Service manual

Chapter 2
2-34
2.4.4 Cassette Pickup Unit
2.4.4.1 Pickup from the Cassette
0008-2078
When the cassette is used as the source of paper, the machine operates as follows to make sure that a single sheet of paper is picked from the cassette:
1. When the SCNT board sends the pickup command, the DCNT board drives the main motor (DCM701) in response.
2. A specific period of time after the main motor (DCM701) starts to rotate, the cassette pickup solenoid (SL9) goes on.
3. The cassette pickup roller starts to rotate, thereby picking up paper and moving it to the inside of the machine.
4. The separation pad makes sure that no more than a single sheet of paper is picked up. The paper is then moved as far as the registration roller.
5. When the paper reaches the registration roller, the registration shutter makes sure that it is not askew. The paper is then moved at a speed suited to its type as
instructed by the SCNT board.
6. Thereafter, the ITB home position detection mechanism goes on, and the DCNT board turns on the registration clutch (CL1). As a result, the drive of the motor
(DCM701) reaches the registration roller, and the print paper is moved to the secondary transfer roller.
7. The DCNT board uses the secondary transfer roller shift mechanism to lock the secondary transfer roller to the ITB. At the same time, the roller shift clutch (CL2)
goes on so that the drive of the motor (DCM701) reaches the secondary transfer roller. The toner image on the ITB is then transferred to the print paper, which
thereafter is moved to the fixing/delivery assembly.
2.4.5 Manual Feed Pickup Unit
2.4.5.1 Multi-purpose Tray Pick-up
0007-4998
When printing from the multi-purpose tray, paper on it is fed into the printer one by one.
The following describes the multi-purpose tray pick-up operation:
1) When a print command is input from the SCNT Board, the DCNT Board drives the main motor (DCM701) to rotate the ITB.
2) Within a specified period after the start of the DCM701 rotation, the multi-purpose tray pick-up solenoid (SL92) goes on.
3) After a lifting plate for the multi-purpose tray has moved up, the multi-purpose tray pick-up roller starts to rotate. This allows paper on the tray to be fed into the
printer.
4) After a multiple-fed paper is removed with the separation pad, paper is sent to the registration roller.
5) After the skew of paper is corrected with the registration shutter, a feed speed is changed based on a paper type specified from the SCNT Board in feed speed
control.
6) Then, the SCNT Board let in the registration clutch (CL1) within a specified period in ITB home position detection function. This allows the drive of the DCM701
to transmit to the registration roller and paper to be fed to the secondary transfer roller.
7) The SCNT Board press the secondary transfer roller against the ITB in secondary transfer roller engaging control. Simultaneously, it lets in the roller-engaging
clutch (CL2). This allows the drive of the DCM701 to transmit to the secondary transfer roller. Toner is transferred onto paper on the ITB and paper is fed to
the fixing/delivery unit.
2.5 Fixing Unit
2.5.1 Overview/Configuration
2.5.1.1 Outline
0011-6403
This printer utilizes an on-demand fixing method which is configured as shown in the figure below.
T-2-7
F-2-49
This control circuit has the following four controls and functions:
- Heater temperature control-Maintains the fixing heater at a specified temperature.
- Flicker prevention function-Prevents flicker caused by attaching lighting apparatuses to the power source to which the printer is connected.
- Protective function-Shuts off the power supply to the fixing heater when the heater is overheating.
- Failure detection-Monitors the abnormalities of the fixing unit and when an abnormality occurs, shuts off the heater and notifies it to the video controller.
- Heater:
One heater is utilized in the fixing unit.
Fixing heater (H1): For fixing film heating (ceramic heater)
- Thermistors:
Two thermistors are utilized in the fixing unit.
Main thermistor (TH1): For fixing heater temperature control (contact thermistor)
Sub thermistor (TH2): For fixing heater temperature rise detection at its end (contact thermistor)
- Thermoswitch:
One thermoswitch is placed on top of the fixing heater (non contact type). When the fixing
heater is abnormally overheated, the switch opens and cut off the power supply to the heater.
Fixing sleeve unit
Main thermistor
(TH1)
Sub thermistor
(TH2)
Pressure roller
Fixing unit
Thermoswitch
(TP)
DCNT board
Power supply unit
Fixing heater
FIXING HEATER
DRIVE signal
Fixing
control
circuit
FIXING TEMPERATURE DETECTION signal
CPU
Fixing
heater
safety
circuit
IC101