10-6) Key Scan And Display Circuit - Samsung RS257BABB Service Manual

Circuit Descriptions
10-6) Display Circuit
The panel exchanges data through communication between Main PCB and Panel PCB.
With the initial power on,Panel PCB gets information (temperature and settings)from Main PCB and displays
it. At this time, it blinks at an interval of 0.5 sec On and 0.5 sec Off if there is communication problem
between Main PCB and Panel PCB. The blinking continues until they communicate each other normally.
And, when they communicate each other normally, it stops blinking immediately and displays normally. As
shown in the figure, the panel picks up the Ambient Sensor and sends the information to Main PCB, and
Main PCB directly picks up the Ice S/W. The Panel LCD Backlight lights up when there is an input signal
such as Door Open or Button Input and the Backlight grows dim automatically, which is a power saving
feature.
1) Key Scan and display operation.
Note)
1) F-DEF-sensor and Bimetal work in parallel.
2) At the first power on, an open error (5V input to
MICOM) can be detected by self-diagnostics. A
short error will be ignored.
3) In self-diagnostics during a normal operation, only
an open error can be detected.
4) The F-DEF heater will be off at the set temperature
after the bimetal is off.
The model uses a decorder IC which 4 inputs and 9 outputs.
If the IC 9 decorder (TC4028BP) receivesd signals from
MICOM pins (3�6), an output signal per 2 miliseconds
comes out from Q3, Q41, Q8, Q6, Q9, Q7, Q0, Q2, and Q4
pin in sequence. This signal enters to a driver IC input
terminal of the CoolSelect Zone
62783AP), then approximate 11V peaks will generate from
an output terminal as shown on the next page.
40
TM PCB and IC5 (TD