Sharp R-890SLM Service Manual download pdf (Page 20)

R-890SLM

9 - 1

CHAPTER 9. CONTROL PANEL ASSEMBLY

[1] OUTLINE OF CONTROL PANEL

The control section consists of the following units as shown in

the control panel circuit.

(1) Jog Switch Unit

(2) Control Unit

The principal functions of these units and signals communicated

among them are explained below.

1. Jog Switch Unit

The jog switch unit is composed of a matrix, signals generated

in the LSI are sent to the jog switch unit from P42 – P45.

When a button is touched, a signal is completed through the jog

switch unit and passed back to the LSI through P00, P20, P21

and P22 to perform the function that was requested.

2. Control Unit

Control unit consists of LSI, power source circuit, synchronizing

signal circuit, reset circuit, buzzer circuit, indicator circuit,

encoder circuit, potentiometer circuit, temperature measurement

circuit and back light circuit.

1) LSI

This LSI controls the temperature measurement signal, 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 Voltage Application

VC -5.2V LSI(IC1)

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) Reset Circuit

A circuit to generate a signal 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, top and bottom heating element,

convection motor, fan motor, turntable motor, touch control

transformer and light the oven lamp.

8) Encoder

The encoder converts the signal generated by LSI into the

pulse signal, and the pulse signal is returned to the LSI.

9) Potentiometer Circuit

The circuit makes setting of the cooking mode by variable

resistance.

10) Back Light Circuit

A circuit to drive the back light (Light emitting diodes LD1 -

LD10).

11) Indicator Circuit

This circuit consists 7-digits, 27-segments and 4-common

electrodes using a Liquid Crystal Display.

12) 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.

Service_R-890SLM.indd 20 4/25/09 10:55:25 AM

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 46 47

Comments to this Manuals

No comments

Sharp R-890SLM Service Manual Page 20

Comments to this Manuals

Related products and manuals for Microwaves Sharp R-890SLM