PG4 Wireless Reciever Service Manual 25A1104 PG4 WIRELESS RECEIVER PRODUCT DESCRIPTION The Shure Model PG4 is a dual conversion super heterodyne, predictive diversity, microprocessor-controlled UHF receiver, operating over the frequency range of 536 MHz to 865 MHz. Power is supplied to the receiver by external dc supply with country specific approvals. The PG series is Shure's most basic, lowest price tier, frequency agile wireless series.
DETAILED DESCRIPTION Front Panel 1 1 audio LED 2 ready LED 3 4 LED screen channel button 2 3 4 Indicates strength of incoming audio signal: green for normal, amber for strong, red for peak. Green light indicates system is ready for use. Back Panel 1 1 2 3 4 25A1104 (Rev.
CIRCUIT DESCRIPTION General block diagram description. The receiver consists of the following components: Image filters, predictive diversity circuitry, down-converter, first IF strip, SAW filter, second mixer, second IF strip, ceramic filter, detector, RSSI buffer, low pass filter, RMS detector and expander, mute circuit, balanced and unbalanced audio outputs, tonekey detection circuit, noise squelch circuit, microprocessor and several voltage regulators.
The first, the second VCO's and PLL The first VCO is a two-stage design composed of an oscillator stage and a buffer stage. Its frequency is controlled with the synthesizer chip IC1. The first stage (Q724) is a common emitter Colpitts oscillator. The air wound resonator L720 is coupled to the transistor with C723, and to the modulation varactor diode by C721. Inductor L720, capacitor C720, and trimmer CV720 form the resonant tank. Trimmer capacitor CV720 sets the VCO tuning voltage.
RF & AUDIO BLOCK DIAGRAM From st 1 Mixer 110 MHz SAW Filter 2nd MIXER Buffer 2nd IF/Detector 10.7 MHz 10.7 MHz ceramic filters Buffer and DC gain Sanyo LA8662V Audio output 2nd LO RSSI output VCO LPF RF – 1st and 2nd IF 2nd mixer and detector LMX2335 LTM PLL From µP Controller Audio Outputs Unbalanced Buffer Audio Proc Muting 18 kHz LPF Balanced Tone Key Detector To uP Noise Squelch Detector Buffer Audio & Muting Circuitry 25A1104 (Rev.
Digital Section The Freescale 8Kb FLASH microprocessor was chosen to maximize its benefits and to reduce system cost. The internal ADC converters are utilized to sample DC voltages to handle switching diversity, audio metering, audio muting, noise squelching, and tone-key detection. RF band detection uses four digital inputs. In addition, the Freescale microprocessor controls the 7-segment LED display and handles the user interface channel selection.
RF BAND RESISTORS Four resistors Ra, Rb, Rc, and Rd are responsible to start the microcontroller in a RF band. Table 2 shows the reference designators and how the voltages at the test points reflect the operating RF band. . Table 2 PG4 Reference Designators Rd Rc Rb Ra R316 R315 R314 R313 Table 3 shows the variant resistor installation options for each band. When a resistor is installed the microprocessor will read a logic low, otherwise it will read a logic high.. Table 3 25A1104 (Rev.
Microcontroller Netnames and Programming Testpoint List Pin Port Name Testpoint TP_RST 1 RESETn Reset 2 PTC0/TxD2 Seven Segment A 3 PTC1/RxD2 Seven Segment B 4 5 6 PTC2/SDA1 PTC3/SCL1 PTC4 Seven Segment C Seven Segment D Seven Segment E 7 PTC5 Seven Segment F 8 9 PTC6 PTC7 Seven Segment G NC 10 PTE0/TxD1 Select Button 11 12 13 14 PTE1/RxD1 IRQ PTE2/SS1n PTE3/MISO1 NC NC Ra Rb 15 16 17 18 19 20 21 22 PTE4/MOSI1 Rc PTE5/SPSCK1 Rd VSS1 EGND VSS2 EGND VDD +3.
PG4 RSSI Curve TP_RSSI Vdc 2.5 2 1.5 Series1 1 -2 0 -3 0 -4 0 -5 0 -6 0 -7 0 -8 0 -9 0 -1 20 -1 10 -1 00 0.5 RF Level The microprocessor reads the RSSI level from an ADC several times a second when the PG4 is unmuted, to predict if a switch is necessary to avoid an audible dropout. Thresholds were calculated from the above RSSI curve. 25A1104 (Rev.
NOTES 25A1104 (Rev.
FUNCTIONAL TEST GENERAL INFORMATION LOOKUP TABLE Band H7 K7 M7 M10 P11 Q11 R11 R12 R10 JB T10 Fc (MHz) Low High 536 548 590 602 662 674 674 686 702 714 740 752 770 782 794 806 800 812 806 810 854 865 1st Image Band (MHz) Low High 757.2 769.2 811.2 823.2 883.2 895.2 895.2 907.2 480.8 492.8 518.8 530.8 548.8 560.8 572.8 584.8 578.8 590.8 584.8 588.8 632.8 643.8 Local oscillators 1st LO 2nd LO Fc+110.6 99.9MHz Fc+110.6 99.9MHz Fc+110.6 99.9MHz Fc+110.6 99.9MHz Fc-110.6 121.3MHz Fc-110.6 121.3MHz Fc-110.
Deviation Q11 All other frequencies 27.5 kHz 37.5 kHz TONE KEY INDICATOR 1. Modulate the RF signal with 32.768 kHz tone key generator. (If using an HP E4400B RF Generator use the DualSine wave feature by pressing: more, FM Waveform (Sine), and Dual-Sine). Set the following: • FM Tone 2 Rate = 32.768kHz • FM Tone 2 Amplitude = (see table below) FM Tone 2 Amplitude 2. 3. Q11 All other frequencies 16% 12% Connect an antenna to the RF signal generator output.
ASSEMBLY AND DISASSEMBLY !CAUTION! Observe precautions when handling this static-sensitive device. ASSEMBLY INSTRUCTIONS (REVERSE FOR DISASSEMBLY) 1. 2. REF LOW BAND ANTENNA (MORE TRIANGULAR SHAPED) REF: ANTENNAS SHOWN SUPERIMPOSED TO SHOW DIFFERENT POSITIONS AND GEOMETRIES. ANTENNA SIDE CLIPS NOTE 6 REF HIGH BAND ANTENNA (MORE SQUARE SHAPED) 25A1104 (Rev.
3. REF HIGH BAND LEFT REF LOW BAND LEFT REF LOW BAND, RIGHT REF HIGH BAND, RIGHT 2-ISOMETRIC 25A1104 (Rev.
SERVICE PROCEDURES MEASUREMENT REFERENCE NOTE: Audio levels in dBu are marked as dBm on the HP8903. dB Conversion Chart 0dBV = 2.2 dBu 0dBu = 0dBm assuming the load = 600 ohms Be aware that dBu is a measure of voltage and dBm is a measure of power. The HP8903, for example, should be labeled dBu instead of dBm since it is a voltage measurement. These two terms are often used interchangeably even though they have different meanings.
ALIGNMENT AND MEASUREMENT PROCEDURE General notes The following procedures are intended for a "bench" testing environment only. The alignment procedure is sequential and does not change unless specified. Use an RG-178/U BNC male to unterminated cable for all RF connections to the antenna inputs. Keep the test cables as short as possible (less than 3 feet in length). Include the insertion loss of the cables and the connectors when performing all RF measurements. DC voltages may present at RF test points.
POWER TEST SECTION 1. 2. 3. 4. 5. 6. Measure +9.0 Vdc + 0.2 /-0.2 Vdc at test point "TP_9V" Measure +5.0 Vdc + 0.1 /-0.1 Vdc at test point "TP_5V" Measure +5.0 Vdc + 0.2 /-0.2 Vdc at test point "TP_5VPLL" Measure +3.3 Vdc + 0.2 /-0.2 Vdc at test point "TP3.3V" Measure +4.5 Vdc + 0.2 /-0.2 Vdc at test point "TP_VREF" The dc current drain should be 120 mA +/- 25 mA. 1ST LOCAL OSCILLATOR 1. 2. Adjust CV720 to set voltage at TP1 to +3.75 Vdc ± 0.1 Vdc. Attach a frequency counter to TP600.
4. 5. 6. Set signal generator level= -100 dBm. Set signal generator to corresponding frequency. Measure SINAD at TPR (Pin 7 of IC610) to be equal to or greater than 12 dB. TONEKEY LEVEL DETECTION 1. 2. 3. Verify the receiver is set to ATE mode Fmid frequency. Set the RF generator's amplitude to -70dBm and carrier frequency to ATE Fmid frequency. Apply a dual-sine modulation function with FM rate1=1KHz and FM rate2=32.768KHz and ampl=12%. Set the deviation to 37.5KHz.
NOTES 25A1104 (Rev.
AGENCY APPROVALS FCC DD4 PG4 (Part 15 "Declaration of Conformity" filed) IC RSS-123 (Canada # 616A-PG4) Professional Only CE (Declaration of Conformity to latest version of ETSI EN 301-389) ADDITIONAL PRODUCT PERFORMANCE CHARACTERISTICS (NOT TESTED IN PRODUCTION): General notes: A-weighting filter, RF testing level = -70 dBm, 33kHz Deviation @ 1 kHz modulation frequency, unless otherwise specified. Audio & RF tests at the detector output: Audio level : 100 mV RMS min S/N Ratio: 50 dB min.
FREQUENCY TABLES Group A Group B N. & S. America N. & S. America H7 CH 1 2 3 4 5 6 7 8 9 0 536 - 548 Freq 536.075 547.925 537.275 546.725 540.025 543.975 541.925 542.075 547.175 536.825 K7 CH 1 2 3 4 5 6 7 8 9 0 590 - 602 Freq 590.075 601.925 591.275 600.725 594.025 597.975 595.925 596.075 601.175 590.825 Group C Group D Group E Group F N. & S. America Australia / France China China / Korea M7 CH 1 2 3 4 5 6 7 8 9 0 662-674 Freq 662.075 673.925 663.275 672.725 666.025 669.975 667.925 668.
PRODUCT SPECIFICATIONS System Working Range 75m (250 ft.) Note: actual range depends on RF signal absorption, reflection, and interference Audio Frequency Response +/– 2 dB Minimum: 45 Hz Maximum: 15 kHz (Overall system frequency depends on microphone element.) Total Harmonic Distortion 0.5%, typical Ref.
TROUBLESHOOTING Current draw and DC regulator tests 1. 2. 3. Connect the PS20 DC power supply to CON400. Verify current draw is 120mA +/- 25mA. If the current draw is above or below above specification disconnect the 9Vdc, 5Vdc and 3.3Vdc regulated power supply feed points to each section of the receiver to deductively troubleshoot which section is causing the excessive current drain. DC regulated Power supply voltages CHECK FOR 9.0VDC (±0.2 VDC) AT TP_9V (PIN 4 OF IC400): 1. 2. 3. 4. 5. 6.
under test can cause erratic and poor measurements. Verify using a spectrum analyzer that the frequency of operation under test has no interference down to -90dBm. ·Remove both CH. A & B internal antennas from CON500 & CON505. ·Set the receiver into ATE mode and to “2” (Fmid). This sets the receiver to the center operating frequency and set the amplitude to -50dBm. Conductively inject the output of the RF generator to the respective antenna input under test. For CH. A inject into TP4 and for CH.
emitter dc measurements are not correct replace Q603. If the voltages on Q603 were correct troubleshoot for correct component placement and values back through the SAW filter FL600. Verify pin 4 of IC610 (2nd LO input) measures the respective 2nd LO frequency at approximately -12dBm. If the 2nd LO amplitude is low check the values and correct placement of all components leading back through the circuit path to the collector of Q760. The approximate dc voltage measurements for Q760 are collector=4.
Fails/Weak Audio at TPBAL2/TPBAL3 1.) 2.) 3.) 4.) 5.) Confirm audio at TPE Confirm 4.5VDC at TP_Vref Confirm tone key in RF signal or R280 is shorted to disable TK Check and confirm values of C144, C150, R150, R153 Check other components in vicinity Fails Tone Key at TP_TK 1.) 2.) 3.) 4.) 5.) 25A1104 (Rev.1) Confirm 4.5VDC at IC232 pins 1,5, and 7. Check RF signal for 32.
NOTES 25A1104 (Rev.
REPLACEMENT PARTS PRODUCT CHANGES PARTS DESIGNATIONS The following comments apply to the parts list and the schematics: Resistors: Unless otherwise noted, all resistors are surface-mount 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.
PG4 HARDWARE REPLACEMENT PART R e f e re nc e D e s c r i p t io n D e s ig n a t o r A1 S hure P a rt N um be r P G4 R EC EIVER C A SE A SSEM B LY 95B 9138 M P1 SH IELD ,C OVER ,SM A LL,ST EEL,T IN N ED 53A 8602 M P2 F EN C E,SH IELD ,ST EEL,P LA T ED ,T IN 53C 8538 M P3 R o H S SC R EW,T H D -F R M ,H D ,P A N ,P H ,ST L,YWL 30A 1245B PG4 PCB REPLACEMENT COMPONENTS Reference Designator CON145 CON155 CON400 CON402 CON500 CON505 C121 C144 C228 C405 C406 C715 C775 C776 C145 C399 C150 C152 C504
PG4 FREQUENCY DEPENDENT PARTS** F requency H7 K7 M7 M 10 P 11 Q 11 R 10 R 11 R 12 JB T 10 C o de 25A1104 (Rev.1) C1 2.7 pf DNP DNP DNP DNP DNP DNP DNP DNP DNP C10 DNP DNP DNP DNP DNP DNP DNP DNP DNP 2.7 pf DNP DNP C11 DNP DNP DNP DNP DNP DNP DNP DNP DNP DNP 2.7 pf C2 DNP 2.7 pf DNP DNP DNP DNP DNP DNP DNP DNP DNP C3 DNP DNP 2.
UNPLACED COMPONENT LIST** C103 C114 C165 C346 C347 C520 C521 C600 C602 C611 C612 C622 CV703 FL610 IC360 L540 L545 Q168 R168 R280 R346 R347 R360 R400 R612 R613 R776 R790 SHLD2 Y347 NOTE: APPLIES TO ALL FREQUENCY CODES 25A1104 (Rev.
PCB LAYOUT +3.3V DGND VREF TPR TP RSSI - A2D TPN TP2 TP3 TP600 TP5V 5VPLU TP9V TP750 TPI 32 25A1104 (Rev.
25A1104 (Rev.
