Shure u4d service manual

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1999, Shure Incorporated Printed in U.S.A. 25D1062 (AG) Service Manual 25D1062 (AG) U4D Dual Diversity UHF Receiver General Characteristics The Shure Model U4D Dual Diversity UHF Receiver is a microprocessor con- trolled dual diversity receiver operating in the UHF frequency range. This product is intended for use in high-end installed sound, rental, and concert sound mar- kets. Different frequency variations are available in various countries. Controls and Connectors 5 15 14 18 13 1617 17 18 16 19 15 7 1 23 5689 1011 12 4 7 1 23 6 84 1. MENU Button 2. SELECT Button 3. RF Level Indicators 4. AUDIO Level Indicators 5. Programmable Display 6. + Button 7.-“ Button 8. Volume Control 9. Headphone Monitor Volume Control 10. Headphone Monitor Status11. Headphone Input Connector 12. POWER On/Off Switch 13. Power Input Connector 14. Power Output Connector 15. Antenna Input Connectors 16. HIGH Z (Unbalanced) Output Connector 17. Mic/Line Slide Switch 18.LOW Z (Balanced) Output Connector 19. Networking Interface Figure 1.U4D Receiver 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. Licensing: Operation may require a user license. Frequency or power-output modifications may violate this products approvals. Contact your countrys communications authorities.

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Shure U4D Dual Diversity UHF Receiver 2 25D1062 (AG) Circuit Description Circuit Description Power Section The receiver accepts power line voltage ranging from 85 Vac to 264 Vac. The receiver hardware uses the +5 Vdc, +12 Vdc and 12 Vdc volt- ages from the switching power supply. The switching power supply has 40 W overall output power capability, with maximum current capabilities of 4A at 5V, 2A at +12V, and .5A at -“12V. It also includes a fast-“acting 2.5A fuse. Up to four in-line rf amplifiers may be connected to the receiver, depending on system setup. The receiver provides dc power to the in- line amplifiers via the BNC antenna ports and RG58 cables. Maximum dc power supplied to each antenna port is limited by self-“resettable fuse. Rf Section The rf circuit description is limited to one rf strip (channel A) in receiver 1. The other rf strip (channel B) is virtually identical. The local oscillator (LO) section is common for both channels and is described separately. Receiver 2 is identical to receiver 1. The rf input signals are sent from the antenna ports to the receiver via cables with BNC and rf mini-“plug connectors. Antenna port A is con- nected to J302 of receiver 1. Antenna port B is connected to J302 of receiver 2. Connectors J302 on each receiver are the input of the rf power dividers. Each of these splits the rf power from the antenna between two receivers. The outputs of the power dividers are connected to the inputs of the opposite rf strips of the other receiver: J303 of receiver 1 to J304 of receiver 2; and J303 of receiver 2 to J304 of receiver 1. In addition, J306 on receiver 1 and J306 on receiver 2 have to be solder jumpered to provide connection from the outputs of the rf power dividers to channel A rf strips of both receivers. Rf Channel The rf signal is preselected to the appropriate frequency range with two dielectric filters. The first dielectric filter is located between the antenna port and the low noise amplifier (LNA). The second filter is located between the LNA block and mixer input. The front end down-“ converter integrated circuit contains the LNA block and the first mixer. The first conversion produces the first intermediate frequency (IF) signal at 50 MHz. The first if signal is amplified with the MMIC, band- limited with a SAW filter, then down-converted to the second IF frequen- cy (10.7 MHz) with a second down-converter. The second down-converter has an internal second local oscillator (LO) that oscillates at 60.7 MHz, using an external crystal. The second LO buffered output also provides the LO drive to channel B of the sec-