Touch Control Panel Assembly Outline; Key Unit; Control Unit - Frigidaire CGMV173KB Servicing

Touch Control Panel Assembly Outline

The touch control section consists of the following units.

(1) Key unit

(2) Control Unit

The principal functions of these units and the signals
communicated among them are explained below.
KEY UNIT
The key unit is composed of a matrix, signals generated
in the LSI are sent to the key unit through P40 - P47.
When a key pad is touched, a signal is completed
through the key unit and passed back to the LSI through
P20, P21, P22, P00 and P01 to perform the function that
was requested.
CONTROL UNIT
Control unit consists of LSI, power source circuit,
synchronizing signal circuit, reset circuit, buzzer circuit,
relay circuit indicator circuit, humidity sensor circuit and
back light circuit.
1. LSI
This LSI controls the key strobe signal, relay driving
signal for oven function and indicator signal.
2. Power Source Circuit
This circuit generates voltages necessary for 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
VC -5.0V
3. Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit. It incorporates a very small error because it
works on commercial frequency.
4. Reset Circuit
This circuit generates a signal which resets the LSI
to the initial state when power is supplied.
5. Buzzer Circuit
The buzzer responds to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6. Stop Switch (Door Sensing Switch)
A switch to inform the LSI if the door is open or
closed.
Application
LSI(IC1)
Section 2 Operation
7. Relay Circuit
To drive the magnetron, fan motor, turntable motor,
stirrer motor, hood motor, and light the oven lamp
and hood lamp.
8. Indicator Circuit
This circuit consists of 25 segments and 4 common
electrodes using a Light Crystal Display.
9. Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1-LD5).
10. Humidity Sensor Circuit
This circuit detects moisture of the cooking food to
allow its automatic cooking.
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