B. Fixing Control Circuit
1. Fixing temperature control
The fixing film unit contains a plate-shaped fixing heater to heat the fixing film.
The fixing heater temperature is detected by the thermistor (TH701) on the fixing heater.
When the surface temperature of the fixing heater rises, the resistance value of TH701 decreas-
es, and the voltage of the FIXING HEATER TEMPERATURE DETECTION signal (FSRTH) decreas-
es.
The CPU (IC402) on the engine controller controls the FIXING HEATER DRIVE signal (FSRDO)
based on the voltage of the FSRTH signal in order to bring the fixing heater temperature to the
specified value.
No power is supplied to the fixing heater when the printer is in the STANDBY mode.
When a print instruction command is input from the video controller, the CPU starts the ini-
tial temperature control of the fixing heater.
Figure 2-2-5
At this time, the CPU monitors the FSRTH signal and sets the THERMISTOR SWITCHING sig-
nal (THCHG) to “H” when the fixing heater temperature is low (Initial temperature control) and
to “L” when the temperature is high (Print temperature control) in order to improve the FSRTH
CHAPTER 2
2 - 9
-
+
Q305
35
FSRDO
Fixing heater (H701)
Thermal fuse (FU1131) J301-1
J301-2
FSRTH
J303-1
Fixing film unit
Thermistor
(TH701)
J303-2
+3.3V
SSR301
Q302
Q304
Relay
(RL301)
+24V
Fuse
(FU201)
Fixing heater safety circuit
Engine controller PCB
+3.3V
SW201
RLYD
FSRTH
40
IC402
CPU
+3.3V
13
10
11
IC503
+3.3V
THCHG
43
20
Q303
Summary of Contents for LBP-1000
Page 8: ......
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Page 16: ...2 Paper feeder Figure 1 4 3 1 Paper feeder 2 Cassette CHAPTER 1 1 8 ...
Page 24: ...Figure 1 5 3 CHAPTER 1 1 16 ...
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Page 86: ...CHAPTER 2 2 52 ...
Page 108: ...VII MOTOR FAN A Locations Main motor Cooling fan Figure 3 7 1 CHAPTER 3 3 21 ...
Page 145: ...4 Defective engine controller PCB Action Replace the engine controller PCB CHAPTER 4 4 25 ...
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Page 158: ...Figure 4 9 2 CHAPTER 4 4 38 J1005 J1009 J1006 J2 J1 J3 J9 J1705 J1706 J403 J2 J801 J10 ...
Page 159: ...Figure 4 9 3 CHAPTER 4 4 39 J2003 J2002 J2001 J2131 J2132 J2130 J2110 ...
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