M2 MC2125PALS Service Manual - page 41
Manual is about: SIDE-BY-SIDE
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42
Circuit Descriptions
9-6) Key Scan and Display Circuit
Power Freeze
Freezer Temp.
Ice Type
Power Cool
Fridge Temp.
Child Lock
1) Key Scan and display operation.
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 IC5 (TD
62783AP), then approximate 11V peaks will generate from
an output terminal as shown on the next page.