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R-25JT-F

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL

The touch control section consists of the following units as
shown in the touch control panel circuit.

(1) Control Unit
(2) Key Unit

The principal functions of these units and the signals commu-
nicated among them are explained below.

1. Control Unit

Signal of key touch and oven function control are all
processed by one microcomputer.

1) Power Supply Circuit

This circuit changes output voltage at the secondary side
of the low voltage (T1) transformer to voltages required at
each part by full wave rectifying circuit, constant voltage
circuit, etc..

2) ACL Circuit

This is an Auto-clear Circuit, i.e., a reset circuit, which
enables IC1 to be activated from initial state.

3) Power Synchronizing Signal Generating Circuit

This is a circuit for generating power synchronizing signal
by virtue of the secondary side output of transformer T1.
This signal is used as a basic frequency for time process-
ing.

4) Clock Circuit

This is a circuit for controlling clock frequency required for
operating IC1.

5) IC1 (Main Processor)

This is a one-chip microcomputer, responsible for control-
ling the entire control unit.

6) IC2 (Memory Processor)

This is a memory IC, responsible for memory function.

7) IC3

This is a IC for driving light emitting diode.

8) Display Circuit

This is a circuit for driving light emitting diode by IC1 output.

9) Key Input Circuit

This is a circuit for transmitting key input information to IC1.

10) Sound-body Driving Circuit

This is a circuit for driving sound body by IC1 output.

11) Relay Driving Circuit

This is a circuit for driving output relay by IC1 output.

12) Door Sensing Switch Circuit

This is a circuit for driving IC1 to detect door opening/
closing.

13) Exhaust Air Temperature Detecting Circuit

This is a circuit for transmitting output change of thermistor
(Oven thermistor (1)) to IC1.

14) Magnetron Temperature Circuit

(Detect no load or fan lock)

This is a circuit for transmitting output change of thermistor
(Magnetron thermistor) to IC1.

17) Supply Voltage Detecting Circuit

This is a circuit for detecting troubles of input voltage at
microwave oven. The function of this circuit is to divide the
variation of voltage across C1 to supply voltage variation
by ZD1, R1 and R2 and to put the result to AN6 port of IC1
for detection.

FIgure T-2. Supply Voltage Detecting Circuit

16) High Voltage Monitoring Circuit.

This circuit detects problems in the magnetron / high
voltage circuit by sensing a variation in the current flowing
through the primary winding of the high voltage trans-
former.
During heating, the primary current of the high voltage
transformers also flows through the primary winding of the
current transformer CT1. This causes a current to be
induced in the secondary winding of CT1 and results in an
AC voltage which is determined by R100.
This AC voltage is then half wave rectified by D100 and
smoothed (filtered) by C100.
This AC voltage is the input to the AN3 port of IC1, which
determines if there is a magnetron / high voltage problem.

Figure T-1. High Voltage Monitoring Circuit

TB1

TB2

CT1

D100

R102

R100

C100

47µ

/10v

0.01µ

/16v