Sony DWT-B30, Service Manual

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7-1 (E)
DWT-B30
7-1. Circuit Description
This unit consists of the following boards.
.
TX-172 board
.
DPR-396 board
.
RM-215 board
.
LED-498 board
.
CN-4088 board
.
CN-4078 board (for H (CE) and L (CE) destinations) or CN-4148 board (for CN, UC, G (J), and MH (J)
destinations)
7-1-1. TX-172 Board
The TX-172 board mounts the circuits below.
.
Power circuit
.
Audio circuit in the range of the head amplifier to the A/D converter
.
PLL circuit that oscillates and controls the carrier in the bandwidth of 470 MHz to 810 MHz and 1240
MHz to 1260 MHz
.
Orthogonal modulation circuit (that modulates an IQ signal using the carrier generated by the PLL
circuit)
.
High-frequency amplifier circuit
Power circuit (A part of reference Nos. 600 to 699 and 700 to 799)
.
IC600 and IC601 are the step-up/down DC-DC converter.
.
IC600 generates
+
5.2 V. It is mainly used in the audio circuit and RF circuit.
.
IC601 generates
+
3.1 V. It is mainly used in the audio circuit or RF circuit and digital circuit.
.
The IC605’s peripheral circuit detects the remaining amount of a battery. When the voltage of the
battery becomes less than about 1.7 V, it forcibly turns off IC609 (separates the battery from a circuit) to
prevent the battery from liquid leakage.
Audio circuit (Reference Nos. 500 to 599)
.
The head amplifier circuit consists of IC500 and IC504.
.
The gain of the head amplifier is changed by switching the internal switch of IC500.
The attenuator in the input stage is turned on and off by controlling PH501 to PH503.
.
The audio signal amplified using the head amplifier is converted from analog to digital using IC570.
.
Up to the input block of IC570 is treated as the analog audio circuit.
PLL circuit (IC808’s peripheral circuit)
IC808 receives frequency setting data from CPU (IC402 on the DPR-396 board) and controls the oscilla-
tion frequency of a carrier, which VCO802 outputs, with the oscillation frequency of X801 as standard.
Orthogonal modulation circuit (IC802’s peripheral circuit)
IC802 modulates the I/Q signal, input from FPGA, to the carrier input from VCO802.
Section 7
Diagrams