Canon MF6530 Service Manual - Page 127

Protection Function

Page 127 highlights

Chapter 8 8.2.2.2 Target Temperatures by Mode 0012-7187 This machine controls the fixing temperature according to the "media type" selected in the user mode and the "target temperature" set in the "special mode." The correspondence between each mode and target temperature is as follows: T-8-3 Paper type Cassette Manual pickup feed tray pickup Duplex Fixing mode Target Initial number of initial fixing sheets (*2) temperature (*1) Reamarks Plain paper/colored Yes Yes Yes Plain paper paper/recycled paper/ heavy paper1(81-90g/ m2) 210 deg C 185 deg C 1-30 (A4/LTR) 1-30 (A4/LTR) Special Mode S: OFF Special Mode S: ON Heavy paper2(91 to 105g/m2) - Yes - Heavy paper 210 deg C 1-30 (A4/LTR) Heavy paper3(106 128g/m2) - Yes - Heavy paper H 215 deg C 1-30 (A4/LTR) Transparency - Yes - OHP 195 deg C 1-30 (A4/LTR) Envelopes - Yes - Envelope H /Envelope L 215 deg C 1-5 The controller changes fixing mode by size. Labels - Yes - Heavy paper 210 deg C 1-5 (A4/LTR) 3hole punch paper Yes Yes Yes Plain 210 deg C 1-30 (A4/LTR) Special Mode S: OFF 185 deg C 1-30 (A4/LTR) Special Mode S: ON *1: Target fixing temperature at startup. When the initial temperature of the fixing unit is high, the target temperature is lowered. In the continuous copy mode, the target temperature is lowered. *2: Number of sheets controlled at the initial target temperature. If it is exceeded, the target temperature is lowered. The prescribed number of sheets varies with the paper size. 8.3 Protection Function 8.3.1 Outline 0011-4250 This circuit is installed on the DC controller PCB. It is used to monitor abnormal rise of the fixing temperature at all times. If the main thermistor's output voltage is held below about 0.78 V (about 235 deg C or higher) for at least 1 second or the sub-thermistor's output voltage is held blow about 0.39 V for 0.15 seconds or longer due to the rise in the fixing heater temperature, the relay is turned off and the fixing heater is turned off irrespective of the relay drive signal (RLYD). If the temperature of the fixing heater increases abnormally, on the other hand, to exceed about 228 deg c, the temperature fuse will melt to cut the power to the fixing heater. SW1 F1 P1 Relay circuit AC DC NF Power supply PCB F2 NF Low-voltage power supply circuit J14 Zerocross circuit -14 +3.3V, +5V, +24V ZEROX Heater drive circuit J14 -12 -13 RLYD FSRDRV J103 -1 J103 -3 -2 DC controller PCB ASIC RL1 Heater trigger circuit J15 -1 -3 Fixing unit J113 GND -4 SUBTH -3 GND -2 MAINTH -1 Fixing heater high temperature error detection TH2 TH1 J25 -1 TP -2 H1 F-8-3 8.3.2 Failure Detection 0011-4251 The CPU on the DC controller PCB will identify a fault in the fixing assembly if any of the following conditions (a through d) occurs; as a result, - it will cut the power to the fixing heater. - it will cause the relay drive signal (RYLD) to go '1' to turn off the relay and, at the same time, will communicate the presence of a fault to the image processor PCB. 8-3

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Chapter 8
8-3
8.2.2.2 Target Temperatures by Mode
This machine controls the fixing temperature according to the "media type" selected in the user mode and the "target temperature" set in the "special mode."
The correspondence between each mode and target temperature is as follows:
T-8-3
*1: Target fixing temperature at startup. When the initial temperature of the fixing unit is high, the target temperature is lowered. In the continuous copy mode, the
target temperature is lowered.
*2: Number of sheets controlled at the initial target temperature. If it is exceeded, the target temperature is lowered. The prescribed number of sheets varies with
the paper size.
8.3 Protection Function
8.3.1 Outline
This circuit is installed on the DC controller PCB. It is used to monitor abnormal rise of the fixing temperature at all times. If the main thermistor's output voltage
is held below about 0.78 V (about 235 deg C or higher) for at least 1 second or the sub-thermistor's output voltage is held blow about 0.39 V for 0.15 seconds or
longer due to the rise in the fixing heater temperature, the relay is turned off and the fixing heater is turned off irrespective of the relay drive signal (RLYD).
If the temperature of the fixing heater increases abnormally, on the other hand, to exceed about 228 deg c, the temperature fuse will melt to cut the power to the
fixing heater.
F-8-3
8.3.2 Failure Detection
The CPU on the DC controller PCB will identify a fault in the fixing assembly if any of the following conditions (a through d) occurs; as a result,
- it will cut the power to the fixing heater.
- it will cause the relay drive signal (RYLD) to go '1' to turn off the relay and, at the same time, will communicate the presence of a fault to the image processor PCB.
Paper type
Cassette
pickup
Manual
feed tray
pickup
Duplex
Fixing mode
Target
initial fixing
temperature
(*1)
Initial number of
sheets (*2)
Reamarks
Plain paper/colored
paper/recycled paper/
heavy paper1(81-90g/
m2)
Yes
Yes
Yes
Plain paper
210 deg C
1-30 (A4/LTR)
Special Mode S: OFF
185 deg C
1-30 (A4/LTR)
Special Mode S: ON
Heavy paper2(91
to
105g/m2)
-
Yes
-
Heavy paper
210 deg C
1-30 (A4/LTR)
Heavy paper3(106 -
128g/m2)
-
Yes
-
Heavy paper H
215 deg C
1-30 (A4/LTR)
Transparency
-
Yes
-
OHP
195 deg C
1-30 (A4/LTR)
Envelopes
-
Yes
-
Envelope H /Envelope L
215 deg C
1-5
The controller changes
fixing mode by size.
Labels
-
Yes
-
Heavy paper
210 deg C
1-5 (A4/LTR)
3hole punch paper
Yes
Yes
Yes
Plain
210 deg C
1-30 (A4/LTR)
Special Mode S: OFF
185 deg C
1-30 (A4/LTR)
Special Mode S: ON
Relay
circuit
Fixing unit
P1
NF
NF
ASIC
Zerocross circuit
Heater drive circuit
J14
-12
J103
-3
RLYD
FSRDRV
-13
-2
J14
-14
J103
-1
ZEROX
Power supply PCB
DC controller PCB
AC
DC
F1
F2
SW1
J113
GND
SUBTH
-4
-3
GND
MAINTH
-2
-1
+3.3V, +5V, +24V
Low-voltage power
supply circuit
J15
-1
-3
Fixing heater
high
temperature
error detection
TH1
TH2
-2
-1
RL1
H1
Heater trigger
circuit
J25
TP