Wolf MWD24-2 Service Manual page 29

Drawer Microwave
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL:
The touch control section consists of the following units.
• Key Unit
• Control Unit
• Power 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 from P0 - P7. When a
key pad is touched, a signal is completed through the key unit and passed back to the LSI through P20 - P23 to per-
form the function that was requested.
CONTROL UNIT AND POWER UNIT:
Control Unit: Consists of LSI, IC, reset circuit, indicator circuit, power source circuit, relay circuit, buzzer circuit,
synchro-nizing signal circuit, keyboard unit circuit, humidity sensor circuit and back light circuit.
1. IC1 (LSI): This is a microcomputer, responsible for controlling the entire control unit.
2. IC2: This is the IC to drive the Liquid Crystal Display.
3. IC5: This is the IC to amplify the signal from the humidity sensor.
4. Reset Circuit: This circuit generates a signal which resets the LSI (IC) to the initial state when power is supplied.
5. Indicator Circuit: A circuit to drive the Liquid Crystal Displays (LCD).
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
VC +5V LSI(IC)
Relay Circuit : A circuit to drive the magnetron, fan motor, stirrer motor and light the oven lamp.
Buzzer Circuit: The buzzer is responsive to signals from the LSI to emit audible sounds (key touch sound and com-
pletion sound).
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.
Door Sensing Switch (Microwave Drawer): A switch to "tell" the LSI if the drawer is open or closed.
Door Position Switch Front / Rear: The switch to "tell" the position of the Microwave drawer door.
Back Light Circuit: A circuit to drive the back light (Light emitting diodes LD- LD3).
Humidity Sensor Circuit: This circuit detects moisture of the cooking food to allow its automatic cooking.
Microwave Drawer Door Open-Close Circuit: A circuit to drive the microwave drawer door open-close motor.
(Models MWD24-2 / MWD30-2)
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Theory of Operation
#813632 - Revision B - December, 2009