R220KW
9 – 1
R220KW
Service Manual
CHAPTER 9.
TOUCH CONTROL PANEL ASSEMBLY
[1] OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units as shown in
the touch control panel circuit.
(1) Key Unit (2) Control 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 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 and synchronizing signal cir-
cuit.
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 4-digits, 12-segments and 3-common elec-
trodes 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 compose a basic standard time in the clock circuit.
4) Relay 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.
[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 G7 line on key matrix is touched, a corresponding signal out of P24 - 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 G8 line on key matrix is touched, a corresponding signal will be input into P51.
3
P52
IN
Signal similar to P50.
When either G9 line on key matrix is touched, a corresponding signal will be input into P52.
4
P53
IN
Signal similar to P50.
When either G10 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
Terminal not used.
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 COM0.
23
COM1
OUT
Common data signal.
Connected to LCD signal COM1.
