R-204(W)
15
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, ACL circuit, buzzer circuit, encoder
circuit, indicator circuit and potentiometer circuit.
1) LSI
This LSI controls the encoder signal, tact switch strobe
signal, relay driving signal for oven function, buzzer
signal and LED signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control
unit.
Symbol
Voltage
Application
VC
-5.0V
LSI(I-1)
3) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit. It accompanies a very small error because it
works on commercial frequency.
4) ACL
A circuit to generate a signals which resets the LSI to
the initial state when power is supplied.
CONTROL PANEL ASSEMBLY
OUTLINE OF CONTROL PANEL
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (tact switch touch sound and comple-
tion sound).
6) 2nd. Interlock Relay Control Switch
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, turntable motor and
light the oven lamp.
8) Encoder
The encoder generates the pulse signal, and the pulse
signal is sent to the LSI.
9) Indicator Circuit
Indicator elements are the Light-emitting diodes (LD1-
LD24).
This circuit consists of 4-digits and 6 segments.
10) Potentiometer Circuit
The circuit makes setting of the power level by variable
resistance.
DESCRIPTION OF LSI
LSI
The I/O signal of the LSI are detailed in the following table.
Pin No.
Signal
I/O
Description
1
VDD
IN
Power source voltage: 0V.
Connected to 0V.
2
VSS
IN
Power source voltage: -5V.
Connected to -5V.
3
XIN
IN
Internal clock oscillation frequency input setting.
The internal clock frequency is generated by connecting the capacitor and resistor
to XIN.
4
XOUT
OUT
Terminal not used.
5
CNVSS
IN
Connected to VSS through resistor R5.
6
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied.
7
P21
IN
Signal to synchronize LSI with commercial power source frequency.
This is basic timing for all real time
processing of LSI.
20 msec
H : GND
L : -5V
