Shure U4D Dual Diversity UHF Receiver
17 25D1062 (AG)Service Procedures
Service Procedures
Product Changes
The following changes have been made to the U4D receiver.
New Volume Control Knobs and Potentiometers
The new potentiometers cannot be used on old boards, and the new
knob assembly cannot be used with old potentiometers.
PRINTED CIRCUIT
BOARD REVISION
R110 VOLUME CONTROL
POTENTIOMETER PART NO.
VOLUME CONTROL KNOB
ASSEMBLY PART NO.
“G” or earlier 46A8048 90A8652
“H” or later 46A8069 90A8747
New Digital Display Board Pushbutton Actuators
The old actuators cannot be used on newer display boards. If for
any reason the display board is replaced, the actuators must also be
updated. However, any revision display board can be mixed with any
revision rf–audio board. On newer boards, the switches will be surface
mount components; on older boards the switches are thru-hole
components.
PRINTED CIRCUIT
BOARD REVISION
RUBBER ACTUATOR
PART NO.
PUSHBUTTON SWITCH
PART NO.
“J” or earlier 66A8039 55A187 (thru-hole)
“K” or later 66A8044, 66A8045 155A03 (SMT)
New PCB layout, component changes and designations
The U4 receiver PCB layout (34A8507K and earlier) has been
revised due to discontinued status to part number 188A190 (FM IF/Quad
detector). The new replacement component 188A129 (FM IF/Quad
detector) is not pin for pin compatible so, associated support circuitry
was added which results in the new PCB layout (34A8703). Also a new
choice of RF front end filters were chosen which contributed to the new
PCB layout change
PRINTED CIRCUIT
BOARD REVISION
FM IF / QUAD
DETECTOR
QUADRATURE
COIL
34A8507K or earlier U303 and U313 L304 and L310
34A8703 U315 and U316 FL311 and FL313
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