R308KW
9 – 1
R308KW
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 CPU
Unit).
The principal functions of these units and the signals communicated
among them 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 P22, P23, P24, P25, P26, P31, P32 and
P33. When a key pad is touched, a signal is completed through the
key unit and passed back to the LSI through P50, P51, P52 and P53 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 14 segments and 3 common electrodes
using a Liquid Crystal Display.
3)
Power Source Circuit
This circuit generates voltages necessary in the control unit from
the AC line voltage. In addition, the synchronizing signal is avail-
able in order to compose 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- LD3).
[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
P50
IN
Signal coming from touch key.
When either G9 line on key matrix is touched, a corresponding signal out of P22 - P26 and P31 - P33 will be
input into P50. When no key is touched, the signal is held at “H” level.
2
P51
IN
Signal similar to P50.
When either G10 line on key matrix is touched, a corresponding signal will be input into P51.
3
P52
IN
Signal similar to P50.
When either G11 line on key matrix is touched, a corresponding signal will be input into P52.
4
P53
IN
Signal similar to P50.
When either G12 line on key matrix is touched, a corresponding signal will be input into P53.
5
IC
IN
Connected to VSS.
6
XT1
IN
Connected to VSS.
7
XT2
-
Terminal not used.
8
VDD
IN
Power source voltage input terminal.
The power source voltage to drive the LSI. Connected to GND.
9
VSS
IN
Power source voltage input terminal.
The power source voltage to drive the LSI.
10
X1
IN
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the resistor-capacitor oscillation circuit with respect to X2 termi-
nal.
11
X2
OUT
Internal clock oscillation frequency control output.
Output to control oscillation input of X1.
12
RESET
IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied.
13-15
P00-P02
OUT Terminal not used.
16
P03
OUT Back light circuit (Light emitting diodes) driving signal.
17
CAPH
-
Terminal not used.
18
CAPL
-
Terminal not used.
19-21
VLC0-VLC2
IN
Power source voltage input terminal.
Standard voltage for LCD.
22
COM0
OUT
Common data signal.
Connected to LCD signal COM1.
