R305MR
9 – 1
R305MR
Service Manual
CHAPTER 9.
TOUCH CONTROL PANEL ASSEMBLY
[1] OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
1) Key Unit
2) Control Unit (The Control Unit consists of Power Unit and CPU
Unit).
The principal functions of these units and the signals communicated
among them are explained below.
1. Key Unit
The key unit is composed of a matrix, signals generated in the LSI are
sent to the key unit through P46 and P51—P57. When a key pad is
touched, a signal is completed through the key unit and passed back
to the LSI through AN2—AN5 to perform the function that was
requested.
2. 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 14 segments and 3 common electrodes
using a Liquid Crystal 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 avail-
able in order to compose a basic standard time in the clock circuit.
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 com-
pose 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)
Back Light Circuit
A circuit to drive the back light (Light emitting diodes LD1- LD3).
Symbol
Voltage
Application
VSS
-5V
LSI(IC1)
