Electrolux EI27MO45GSA, Technical & Service Manual

Page: 16 / 52

Operation
2-4
Touch Control Panel Assembly
The touch control section consists of the following units.
1. Key Unit
2. Control Unit (Consists of Power Unit and LSI Unit).
The principal functions of these units and the signals
communicated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals generated
in the LSI are sent to the key unit through P53 ~ P57 &
P80 ~ 87. When a key pad is touched, a signal is com-
pleted through the key unit and passed back to the LSI
through P53 ~ P57 to perform the requested function.
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 VFD (Vacuum Fluorescent
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 available in order to compose
a basic standard time in the clock circuit.
Symbol Voltage Application
VSS -5V LSI(IC1)
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 compose 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. Absolute Humidity Sensor Circuit
This circuit detects moisture of the cooking food to
allow its automatic cooking.
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to the Figure D-1. When the open
button is pushed, the open button pushes up the switch
lever, and then the switch lever pushes up the latch head.
The latch heads are moved
upward and released from latch hook. Now the door will
open.
Figure 2-5 . Door Open Mechanism
Component Descriptions
Door Sensing
Switch
Monitor Switch
Switch Lever
Third Door
Switch
Latch Heads
Door
Primary
Switch
PRIMARY SWITCH, THIRD DOOR SWITCH & DOOR
SENSING SWITCH
The primary switch and third door switch mounted
parallel to each other horizontally in the lower positions
of the latch hook, the door sensing switch is mounted
horizontally in the upper position of the latch hook. They
are activated by the latch head on the door. When the
door is opened, the switches interrupt the power to all
high voltage components, except the oven lamp. A cook
cycle cannot take place until the door is firmly closed
thereby activating all interlock switches. The secondary
interlock system consists of the door sensing switch and
the secondary interlock relay located on the control circuit
board.