R402JWT
9 – 1
R402JWT
Service Manual
CHAPTER 9.
TOUCH CONTROL PANEL ASSEMBLY
[1] OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power Unit and LSI Unit).
The principal functions of these units and their related signals are
explained below.
1. Key Unit
The key unit is composed of a matrix, signals generated in the LSI are
sent to the key unit through P20-P27.
When a key pad is touched, a signal is completed through the key unit
and passed back to the LSI through P70, P71, P41 and P45 to perform
the function that was requested.
2. Control Unit
Control unit consists of LSI, reset circuit, indicator circuit, power
source circuit, relay circuit, buzzer circuit, synchronizing signal circuit
and back light circuit.
1) Reset Circuit
This circuit generates a signal which resets the LSI to the initial
state when power is supplied.
2) Indicator Circuit
This circuit consists of 17 segments and 4 common electrodes
using a Liquid Crystal Display.
3) Power Source Circuit
This circuit generates voltage necessary in the control unit from the
AC line voltage.
In addition, the synchronizing signal is available in order to com-
pose a basic standard time in the clock circuit.
4) Relay Circuit
A circuit to drive the magnetron, fan motor, turntable motor and light
the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit audible
sounds (key touch sound and completion sound).
6) Synchronizing Signal Circuit
The power source synchronizing signal is available in order to com-
pose a basic standard time in the clock circuit. It accompanies a
very small error because it works on commercial frequency.
7) Door Sensing Switch
A switch to “tell” the LSI if the door is open or closed.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1- LD4).
9) Night Light Circuit
A circuit to drive the light emitting diode (LD10).
[2] DESCRIPTION OF LSI
The I/O signal of the LSI are detailed in the following table.
Symbol
Voltage
Application
VSS
-5V
LSI(IC1)
Pin No.
Signal
I/O
Description
1-2
VL2-VL1
IN
Power source voltage input terminal.
Standard voltage for LCD.
3-6
AN7-AN4
IN
Terminal to change cooking input according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the Model in operation is
applied to set up its cooking constant.
7
AN3
IN
Terminal not used.
8
AN2
IN
To input signal which communicates the door open/close information to LSI.
Door close “H” level signal (0V). Door open “L” level signal (-5V)
9
AN1
IN
Terminal not used.
10
AN0
IN
Terminal not used.
11-13
P57-P55
OUT Terminal not used.
14
CNTR0
OUT
Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.
15
P53
OUT Terminal not used.
16
P52
OUT
Oven lamp, fan motor and turntable motor driving signal
To turn on and off shut off relay (RY1). The square wave-
form voltage is delivered to the RY1 driving circuit and
RY2 control circuit.
17
P51
OUT Terminal not used.
A
B
0.1 sec.
2.0 sec.
H : GND
L : -5V
H : GND
L : -5V
16.7 msec.
During cooking
H : GND
L : -5V
