Circuit Description - Kenwood PW-A series Service Manual

OVERVIEW OF PW-A
AC power input to the AC inlet of the CPU unit passes
through the units shown below and reaches the output
terminals.
CPU unit → Power supply unit E/6 → CPU unit → Power
transformer → Power supply unit D/6 → Power supply
unit C/6 → Amplifier unit → Power supply unit E/6 →
Output terminals
The CPU unit has an AC inlet.
AC inlet passes through a noise-reducing capacitor,
protection fuse, and input voltage selector switch, and
reaches the power supply unit E/6 provided with the
main switch. When the main switch is thrown, the AC
power returns to the CPU unit once and is input to the
power transformer. The AC power insulated by the
power transformer and transformed to the voltage,
which depends on the model, is rectified by the power
supply unit D/6, smoothed by the power supply unit C/6,
controlled to the set value by the amplifier unit, and is
output through the output terminals of the power supply
unit B/6.
The PW-A power supply unit has as many routes as the
number of ouputs following the power transformer.
In addition to these units, the PW-A power supply unit
consists of power supply unit A/6, display unit, and
CPU unit. The power supply unit A/6 generates power
for the internal circuits, the display unit serves as the
interface, and the CPU unit controls the power and
executes various functions.
The IF-40RS/GU/USB option provides the PW-A power
supply unit with remote control functions.
The YB option (factory option) is also available.
factory option provides the PW-A power supply unit
with quicker voltage descent when the output is off.
With the input unit is connected with the amplifier unit,
the YB option discharges electric charge from the
output capacitors and lowers the voltage quickly.
PANEL UNIT (X66-182)
(A number is a number of a block diagram)
1. Rotary encoder (S25) --
attached to a front panel. When it turns in the direction
of a clockwise rotation, COM is contacted in order of A
and B, and it is set to L level. If it is an opposite
direction, it will become the order of B and A.
--
2. LED driver (IC1) Driver, which makes voltage
display LED turns on.
3. Volt age display LED (ED 1-4, D1) -- 7 segment LED
that displays a voltage value. D1 is a minus.
4. LED driver (IC2) -- Driver, which makes the current
display LED, turn on.
5. Current display LED (ED 5-8, D2) -- 7 segment LED
which displays a current value. D2 is a minus.
6. LED driver (IC3) -- LED with a switch and Driver,
which makes LED turn on
7. LED with switch (S1-12, S15-18, S21, S22, and S24)
-- LED for a display of each function and the switch for
a setup. LED is turned on by the driver, a switch
constitutes a matrix and scan is carried out from CPU.
Therefore, the switch and LED are separated in circuit.
8. Tact switch (S13, 14, 19, 20, 23)

CIRCUIT DESCRIPTION

AC power input to the
This
Rotary encoder for a setup
--
Switch for an
each setup. The matrix is constituted with LED with
switch, and scan is carried out from CPU.
9. Light Emitting Diode (D3-11) -- LED for each display.
LED which displays the beam of output and setting
change. The beam of setting change makes a voltage
and current side turns on by the same signal. It is
driven by LED driver (IC3).
Details of a signal
CS* -- Data is taken in by putting in H pulse after a
serial data (16Bit) input.
DATA -- The Serial data input (16Bit)
CLK -- IC clock pulse which operates IC, the serial data
of DATA is taken in in the standup of this pulse.
POWER SUPPLY UNIT (X68-221)
Power supply unit X68-2210-xx is divided into six of A-
F, and each has another function. Moreover, PC boards
of PW16-5ADP differ for the circuit
different from other models, and PW16-5ADP becomes
X68-2300-xx.
(A number is a number of a block diagram)
X68-2210(2300)-xx A/6
The unit which makes the power supply for internal
circuits.
1. Rectification, flat and smooth circuit -- It rectifies
and carries out flat and smooth the power supply used
by the digital system used in a CPU unit.
The voltage after being flat and smooth is about DC9V.
--
2. Regulation circuit The output of the above 1 is
regulated to DC5V. The consumption current in a CPU
unit is about 350mA, when IF unit is connected, it is
about 450mA.
3. Rectification, flat and smooth circuit -- It rectifies
and carries out flat and smooth the power supply used
by CH1 and 2 side among the power supplies of the
analog system used in an amplifier unit. The voltage
after being flat and smooth is about DC±17V. In AQ,
the power supply system here is used for 4CH(s) for
±12V is regulated in an amplifier unit.
the same COM.
--
4. Regulation circuit The output of the above 3 is
regulated to DC±5V. Consumption current is about
200mA, respectively.
5. Rectification, flat and smooth circuit -- It rectifies
and carries out flat and smooth the power supply used
by CH3 and 4 side among the power supplies of the
analog system used in an amplifier unit. The voltage
after being flat and smooth
(modification 02 to 04 and 08, X68-2300-00 are no
used) ±12V is regulated in an amplifier unit.
--
6. Regulation circuit The output of the above 5 is
regulated to DC ±5V. Consumption current is about
200mA, respectively. (modification 02 to 04 and 08,
X68-2300-00 are no used)
--
7. Regulation circuit Power supply±12V used in the
circuit of 8 to 12 are made. For power consumption, -
12V are about 30 to 40mA.
8. Heat detection circuit -- The heat of an exhaust gas
is detected with the thermistor of TH101
9. OHA signal generating circuit -- If a fixed value with
PW-A
composition
about DC ±17V.
is
+12 is about 10mA.
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