Utax CLP 3521

2HL/2HM/2HN-1
1-4-17
7403 Developing unit M non-installing error
No density detection signal is output
from toner sensor M in developing unit
M.
Faulty connection
of the connector
between the devel-
oping PWB M and
drum relay PWB.
Check the installation of the developing unit
M and drum relay PWB and reinstall them if
necessary (See page 1-5-13).
Defective harness
between drum
relay PWB (YC1)
and engine PWB
(YC34), or
improper connec-
tor insertion.
Reinsert the connector. Also check for conti-
nuity within the connector harness. If none,
remedy or replace the harness.
Defective toner
sensor M.
Replace the developing unit M (See page 1-
5-13).
Defective engine
PWB.
Replace the engine PWB (See page 1-5-
30).
7404 Developing unit Y non-installing error
No density detection signal is output
from toner sensor Y in developing unit Y.
Faulty connection
of the connector
between the devel-
oping PWB Y and
drum relay PWB.
Check the installation of the developing unit
Y and drum relay PWB and reinstall them if
necessary (See page 1-5-13).
Defective harness
between drum
relay PWB (YC1)
and engine PWB
(YC34), or
improper connec-
tor insertion.
Reinsert the connector. Also check for conti-
nuity within the connector harness. If none,
remedy or replace the harness.
Defective toner
sensor Y.
Replace the developing unit Y (See page 1-
5-13).
Defective engine
PWB.
Replace the engine PWB (See page 1-5-
30).
7411 Drum unit K non-installing error
The EEPROM of drum PWB K does not
communicate normally.
Faulty connection
of the connector
between the drum
PWB K and drum
relay PWB.
Check the installation of the drum unit K and
drum relay PWB and reinstall them if neces-
sary (See page 1-5-15).
Defective harness
between drum
relay PWB (YC1)
and engine PWB
(YC34), or
improper connec-
tor insertion.
Reinsert the connector. Also check for conti-
nuity within the connector harness. If none,
remedy or replace the harness.
Installation of
incompatible drum
unit K.
Install drum unit K compatible with the spec-
ifications to the printer.
Defective drum
PWB K.
Replace the drum unit Y (See page 1-5-15).
Defective engine
PWB.
Replace the engine PWB (See page 1-5-
30).
Code Contents
Remarks
Causes Check procedures/corrective measures