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Table 2-4
Notes: 1. If you print up to 25 envelopes
continuously during normal
temperature control, the target
temperature is held at 183°C. If
y o u
p r i n t
envelopes continuously, the
temperature is held al 178°C.
2. Ii" the thermistor-detected tem-
perature is 50°C or less when
the power is switched ON, this
lemperature control is per-
f o r m e d f o r 1 5 m i n u t e s t o
improve fixing.
The printer has the following three
protection functions to prevent incorrect
activation of the fixing roller:
t T h e C P U m o n i t o r s t h e t h e r m i s t o r
voltage. If it is abnormal, the CPU
detects the fixing unit error. interrupts
the power to the fixing roller heater, and
reports it to the video controller.
. If
the upper roller surface temperature
rises abnormally and the thermistor
voltage falls below about 1.0 V (230°C).
the safety circuil in the power supply
interrupts the power to the fixing roller
heater regardless of the CPU output.
. If
the upper roller surface temperature
rises abnormally and the thermoswitch
temperature
e x c e e d s 2 1 0 ° C . t h e
thermoswitch turns off, interrupting the
power to the fixing roller heater.
m o r e
t h a n
2 5
2. Fixing unit error detection
The CPU assumes a fixing unit error In the
following cases, and informs the video
E r r o r m e m o r y c a p a c i t o r (C202)
charging detection
If the voltage at pin 74 (AN161 of the
CPU is 1.62 V or more (C202 is charged)
when the power is switched ON
Thermistor broken-wire detection
b.
If the upper roller temperature does not
reach 33°C within 22 seconds of the
fiiing roller heater being turned ON
F i x i n g r o l l e r h e a t e r b r o k e n - w i r e
detection
If the upper roller temperature does not
reach the standby temperature within
200 seconds of the fling roller heater
being turned ON
Broken-wire detection after the fixing
unit becomes ready
If the upper roller temperature reaches
140°C in the standby state or during
printing
e.
Thermistor short detection
If the voltage of the FIXING ROLLER
S U R F A C E T E M P E R A T U R E s i g n a l
lFSRTH1 is 0.94 V (230°C) or less
When the CPU detects a fixing error, the
following are performed:
Switches the fling roller heater OFF.
11
Sets the output from pin 27 (P63] to
21
"H" and charges the error memory
capacitor (C2021.
Sets the RELAY DRIVE signal [RLD) to
31
"L", switches the relay OFF in the
power supply, and interrupts the power
to the fixing roller heater.
2 - 31
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