AKG WMS 40 Service Manual

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AKG WMS 40 Service Manual

Extracted text from AKG WMS 40 Service Manual (Ocr-read)

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WMS 40 a Harman international company Page 2 of 25 The complete WMS 40 system: The actual frequency is not differentiated by item number! WMS 40 HT/US -“ Set with US power supply: 7611X0001 WMS 40 HT/EU -“ Set with EU power supply: 7612X0001 WMS 40 HT/UK -“ Set with UK power supply: 7613X0001 WMS 40 PT/US -“ Set with US power supply: 7611X0002 WMS 40 PT/EU -“ Set with US power supply: 7612X0002 WMS 40 PT/UK -“ Set with US power supply: 7613X0002 WMS 40 PT/US/Aerobic -“ Set with C444 and US power supply: 7611X0003 WMS 40 PT/EU/Aerobic -“ Set with C444 and EU power supply: 7612X0003 HT 40, handheld transmitter only: 7600X0001 PT 40, bodypack transmitter only: 7600X0002 SR40/US, receiver only with US power supply: 7601X0003 SR40/EU, receiver only with EU power supply: 7602X0003 SR40/UK, receiver only with UK power supply: 7603X0003 General remarks This manual contains technical information on the system functions and design. Exploded views and lists of all available mechanic parts and electronic assemblies are added. Further a list of electronic components for one specific frequency for both handheld and bodypack transmitters and receiver is added for better technical understanding and trouble shooting. However we do not stock or sell electronic components contained in those electronic components lists. When ordering frequency depending boards please state part number plus required frequency. All measurement values are nominal if not otherwise specified. All data subject to change without prior notice . All rights reserved. The contents of this manual shall be used for service purposes only. Any use of the information given herewith by third parties without permission of the copyright owner is strictly forbidden! Β© 2000 by AKG Acoustics GmbH, A Harman International Company, A-1230 Wien, Austria. Contacts: Phone: +431 86654-1519 Fax: +431 86654-1514 e-mail: service@akg.com

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a Harman international company a Harman international company WMS 40 Page 3 of 24 Short description Transmitter HT40: Audio part: The dynamic unit (D880) is connected via L1-L2-C6-C7 (RF-filter), to the MICAMP stage. The MICAMP is built as an amplifier, which is a part of the NE575- integrated circuit and has a gain of 8.8dB. It also forms the LOCUT filter at 30 Hz. Then the signal is fed to the COMP ressor. Here the dynamic of the amplitude is reduced to its half value, expressed in dB. This compressor is built with the integrated circuit NE575 from Signetics. In the feedback loop of the amplifier (Pin 12 and 14) there is the variable gain cell inserted. The variable gain cell is controlled by the rectified output voltage of the amplifier. C60 smoothes the rectified signal an controls the variable gain cell. C60 defines the so called time constant of the compressor. This feedback loop leads in an compression of the input signal. R7-R8-C10 build the DC path in the feedback loop. The second amplifier is used to build the PREEM phasis circuit, which boosts the higher frequencies with an time constant of 50usec and a fixed gain of 7.9dB at the lower frequencies. The DEV iation AD justment is realized with the potentiometer R16. Here at an input level of 100mV/1kHz the deviation is adjusted to 15kHz, which is the nominal modulation. Also at MUTE-position of the main switch, the signal is here shorted. Q2 with the additional parts form the HICUT filter at app. 25 kHz/3rd order. Via C29-R28-C30-R30 the signal modulates the CCO. RF part: The UHF Signal is generated by a crystal controlled oscillator CCO and multiplier amplifier stages (AMP1 , AMP2 , AMP3 , AMP4 ). The third harmonic of the CCO is filtered by BPF1 , after 3 doubler stages Ftransmit/2 is filtered by BPF2 . After the output amplifier AMP5 the signal is filtered by LPF and a ceramic filter BPF3 . SETCode Transmitter Frequency Crystall Frequency Color US54 710,400MHz 14,800MHz reddish brown US58 734,600MHz 15,304MHz purple EU62 802,525MHz 16,719MHz warm red EU63 812,800MHz 16,933MHz yellow UK69A 854,900MHz 17,810MHz violet UK69B 858,200MHz 17,879MHz green ISM1 863,100MHz 17,981MHz melon yellow ISM2 864,375MHz 18,008MHz cool gray SP1 848,750 MHz 17,6822 MHz skyblue SP2 851,750 MHz 17,7447 MHz yellow green KR3 745,650 MHz 15,5344 MHz mintgreen KR4 750,900 MHz 15,6438 MHz dark grey Power supply: The internal voltage of 3.9V is generated from 2 AA size batteries with a DC/DC converter.