Sharp KB-3300JS Service Manual - Page 30

KB-3300JS KB-3300JK KB-3300JW TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units. (1) Keyboard unit (2) Control Unit (3) Power unit The principal functions of these units and the signals communicated among them are explained below. Keyboard unit The keyboard unit is composed of a matrix, signals generated in the LSI are sent to the keyboard unit . When a key pad is touched, a signal is completed through the keyboard unit and passed back to the LSI to perform 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, synchronizing 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 (LCD1). 3) IC3 This is the IC to drive the Liquid Crystal Display (LCD2). 4) IC4 This is the IC to judge the selected key. 5) IC5 This is the IC to amplify the signal from the humidity sensor. 6) IC6 This is memory IC. 7) IC7 This is the IC to drive the relays. 8) IC8 This is the IC to drive the relays. 9) Reset Circuit This circuit generates a signal which resets the LSI (IC1) to the initial state when power is supplied. 10) Indicator Circuit A circuit to drive the Liquid Crystal Displays (LCD1, LCD2). 11) 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(IC1) 12) Relay Circuit A circuit to drive the magnetron, fan motor, stirrer motor, door lock motor, bottom heater, top heater and light the oven lamp. 13) Buzzer Circuit The buzzer is responsive to signals from the LSI to emit audible sounds (key touch sound and completion sound). 14) 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. 15) Door Sensing Switch (Microwave drawer) A switch to "tell" the LSI if the drawer is open or closed. 16) Door Switch (Oven) A switch to "tell" the LSI if the oven door is open or closed. 17) Door Lock Monitor Switch (Oven) A switch to "tell" the LSI if the oven door is locked or not. 18) Back Light Circuit A circuit to drive the back light (Light emitting diodes LD1- LD6). 19) Humidity Sensor Circuit This circuit detects moisture of the cooking food to allow its automatic cooking. 20) Temperature Measurement Circuit : (OVEN THERMISTOR) The temperature in the oven cavity is sensed by the thermistor. The variation of resistance according to sensed temperature is detected by the temperature measurement circuit and the result applied to LSI. The LSI uses this information to control the relay and display units. 28