Touch Control Panel Assembly - Frigidaire FMV157GS Service Manual

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The touch control section consists of the following units
as shown in the touch control panel circuit.
(1) Key Unit
(2) Control Unit (The Control unit consists of LSI Unit and
Power U nit)
The principal functions of these units and the signals com-
municated 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 P20, P21, P22,
P25, and P26.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P43, P44,
P45 and P46 to perform the function that was requested.
Control Unit
Control unit consists of LSI, power source circuit, synchro-
nizing signal circuit, reset circuit, buzzer circuit, relay circuit
indicator 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.
LSI
The I/O signal of the LSI is detailed in the following table.
Pin No. Signal
1-2 VL2-VL1
3-6 AN7-AN4

TOUCH CONTROL PANEL ASSEMBLY

OUTLINE OF TOUCH CONTROL PANEL
DESCRIPTION OF LSI
I/O
IN Power source voltage input terminal.
Standard voltage for LCD.
IN Terminal to change cooking input according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the Model
in operation is applied to set up its cooking constant.
Symbol Voltage
VC -5.3V
3) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock cir-
cuit. It incorporates a very small error because it works
on commercial frequency.
4) Reset Circuit
A circuit to generate a signals which resetting the LSI to
the initial state when power is applied.
5) Buzzer Circuit
The buzzer is responds to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6) Door Sensing Switch
A switch to inform the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, fan motor, turntable motor, hood
motor, and light the oven lamp and hood lamp.
8) Indicator Circuit
This circuit consists of 22 segments and 3 common
electrodes using a Light Crystal Display.
9) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD1-LD4).
Description
Page 26
FMV157GC
Application
LSI(IC1)