18
R-2277
R-2287
The control section consists of the following units as
shown in the touch control panel circuit.
(1) Control Unit
(2) Key Unit
The principal functions of these units and the signals
communicated among them are explained below.
1. Control Unit
Signal of key touch and oven function control are all
processed by one microcomputer.
1) Power Supply Circuit
This circuit changes output voltage at the secondary
side of the low voltage (T1) transformer to volatges
required at each part by full wave rectifying circuit,
constant voltage circuit, etc..
2) ACL Circuit
This is an Auto-clear Circuit, i.e., a reset circuit, which
enables IC1 to be activated from initial state.
3) Power SYNC Signal Generating Circuit
This is a circuit for generating power SYNC signal by
virtue of the secondary side output of transformer T1.
This signal is used for a basic frequency to time
processing and so on.
4) Clock Circuit
This is a circuit for controlling clock frequency required
for operating IC1.
5) IC1 (Main Processor)
This is a one-chip microcomputer, responsible for
controlling the entire control unit.
6) Display Circuit
This is a circuit for driving display tubes by IC1 output.
7) Switch Input Circuit
This is a circuit for transmitting switch input informa-
tion to IC1.
8) Sound-body Driving Circuit
This is a circuit for driving sound body by IC1 output.
9) Relay Driving Circuit
This is a circuit for driving output relay by IC1 output.
10) Stop Switch Circuit
This is a circuit for driving IC1 to detect door opening/
closing.
11) Exhaust Air Temperature Detecting Circuit
This is a circuit for transmitting output change of
CONTROL PANEL ASSEMBLY
OUTLINE OF CONTROL PANEL
thermistor (Exhaust Air Temperature Sensor) to IC1.
12)
High Voltage Monitoring Circuit.
This circuit detects problems in the magnetron / high
voltage circuit by sensing a variation in the current
flowing through the primary winding of the high voltage
transformer.
During heating, the primary current of the high voltage
transformers also flows through the primary winding of
the current transformers CT1 and CT2. This causes a
current to be induced in the secondary windings of
CT1/CT2 and results in an AC voltage which is
determined by R30/R31.
This AC voltage is then half wave rectified by D30/D31
and smoothed (filtered) by C30/C31.
This AC voltage is the input to the AN3 and AN4 ports
of IC1, which determines if there is a magnetron / high
voltage problem.
HIGH VOLTAGE TRANSFORMER
HIGH VOLTAGE CIRCUIT
MAIN BODY SIDE
T/C SIDE
CT1 or CT2
RY2 or RY3
R30 or
R31
R65 or
R66
D30 or
D31
R32 or
R33
Vc
C30 or C31
IC1
AN3 or
AN4 PORT
D32 or
D33
Figure T-1. High Voltage Monitoring Circuit
13) Magnetron Temperature Detecting Circuit.
This is a circuit for transmitting output change of
thermistor (Magnetron Temperature Sensor) to IC1.
14) Intake Air Temperature Detecting Circuit.
This is a circuit for transmitting output change of
thermistor (Intake Air Sensor) to IC1.
2. Switch Unit
The switch unit is composed of a matrix circuit in which
when a switch it touched, one of signals P43 - P45
generated by the LSI, is passed through the switch
and returned to the LSI as one of signals P50 - P51.
3. Encoder
The encoder converts the signal generated by LSI into
the pulse signal, and the pulse signal is returned to the
LSI.
