Bin And Jam Sensors - Ricoh FT7770 Service Manual

3. Bin and Jam Sensors

bin copy sensors (upper and lower) detect copy paper in the bins. The
The
jam sensors (upper and lower) check that copy paper is fed to the bins and
also count copies as they enter the bins.
The circuit description for all four sensors is the same (except for
connector numbers and pin numbers). So, we will discuss only the upper bin
copy sensor circuit (shown above).
When there is no paper in the sorter bins, LED-270 on the sensor LED
board activates PH1.
greater than pin 11.
lower than pin 11, causing pin 13 of IC201 to output HIGH.
IC202 is then higher than pin 10; so, IC202 pin 13 goes HIGH. This HIGH
signal at CN112-A8 informs the sorter main board that no paper is present.
When paper enters a bin, the phototransistor (PH1) turns off. This causes
the circuit to output a LOW signal to CN112-A8. The sorter main board
determines that paper is in the bins.
PH1 turns on Q254, which causes IC203 pin 10 to be
IC203 pin 13 then goes LOW. IC201 pin 10 is then
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Pin 11 of