8
R-21JCA
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, reset circuit, buzzer circuit, encoder
circuit and indicator circuit.
1) LSI
This LSI controls the encoder 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
+5V (*)
LSI(I-1)
VR
+20V (*)
RELAY(RY1, RY2)
(*) The voltage under the condition when all LEDs light
up. The voltage VR will vary according to the quantity
of the LEDs which light up.
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.
CONTROL PANEL ASSEMBLY
OUTLINE OF CONTROL PANEL
4) Reset Circuit
A circuit to generate a signals which resets the LSI to the
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (completion sound).
6) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, antenna 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-
LD20).
This circuit consists of 4-digits and 5 segments.
DESCRIPTION OF LSI
LSI (IXA167DR)
The I/O signal of the LSI (IXA167DR) are detailed in the following table.
Pin No.
Signal
I/O
Description
1
D3
OUT
Segment data signal.
Signal is input to the cathodes of the light-emitting diodes (LD1, LD6, LD11 and LD16).
2
D4
OUT
Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD16 - LD20).
3
D5
OUT
Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD11 - LD15).
4
D6
OUT
Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD6 - LD10).
5
D7
OUT
Digit selection signal.
Signal is input to the anodes of the light-emitting diodes (LD1 - LD5).
6
P20
IN
Connected to VDD terminal.
7
P21
IN
Connected to VSS terminal.
8
P22
IN
Signal coming from encoder.
When the encoder is turned, the contacts of encoder make pulse signals. And
pulse signals are input into P22.
Summary of Contents for R21JCA - Commercial Microwave Oven
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