Canon CLC 1120 Service Handbook page 237

Code
The developer has deteriorated.
E020
• The developing cylinder fails to
rotate.
• The developing assembly is not
locked.
• The toner concentration (patch
detection) sensor is faulty.
• The developer inside the
developing assembly is faulty.
• The toner level sensor is faulty.
• The concentration sensor is
subjected to stray light (no cover,
front cover open).
• The photosensitive drum has
deteriorated.
• The developer has deteriorated.
• The developing cylinder fails to rotate.
• The developer is not locked.
• The toner concentration sensor is
faulty.
• The developer inside the
developing assembly is not stirred
properly.
• The toner level sensor is faulty.
• The sensor is subjected to stray
light (no cover, front cover open).
• The photosensitive drum has
deteriorated, or the toner level
sensor is faulty.
• The hopper motor is faulty.
• The hopper motor has an open
circuit.
Cause Cause
CHAPTER 5 SELF DIAGNOSIS
Timing of detection
xxB0 When samplings are taken
during copying sequence, the
level of SGNL-M/C/Y is
'1020' or more (when feeding
10 sheets or more
continuously).
xxB1 When samplings are taken
during copying sequence, the
level of REF-M/C/Y set
initially increases (intensity)
by '30%' or more.
xxB2 When samplings are taken
during copying sequence, the
level of PT-SIG-M/C/Y is
'1020' or more and that of PT-
SIG-K is '550' or more.
xxC0 When samplings are taken
during copying sequence, the
level of DENS-M/C/Y/K is
'+3%' (when feeding 20 sheets
continuously).
xxD0 When samplings are taken
during copying sequence, the
level of DENS-M/C/Y/K is
'+3%' (when feeding 20 sheets
or more continuously).
xxE0 When samplings are taken
during copying sequence, the
level of DENS-M/C/Y/K has
exceeded '-5%'.
00FF After the hopper motor has
turned on, the hopper motor
lock signal (HOPMLK) is '0'
for 0.1 sec or more.
xxFF After the hopper motor has
turned on, the hopper motor
lock signal (HOPMLK) is '0'
for 0.1 sec or more (the toner
supply clutch is on).
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