using a UC4 or U4S Receiver 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 6 Turn the transmitter ON and ad...

Страница 20: ...mum Filters INT 1 kHz Squelch Mid Low Pass 30 kHz ON Output amplitude 7 dBm Tone Key switch OFF High Pass 400 Hz ON Frequency 10 7 MHz Operating freq See Table 2 Modulation See Table 2 Figure 12 Deviation Reference Voltage Test Set Up Using a Modified SC4 IF Receiver 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 Z...

Страница 21: ...Modified SC4 IF Receiver 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 input level using the audio analyzer output to measure the following at ...

Страница 22: ...C level INT FM Gain Maximum Gain Minimum Output 1 kHz INT 1 kHz Squelch Mid Filters Output amplitude 7 dBm Tone Key switch ON Low Pass 30 kHz ON Modulation See Table 2 High Pass 400 Hz ON Frequency Oper Freq minus 10 7 MHz 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 Z...

Страница 23: ...k 5 0 dB 4 0 dB 3 0 dB Audio freq response 10 Hz wrt 1 k 8 0 dB 9 0 dB 10 0 dB UA System S N 45 kHz A weighted 95 0 dB 100 0 dB Output power UA without C347 14 0 dBm 16 0 dBm 17 0 dBm MB MC System S N 1 THD A weighted 80 0 dB 85 0 dB Output power without C347 14 0 dBm 16 0 dBm 17 0 dBm KK System S N 1 THD A weighted 80 0 dB 85 0 dB Output power without C347 12 0 dBm 14 0 dBm 15 0 dBm JA JB System ...

Страница 24: ...Shure UC2 Hand Held UHF Transmitter 24 Notes 25A1044 RI Notes This page intentionally left blank ...

Страница 25: ...l operation n Battery voltage appears at TP 9 U311 pin 6 Check for reversed polarity capacitors C308 and C309 Check for open coil L300 Rf Problems n If the carrier is out of specification by less than 40 kHz and can not be corrected by adjusting C314 put the transmitter on the operating frequency see Table 2 Measure and adjust the dc voltage at TP30 See Table 2 for frequency variations If the carr...

Страница 26: ... the power out of the VCO is still low the problem is in the VCO n Check the values of R322 R323 R324 R325 and C329 n Isolate components starting from the antenna and working back to the rf power amp n Check the values continuity of the input and output matching net works for Q302 Q304 C329 C338 L305 C339 C340 L307 n Check the values of the bypass capacitors C357 C2 C332 C333 C334 C335 C360 C341 C...

Страница 27: ...low check the line for a short to 5 V If there is no short the micro processor is defective and must be replaced n If there is a 32 kHz signal at both I209 and TPA6 replace R236 n If there is not a 32 kHz signal at either I209 or TPA6 there is something wrong with the tone key circuit or the tone key supply voltage If the tone key supply voltage U200 pin 8 is less than 2 V there is a problem with ...

Страница 28: ...Shure UC2 Hand Held UHF Transmitter 28 Notes 25A1044 RI Notes This page intentionally left blank ...

Страница 29: ...ons Printed Circuit Boards in order by frequency Country Code Country Designation Frequency Range UC2 Printed Circuit Board MC Netherlands 774 782 MHz 90MC8792J UA U S A and Canada 782 806 MHz 90UA8792J JA Japan 797 806 MHz 90JA8792J MB Europe 800 830 MHz 90MB8792J JB Japan 806 810 MHz 90JB8792J KK United Kingdom 838 862 MHz 90KK8792J Table 4 Replacement Parts Reference Designation Description Shu...

Страница 30: ...r 100 nH 162A25 L502 Inductor 10 nH 162N25 Q3 201 211 212 213 Transistor SMD SOT 23 FET TMOS 183A30 Q202 Transistor chopper PNP SOT 23 183A07 Q203 303 305 Transistor SMD power MOSFET 183A46 Q204 208 209 210 220 Transistor SOT 23 NPN 183A02 Q301 Transistor 183A01 Q302 501 502 Transistor 183A48 R207 Potentiometer Gain 46H8014 R320 Potentiometer Trim 1 k 146B02 S200 Switch slide DPDT 55A178 S301 Swit...

Страница 31: ...nge 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 0 797 806 Japan JA 1 0 800 830 Europe MB 1 0 806 810 Japan JB 1 0 838 862 England KK 1 0 Country Code R28 Ω R29 Ω R30 kΩ R31 kΩ R32 kΩ R33 kΩ R34 kΩ R35 kΩ R36 Ω R37 Ω MC 1 0 UA 1 0 JA 1 0 MB 1 0 JB 1 0 KK 1 0 ...

Страница 32: ...12 JA 4 7 4 7 4 7 1 0 95A8278 183A01 183A02 249 10 0 MB 4 7 4 7 4 7 1 0 183A01 183A02 249 10 0 JB 4 7 4 7 4 7 1 0 95A8278 162A12 KK 3 9 2 2 3 9 183A01 183A02 249 10 0 Country Code R3 kΩ R6 kΩ R7 kΩ R8 kΩ R9 kΩ R10 MΩ R11 kΩ R12 kΩ R13 MΩ R16 kΩ R40 kΩ MC 1 5 10 0 4 02 10 0 100 1 0 10 0 22 1 1 0 UA 0 0 JA 1 5 4 02 4 02 4 02 100 1 0 10 0 22 1 1 0 146B02 MB 1 5 10 0 4 02 10 0 100 1 0 10 0 22 1 1 0 JB...

Страница 33: ...Shure UC2 Hand Held UHF Transmitter Replacement Parts and Drawings 33 25A1044 RI UC2 Hand Held UHF Transmitter Printed Circuit Board Side 1 ...

Страница 34: ...Shure UC2 Hand Held UHF Transmitter 34 Replacement Parts and Drawings 25A1044 RI UC2 Hand Held UHF Transmitter Printed Circuit Board Side 2 ...

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