Board Location; Circuit Description - Sony WLL-RX50 Maintenance Manual

1-5. Board Location

KY-540 board
KY-539 board

1-6. Circuit Description

1-6-1. MDM-11 Board
The MDM-11 board is mainly composed of the Receiving/
Demodulating block, TS SW block, system control block,
and power supply block.
Receiving/Demodulating Block
The Receiving/Demodulating block of this unit is com-
posed of the TUNER (TU1), LPF (FL101), AGC amplifier
(IC108), demodulator IC (IC109), and AFC IC (IC113) on
the MDM-11 board.
The TUNER (TU1) extracts the frequency set in the CPU
from the IF signal input at the IF INPUT connector, and
converts it into the signal with the center frequency of 4.5
MHz to output.
TUNER (TU1) also outputs the IF signal from the IF
INPUT connector to the IF OUTPUT connector through
the buffer in the TUNER (TU1).
The signal output from the TUNER (TU1) is input to the
AGC amplifier (IC108) through the LPF (FL101), and is
controlled in gain by the AGC error voltage from the
demodulator IC (IC109).
The signal output from the AGC amplifier (IC108) is
added the bias voltage (DC 1.1 V) for the A/D converter of
demodulator IC (IC109), and is input to the demodulator
IC (IC109).
The OFDM signal is demodulated to the TS signal by the
demodulator IC (IC109).
The AFC IC (IC113) controls the PLL of the clock using
the sync signal playbacked by the demodulator IC (IC109).
WLL-RX50
TS SW block
The TS signal output from the demodulator IC (IC109) is
input to the TS switching IC (IC460).
The TS signal input to the TS switching IC (IC460) is re-
MDM-11 board
arranged to the packet of 188 bytes, and is output to the
STREAM OUTPUT connector.
When the diversity reception system is used, this signal is
compared to the signal(s) input to the TS switching IC
(IC460) from the STREAM EXT IN connector, and a
signal that is the most regularly received is selected and
output to the STREAM OUTPUT connector.
System Control Block
The HOST CPU (IC503) on the MDM-11 board performs
the system control of the unit.
The program in the HOST CPU (IC503) is downloaded
using the CN502 on the MDM-11 board.
Power Supply Block
The power supply block of this unit functions properly
with the power of +10.5 V to +17 V. It also supplies the
power to the down-converter from the IF INPUT connec-
tor.
The power is supplied from the AC IN connector (switch-
ing regulator) or the DC IN connector. Either of them is
selected in the relay (RY1001). Generally the AC IN
connector is selected.
The power from the relay (RY1001) is sent to the five
types of voltages (+10 V, +5 V, +3.3 V, +2.5 V, and
_6 V.) through the DC/DC converter ICs (IC1002 to
IC1004).
The power supply block has the following functions:
. Generates the regulated voltage and prevents from the
over/under voltage.
. Detects the shortage of battery with the battery alarm.
(10.7 to 11.0 V)
. Powers off against the over voltage.
. Displays the voltage of AC or DC IN connecter on the
LCD.
1-6-2. KY-539 Board, KY-540 Board
The KY-539 Board contains the switches for the MENU
operation, and the KY-540 Board contains the LED for the
operation panel. They are connected to the HOST CPU
(IC503) for the system control on the MDM-11 Board.
1-3 (E)