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Main Unit Theory of Operation Fusing Section
2-115
II Composition/Operation
16.4.7 Open-circuited Fusing Pressure Roller Thermistor (incorrect installation)
detection control
• The temperature detected by the Fusing Pressure Roller Thermistor (TH2) during a
warm-up cycle is monitored and, if an abnormal temperature is detected, “warm-up fail-
ure 0501” is displayed.
A. Detection start timing
• A detection sequence is started when the following three conditions are met:
1. At the start of the warm-up control
2. The fusing rollers are turning.
3. The temperature detected by the Heating Roller Thermistor (TH1) is higher than the
correction temperature of the Fusing Pressure Roller.
• If the temperature detected by the Heating Roller Thermistor (TH1) is lower than the cor-
rection temperature of the Fusing Pressure Roller, the internal state in the middle of the
detection sequence is reset and, if the detection conditions are met again, the sequence
is started anew.
B. Detection termination timing
• The temperature of the Fusing Pressure Roller after correction reaches the warm-up
control temperature -3°C (147°C).
• At the end of the warm-up control or post-warm-up control
C. Detection conditions
• The temperature detected by the Heating Roller Thermistor (TH1) after the lapse of 21
sec. after the start of detection sequence does not increase by 3°C or more as compared
with that at the start of the sequence when the Fusing Pressure Roller correction temper-
ature is less than 147°C.
• The temperature after each period of 1 sec. does not increase by 3°C or more as com-
pared with that 21 sec. ago after the detection sequence.
16.4.8 Abnormal temperature increase rate detection control
• The temperature of the Heating Roller is monitored using the Heating Roller Thermistor
(TH1) during a warm-up cycle. If an abnormal temperature increase rate is detected,
“warm-up failure 0500” is displayed.
A. Detection start timing
• The temperature of the Heating Roller is less than the specified level during the warm-up
control.
B. Detection termination timing
• The temperature of the Heating Roller reaches the specified level during the warm-up
control.
C. Detection conditions
1. The temperature of the Heating Roller at the start of the detection is recorded.
2. The temperature of the Heating Roller 1 sec. after the recording is compared with that
recorded.
3. The malfunction is detected if the difference in temperature exceeds 11°C.
4. If the temperature difference is 11°C or less, the current Heating Roller temperature is
recorded and then the detection operation is repeated starting with step 2.
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