Sharp AR-651 Service Handbook page 169

[E16] 4th cassette misfeeding (paper not reaching the 4th cassette feed sensor)
Open the feed cover. Is there any paper in front of the 4th cassette feed sensor?
YES
Remove the paper.
NO
Is the 4th cassette feed sensor working?
(Perform the input check in the test mode: 03-[ENERGY SAVER]OFF/[5]/[B])
NO
1. Check if the connector of the 4th cassette feed sensor is disconnected.
2. Check if the connector J350 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 patterns on the LGC board are short- or open-circuited.
5. Replace the LGC board.
6. Replace the 4th cassette feed sensor.
YES
Is the 4th cassette feed clutch working?
(Perform the output check in the test mode: 03-228)
NO
1. Check if the connector of the 4th cassette feed clutch is disconnected.
2. Check if the connector J350 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 patterns on the LGC board are short- or open-circuited.
5. Replace the 4th cassette feed clutch.
6. Replace the LGC board.
YES
Check the 4th cassette feed roller and separation roller. Replace them if they are worn out.
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