Epson TM-U220 Series Service Manual page 46

Confidential
Cannot pass one of the tests for a sensor
Cannot pass the NE (near-end) sensor test
Table 3-22 Test for the NE Sensor Fails
Probable part/probable cause Checkpoints
NE lead wire set (1096)
Micro switch (1039)
NE detector holder (1042)
NE detector lever (1043)
Main circuit board unit (201)
Cannot pass the test for the RE (real end) sensor
Table 3-23 Test for the RE Sensor Fails
Probable part/probable cause Checkpoints
HP board assembly (518)
Paper end assembly (514)
Main circuit board unit (201)
3-18 Troubleshooting
Check connection. Ensure cable is
plugged in. Be sure the NE lead wire set
(1096) is connected to the connectors
below.
Micro switch (1039)
Connector (CN6) on the main circuit
board unit (201)
Check the continuity with a tester. Make
sure wires are not cut or shorted out. Verify
that wires are arranged correctly.
Check micro switch (1039) operation.
Make sure the continuity changes when
you operate the switch.
Check the operation. Make sure the NE
detector lever rotates smoothly.
Check the parts for defects.
Make sure connectors (CNC2 and CN6)
are connected.
Check the connection. Make sure the
cable is plugged in. Make sure the
connector on the HP board assembly
(518) is connected to connector (CN4) on
the main circuit board unit (201).
Check the continuity with a tester. Make
sure wires are not cut or shorted out. Be
sure wiring is arranged correctly.
Check the continuity of paper end
assembly (514) wires with a tester. Make
sure wires are not cut or shorted out. Be
sure wiring is arranged correctly.
Check the parts for defects.
Make sure connector (CN4) is connected.
Action to correct the problem
Plug in the connector. Completed if
the test passes.
Replace the NE lead wire set.
Completed if the test passes.
Replace the near-end sensor.
Completed if the test passes.
Replace the NE detector holder or
lever. Completed if the test passes.
Replace the main circuit board unit.
Completed if the test passes.
Action to correct the problem
Plug in the connector. Completed if
the test passes.
Replace the HP board assembly
(518). Completed if the test passes.
Replace the paper end assembly.
Completed if the test passes.
Replace the main circuit board unit.
Completed if the test passes.
Rev. B