Control Panel Assembly - Electrolux MC1751E Service Manual

The touch control section consists of the following units as shown in the touch control panel circuit.
(1) Switch Unit
(2) Control Unit
(3) LED Unit
The principal functions of these units and the signals communicated among them are explained below.
Switch Unit
The switch unit is composed of a matrix, signals generated in the LSI are sent to the switch unit
through P22, P23 and P24.
When a switch button is touched, a signal is completed through the switch unit and passed back to the
LSI through P50 and P51 to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, relay circuit, back light circuit, synchronizing signal
circuit, reset circuit, buzzer circuit, and indicator circuit.
1) LSI
This LSI controls the tact switch strobe signal, relay driving signal, for oven function and
indicator signal.
2) Power Source Circuit
This circuit generates voltage necessary in the control unit.
Symbol
VC
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.
4) ACL 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 (tact switch touch sound
and completion sound).
6) Stop Switch
A switch to "tell" the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, turntable motor, light the oven lamp.
8) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-common electrodes using a Liquid Crystal
Display.
9) Encoder
The encoder converts the signal generated by LSI into the pulse signal, and the pulse signal is
returned to the LSI.
10) Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1 - LD3).
LED Unit
A circuit consisting of three light emitting diodes (LD1- LD3)which are driven by the control unit
and provide the backlight for the display.
SOI 01.05 FV

CONTROL PANEL ASSEMBLY

OUTLINE OF CONTROL PANEL
Voltage Application
-5.0V LSI(IC1)
22/33 599 36 78-06