Panasonic KX-FT931LA-B Service Manual page 29

6.5.5. Document Top Sensor (SW39)
When a document is brought to the read position, the SW becomes ON, and the input signal of IC1-5 pin (Operation) becomes a
low level. When there is no document at the read position, the SW becomes OFF, and the input signal of IC1-5 pin (Operation)
becomes a high level.
6.5.6. Document Set Sensor (SW38)
When a document is set, the SW becomes ON, and input signal of IC1-6 pin (Operation) becomes a low level.
When there is no document, the SW becomes OFF, and the input signal of IC1-6 pin (Operation) becomes a high level.
Operation Board
Out of the Read Position
At the Read Position
Operation Board
No document
Set document
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Signal (IC1-5 pin)
High level
Low level
Signal (IC1-6 pin)
High level
Low level
KX-FT931LA-B