Xerox Phaser 3155 User Manual

Phaser 3140/3155/3160 Printer Service Manual2-11
Theory of Operation
Control Panel
The Control Panel is the user interface for 
display of printer status and operation of 
the printer.
Controller Board
The Controller Board consists of the CPU and printer control functions. The CPU 
functions as the bus control, I/O handling,  drivers, and PC interface. The Controller 
Board sends the current image video data  to the Laser Unit and manages the 
electrophotographic printing process. Circuits on the...

2-12Phaser 3140/3155/3160 Printer Service Manual
Theory of Operation
Memory
The Controller Board has Flash and DRAM memory.
• Flash Memory: Stores System Program and can be updated via USB interface.
• DRAM Memory: It is used as Swath Buffer in printing, and System Working 
Memory Area.
Power Supply Board
The Power Supply board consists of low voltage and high voltage circuitry and 
supplies power to the entire printer. 
The low voltage circuit supplies DC power to the printer. It converts 110V/220V to...

Phaser 3140/3155/3160 Printer Service Manual2-13
Theory of Operation
• Environment Recognition Control Method: The THV-PWM ACTIVE is the 
transfer active signal. It detects the re sistance change of the transfer roller 
(due to environmental changes) which alters this voltage feed-back signal. For 
more information, see “Transfer” on page 2-18.
• Output Voltage Control Method: The Transfer Output Voltage is output and  controlled by changing the duty cycle of the THV/PWM signal.
Charge Voltage (MHV)
High...

2-14Phaser 3140/3155/3160 Printer Service Manual
Theory of Operation
Supply
• Output voltage: -400 V ~ -800 VDC ± 50 V (ZENER using, DEV)
• Input contrast of the output stability degree: under ± 5%
Loading contrast: ± 5% or less
• Output voltage rising time: 50 ms Max
• Output voltage falling time: 50 ms Max
• Output Loading range: 10 M Ohm ~ 1000 M Ohm
• Output control signal (BIAS-PWM): The CPU is HV output when PWM is Low.
Power  Supply
The Power Supply (switch-mode power supply, SMPS) supplies DC...

Phaser 3140/3155/3160 Printer Service Manual2-15
Theory of Operation
Ripple & Noise 
Vo ltage
Under 100 mVp-p Under 500 mVp-p
Maximum Output 6 W 48 W
Peak output 7.5 W 60 W Under  100 ms
Protection for 
Loading Shortage 
and Overflowing 
Current Shut down or Fuse 
Protection
Shut down (or 
Output Voltage Drop 
ItemCH1CH2Remark
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2-16Phaser 3140/3155/3160 Printer Service Manual
Theory of Operation
Sensor Input Circuit
Paper Empty Sensing
The Paper Empty (width) Sensor on the Power Supply detects the state of paper 
empty and the state of narrow paper widt
h. If the Paper Empty sensor fails to 
detect paper existence, it can mean that the Paper Tray is empty, or that narrow 
paper is installed.
When the print job comes to the CPU, the pickup action is performed regardless of 
a paper empty condition. If the paper comes through to...

Phaser 3140/3155/3160 Printer Service Manual2-17
Theory of Operation
Exit Sensor
The Exit Sensor, located on the Fuser, detects the media as it exits the Fuser.
The CPU monitors the on/off timing of th
e Exit Sensor signal and determines 
normal operation or the presence of a jam (Jam2). If a paper jam is detected, the 
red LED on the Control Panel illuminates.
Out Bin Full Sensor
The Out Bin Full Sensor detects when the output tray is full If the sensor detects 
the output tray is full, the red LE D on...

2-18Phaser 3140/3155/3160 Printer Service Manual
Theory of Operation
Engine F/W
Control Algorithm
Feeding
The printer feeds the paper from the manual feeder when the Manual Feed Sensor 
indicates that paper is present in the manual feeder.
When feeding from the Paper Tray, the drive of the Pick Up Roller is controlled by 
the Pick Up Solenoid. While paper moves, the occurrence of a jam is judged as 
fo ll ows .
Transfer
The charging voltage, developing voltage, and transfer voltage are controlled by...

Phaser 3140/3155/3160 Printer Service Manual2-19
Theory of Operation
Fusing
The temperature change of the Heat Roller’s surface is detected by the value of 
the Thermistor. The Thermistor resistance is measured using the A/D converter 
through which the CPU can determine the temperature of the Heat Roller. AC 
power is controlled by comparing the target temperature to the value from the 
Thermistor. If the value from the Thermistor is out of the controlled range while 
controlling the fusing process, an...

2-20Phaser 3140/3155/3160 Printer Service Manual
Theory of Operation
Laser Unit 
The Laser Unit receives image data from the PVC or HPVC and makes the latent 
image on the OPC surface. The Laser Unit uses a single beam system. 
The errors related to the Laser Un
it are shown in the table below:
LSU Error Recovery
If the LReady or Hsync error happens, the paper exits out beforehand. The engine 
mode is changed to recovery mode and the engine informs the main system of the 
engine mode. The engine checks...