16
R-120DB
R-120DK
R-120DR
R-120DW
The touch control section consists of the following circuits as
shown in the touch control panel circuit.
The principal functions of these circuits and their related
signals are explained below.
Tact Switch
Signals generated in the LSI are sent to the tact switches
through P10, P11, P12 and P13.
When a tact switch is touched, a signal is completed through
the tact switch and passed back to the LSI through AN4,
AN5 and AN6 to perform the function that was requested.
Control Unit
Control unit consists of LSI, ACL circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit and syn-
chronizing signal circuit.
1) ACL
This circuit generates a signal which resets the LSI to the
initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 4-digits, 12-segments and 3-
common electrodes using a Liquid Crystal Display.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
3) Power Source Circuit
This circuit generates voltage 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)
4) Relay 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 (tact switch touch sound and completion
sound).
6) 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.
7) Door Sensing Switch
A switch to "tell" the LSI if the door is open or closed.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
7) Follow the troubleshooting guide given below for repair.
STEPS
OCCURRENCE
CAUSE OR CORRECTION
The rated AC voltage is not present between
1
Pin No. 3 of the 2-pin connector (A) and the
Check supply voltage and oven power cord.
common terminal of the relay RY2.
2
The rated AC voltage is present at primary
Low voltage transformer or secondary circuit defective.
side of low voltage transformer.
Check and replace the control unit.
8) Disconnect the power supply cord and then remove outer case.
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
