Sharp AR-651 Service Handbook page 165

[E12] Bypass misfeeding (paper not reaching the registration sensor)
Open the bypass unit cover. Is there any paper in front of the registration sensor?
YES
Remove the paper.
NO
Is the registration sensor working?
(Perform the input check in the test mode: 03-[ENERGY SAVER]ON/[4]/[E])
NO
1. Check if the connector of the registration sensor is disconnected.
2. Check if the connector J341 on the LGC board is disconnected.
3. Check if the connector pins are disconnected and the harnesses are open-circuited.
4. Check if the conductor pattern on the LGC board is short- or open-circuited.
5. Replace the registration sensor.
6. Replace the LGC board.
YES
Is the bypass feed clutch working? (Perform the output check in the test mode: 03-204)
NO
1. Check if the connector of the bypass feed clutch is disconnected.
2. Check if the connector J327 on the LGC board is disconnected.
3. Check if the connector pins are disconnected and the harnesses are open-circuited.
4. Check if the conductor pattern on the LGC board is short- or open-circuited.
5. Replace the bypass feed clutch.
6. Replace the LGC board.
YES
Check the bypass feed roller and separation roller. Replace them if they are worn out.
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