Ricoh FT1008/208 Service Manual Plover

FT1008/FT1208

(Plover, A226/A227)

Service Manual

Issued April 8, 1998, Ricoh CO., LTD.

IMPORTANT SAFETY NOTES

PREVENTION OF PHYSICAL INJURY

1. Before disassembling or assembling any parts of the copier, make sure that the power cord is unplugged.

2. The wall outlet should be near the copier and easily accessible.

3. If any adjustment or operation check has to be made with exterior covers off or open while the main switch is turned on, keep hands away from electrified or mechanically driven components.

4. If the Start key is pressed before the copier completes the warm-up period the Ready indicator will alternately light green and red. When in this condition, keep hands away from mechanical and electrical components, as the copier will start making copies as soon as the warm-up period is completed.

5. The inside and the metal parts of the fusing unit become extremely hot while the copier is operating. Be careful to avoid touching those components with your bare hands.

HEALTH SAFETY CONDITIONS

1. Toner and developer are non-toxic, but if you get either of them in your eyes by accident, it may cause temporary eye discomfort. Try to remove with eye drops or flush with water as first aid. If unsuccessful, get medical attention.

2. Never operate the copier without the ozone filter installed.

OBSERVANCE OF ELECTRICAL SAFETY STANDARDS

1. The copier must be maintained by a trained customer service representative.

SAFETY AND ECOLOGICAL NOTES FOR DISPOSAL

1. Do not incinerate the CTDM. Toner dust may ignite suddenly when exposed to open flame.

2. Dispose of the CTDM and organic photoconductor in accordance with local regulations. (These are non-toxic supplies.)

3. Dispose of replaced parts in accordance with local regulations.

TABLE OF CONTENTS

1. OVERALL MACH INE INFORMATION........................................1-1

1.1 SPECIFICATIONS.................................................................................... 1-1

1.2 COPY PROCESSES AROUND THE DRUM............................................ 1-3

1.3 MECHANICAL COMPONENT LAYOUT................................................... 1-5

1.4 ELECTRICAL COMPONENT LAYOUT.................................................... 1-6

1.5 ELECTRICAL COMPONENT DESCRIPTIONS........................................ 1-7

2. DETAILED DESCRIPTION.......................................................... 2-1

2.1 DRUM.......................................................................................................2-1

2.1.1 OPC DRUM CHARACTERISTICS................................................... 2-1

2.2 CHARGE .................................................................................................. 2-2

2.2.1 OVERVIEW ..................................................................................... 2-2

2.3 OPTICS .................................................................................................... 2-3

2.3.1 OVERVIEW ..................................................................................... 2-3

2.3.2 SCANNER DRIVE ........................................................................... 2-4

2.3.3 LENS AND 4TH/5TH MIRROR DRIVE (A227 MACHINE ONLY).... 2-5

2.3.4 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS).......... 2-6

2.3.5 EXPOSURE LAMP VOLTAGE CONTROL...................................... 2-7

2.4 ERASE.................................................................................................... 2-12

2.4.1 OVERVIEW ................................................................................... 2-12

2.4.2 LEAD EDGE ERASE..................................................................... 2-13

2.4.3 SIDE ERASE (A227 MACHINES ONLY)....................................... 2-13

2.4.4 TRAILING EDGE ERASE..............................................................2-13

2.5 DEVELOPMENT..................................................................................... 2-14

2.5.1 OVERVIEW ................................................................................... 2-14

2.5.2 TONER SUPPLY MECHANISM.................................................... 2-15

2.5.3 DEVELOMENT BIAS FOR IMAGE DENSITY CONTROL............. 2-16

2.5.4 TONER END CONDITION............................................................. 2-18

2.6 IMAGE TRANSFER................................................................................ 2-20

2.7 DRUM CLEANING.................................................................................. 2-21

2.8 QUENCHING.......................................................................................... 2-22

2.9 PAPER FEED AND REGISTRATION..................................................... 2-23

2.9.1 OVERVIEW ................................................................................... 2-23

2.9.2 PAPER FEED MECHANISM......................................................... 2-24

2.9.3 REGISTRATION MECHANISM..................................................... 2-25

2.9.4 BY-PASS FEED............................................................................. 2-26

2.9.5 PAPER FEED AND MISFEED DETECTION TIMING.................... 2-27

2.10 IMAGE FUSING.................................................................................... 2-28

2.10.1 OVERVIEW ................................................................................. 2-28

2.10.2 FUSING LAMP CONTROL.......................................................... 2-29

2.10.3 FUSING LAMP CONTROL CIRCUIT........................................... 2-30

3. INSTALLA TION...........................................................................3-1

3.1 INSTALLATION REQUIREMENTS .......................................................... 3-1

Error! No text of specified style in document.

1.2.1 ENVIRONMENT ..............................................................................3-1

1.2.2 MACHINE LEVEL............................................................................ 3-1

1.2.3 MINIMUM SPACE REQUIREMENTS.............................................. 3-2

1.2.4 POWER REQUIREMENTS.............................................................. 3-2

3.2 MACHINE INSTALLATION....................................................................... 3-2

0 XXX 0000

4. SERVICE TABLES......................................................................4-1

4.1 SERVICE REMARKS............................................................................... 4-1

4.1.1 GENERAL CAUTIONS.................................................................... 4-1

4.1.2 DRUM.............................................................................................. 4-1

4.1.3 CTDM (CLEANING TONER DEVELOPMENT MAGAZINE)............ 4-2

4.1.4 CHARGE CORONA UNIT ............................................................... 4-2

4.1.5 ERASE LAMP.................................................................................. 4-2

4.1.6 OPTICS ........................................................................................... 4-3

4.1.7 TRANSFER CORONA..................................................................... 4-3

4.1.8 FUSING UNIT.................................................................................. 4-3

4.1.9 PAPER FEED.................................................................................. 4-3

4.1.10 OTHERS........................................................................................ 4-4

4.2 PROGRAM MODES................................................................................. 4-5

4.2.1 BASIC OPERATION........................................................................ 4-5

4.2.2 SP MODE........................................................................................ 4-6

4.2.3 SP MODE QUICK REFERENCE TABLE......................................... 4-8

4.2.4 UP MODE AND SP MODE CROSS REFERENCE TABLE.............4-9

4.2.5 SERVICE PROGRAM MODE........................................................ 4-10

4.2.6 CLEAR ALL MEMORY PROCEDURE........................................... 4-25

4.3 SERVICE TABLES................................................................................. 4-26

4.3.1 VARIABLE RESISTORS................................................................ 4-26

4.4 SERVICE CALL CONDITIONS............................................................... 4-27

4.5 ERROR CODE FOR USER....................................................................4-32

5. SERVICE MA INTENANCE..........................................................5-1

5.1 MAINTENANCE ITEMS AND METHODS ................................................ 5-1

6. REPLACEMENT A ND ADJUSTMENT........................................ 6-1

6.1 EXTERIOR ............................................................................................... 6-1

6.1.1 EXTERIOR COVER/EXPOSURE GLASS REMOVAL..................... 6-1

6.1.2 UPPER UNIT REMOVAL................................................................. 6-2

6.2 OPTICS .................................................................................................... 6-3

6.2.1 EXPOSURE LAMP REMOVAL........................................................ 6-3

6.2.2 1ST MIRROR REMOVAL................................................................ 6-4

6.2.3 EXPOSURE LAMP THERMOFUSE REMOVAL.............................. 6-5

6.2.4 2ND AND 3RD MIRRORS REMOVAL............................................. 6-6

6.2.5 4TH MIRROR REMOVAL................................................................ 6-7

6.2.6 5TH MIRROR REMOVAL (A227 MODEL)....................................... 6-8

6.2.7 5TH MIRROR REMOVAL (A226 MODEL)....................................... 6-9

6.2.8 LENS AND 4TH/5TH MIRROR POSITION ADJUSTMENT (A227

MODEL)................................................................................................... 6-10

6.2.9 LENS AND MIRROR MOTOR REMOVAL..................................... 6-11

6.2.10 SCANNER WIRE REMOVAL....................................................... 6-12

6.3 AROUND THE DRUM UNIT................................................................... 6-14

6.3.1 OPC DRUM REMOVAL................................................................. 6-14

6.3.2 CHARGE CORONA UNIT REMOVAL...........................................6-15

6.3.3 ERASE LAMP REMOVAL ............................................................. 6-16

6.4 PAPER FEED.........................................................................................6-18

6.4.1 PAPER FEED CLUTCH REMOVAL.............................................. 6-18

6.4.2 PAPER FEED ROLLER REMOVAL.............................................. 6-19

6.4.3 REGISTRATION SOLENOID REMOVAL...................................... 6-20

6.5 FUSING.................................................................................................. 6-21

6.5.1 FUSING UPPER UNIT REMOVAL................................................ 6-21

6.5.2 PRESSURE ROLLER REMOVAL................................................. 6-22

6.5.3 FUSING LAMP REMOVAL............................................................ 6-23

6.5.4 HOT ROLLER STRIPPER PAWL REMOVAL................................ 6-24

6.5.5 HOT ROLLER REMOVAL ............................................................. 6-25

6.5.6 FUSING THERMISTOR REMOVAL.............................................. 6-26

6.5.7 FUSING THERMOFUSE REMOVAL ............................................. 6-27

6.5.8 FUSING PRESSURE ADJUSTMENT............................................ 6-28

6.6 OTHERS................................................................................................. 6-29

6.6.1 TRANSFER CORONA UNIT REMOVAL.......................................6-29

6.6.2 MAIN MOTOR REMOVAL............................................................. 6-30

6.6.3 OZONE FILTER REMOVAL.......................................................... 6-31

6.6.4 TONER END SENSOR REMOVAL............................................... 6-32

6.6.5 POWER PACK REMOVAL............................................................ 6-33

6.6.6 POWER PACK OUTPUT ADJUSTMENT ...................................... 6-36

6.6.7 TRANSFER CORONA CURRENT ADJUSTMENT ....................... 6-37

6.6.8 GRID VOLTAGE ADJUSTMENT................................................... 6-38

6.6.9 BIAS VOLTAGE ADJUSTMENT.................................................... 6-39

6.7 COPY QUALITY ADJUSTMENT............................................................ 6-40

6.7.1 IMAGE DENSITY ADJUSTMENT.................................................. 6-40

6.7.2 REGISTRATION ADJUSTMENT................................................... 6-44

6.7.3 LEAD EDGE ERASE MARGIN ADJUSTMENT............................. 6-44

6.7.4 VERTICAL MAGNIFICATION ADJUSTMENT...............................6-45

6.7.5 HORIZONTAL MAGNIFICATION ADJUSTMENT (A227 ONLY)... 6-45

6.7.6 FOCUS ADJUSTMENT (A227 ONLY)........................................... 6-46

6.7.7 PARALLELOGRAM IMAGE ADJUSTMENT.................................. 6-47

6.8 CONNECTOR LAYOUT......................................................................... 6-48

6.8.1 MAIN CONTROL BOARD (MCB) .................................................. 6-48

6.8.2 POWER SUPPLY UNIT (PSU)...................................................... 6-49

6.8.3 NOISE FILTER.............................................................................. 6-49

6.8.4 POWER PACK............................................................................... 6-50

iii

28 February 1998 SPECIFICATIONS

1. OVERALL MACHINE INFORMATION

1.1 SPECIFICATIONS

Configuration: Desk top Copy Process: Dry electrostatic transfer system Originals: Sheet/Book Original Size: Maximum: A4/8½" x 14" Copy Paper Size Paper tray feed:

A5, B5, A4, 5½" x 8½", 8½" x 11", 8½" x 13", 8½" x 14"

By-pass feed:

Maximum: A4/8½" x 14" Minimum: A6/8½" x 5½"

Copy Paper Weight: Paper tray feed: 60 to 90 g/m2, 16 to 24 lb

By-pass feed: 60 to 180 g/m2, 16 to 48 lb

Reproduction Ratios:

Enlargement

Full Size 100% 100%

Reduction

Metric Version Inch Version

141% 122%

82% 71%

141%

93% 78% 70%

Overall

Information

Zoom (A227 model only): From 70% to 141% in 1% steps Copy Speed: 8 copies/minute (A4/8½" x 11") Warm-up Time:

Less than 15 seconds (at 23°C/73°F) First Copy Time: Less than 10 seconds (A4/8½" x 11") Copy Number Input: Up/Down key, 1 to 50 Manual Image Density

4 steps including halftone Selection:

Automatic Reset: 1 minute standard setting; can also be set to 3

minutes or no auto reset Paper capacity: Paper Tray: 250 sheets (80 g/m2/20 lb)

By-pass feed entrance: 1 sheet (180 g/m2/48 lb) Toner Replenishment: CTDM exchange (140g/CTDM) Copy Tray Capacity: 50 sheets

1-1

SPECIFICATIONS 28 February 1998

Power Source: 120 V, 60 Hz, more than 10 A (for North America)

220 ~ 240 V, 50/60 Hz, more than 6 A

(for Europe/Asia )

220 V, 50/60 Hz, more than 6 A (for Asia) Power Consumption:

Maximum 1,200 W/1,300W

Copy cycle 400 W/450W

Warm-up 750 W/790W

Stand-by 55 W/91W

Auto Shut-off 5W/5W

(120 V machines/230 V machines)

Dimensions: Width: 485 mm, 19.1"

Depth: 385 mm, 15.2"

Height: 260 mm, 10.2" Noise Emissions:

Sound pressure level at the operator position

Sound power level in stand-by condition

Sound power level during copy cycle

The measurements were made according to ISO 7779

Weight: Less than 16.5 kg, 36.4 lb

Less than 55 dB Less than 40 dB Less than 62 dB

Energy Star Enabled by SP77—default is ON)

Sleep time selected by SP14—default is 30 min utes

(Note: When in sleep mode, only the Start indicator is

on (blinking green). To restore operation, press any

key other than the Start key.)

1-2

28 February 1998 COPY PROCESSES AROUND THE DRUM

1.2 COPY PROCESSES AROUND THE DRUM

A227V500.WMF

Overall

Information

1. Drum Charge

In the dark, the charge corona unit gives a uniform negative charge to the organic photoconductor (OPC) drum. The charge remains on the surface of the drum because the OPC drum has a high electrical resistance in the dark.

2. Exposure

An image of the original is reflected to the drum surface via the optics assembly. The charge on the drum surface is dissipated in direct proportion to the intensity on the reflected light, thus producing an electrical latent image on the drum surface.

3. Erase

The erase lamp illuminates the area of the charged drum surface that will no t be used for the copy image. The resistance of the drum in the illuminated areas drops and the charge on those areas dissipates.

4. Development

Positively charged toner is attracted to the negatively charged areas of the drum, thus developing the latent image. (The positive triboelectric charge is caused by friction between the carrier and toner particles.)

5. Image Transfer

Paper is fed to the drum surface at the proper time so as to align the copy paper and the developed image on the drum surface. Then, a strong negative charge is applied to the back side of the copy paper, producing an electrical force which pulls

1-3

COPY PROCESSES AROUND THE DRUM 28 February 1998

the toner particles from the drum surface to the copy paper. At the same time, the copy paper is electrically attracted to the drum surface.

6. Cleaning

The cleaning blade scrapes any toner that was not transferred off of the drum.

7. Quenching

Light from the quenching lamp electrically neutralizes the drum surface.

1-4

28 February 1998 MECHANICAL COMPONENT LAYOUT

1.3 MECHANICAL COMPONENT LAYOUT

1. 2

mirror

3 4 5 6

8 9

Overall

Information

A227V501.WMF

9. Development roller

141516

17. Drum•

2. 1st mirror

3. Exposure lamp

4. Quenching lamp

5. Charge corona unit

6. Lens

7. 6th mirror

8. Erase lamp

10. 4th mirror

11. 5th mirror

12. By-pass feed table

13. Relay rollers

14. Paper feed rollers

15. Registration rollers

16. Transfer corona unit

18. Cleaning blade

19. Pressure roller

20. Exit rollers

21. Copy tray

22. Hot roller

23. 3rd mirror

1-5

ELECTRICAL COMPONENT LAYOUT 28 February 1998

1.4 ELECTRICAL COMPONENT LAYOUT

A227V502.WMF

A227V503.WMF

1-6

28 February 1998 ELECTRICAL COMPONENT DESCRIPTIONS

1.5 ELECTRICAL COMPONENT DESCRIPTIONS

Refer to the electrical component layout and the point-to-point diagram on the waterproof foldout sheet for symbols and index numbers.

Symbol Name Function Index No.

Motors

M1 Main Motor

M2 Exhaust Fan Motor Removes heat from around the fusing

M3 Scanner Drive Motor Drives the scanners (1st and 2nd). 6 M4 Lens and Mirror Motor

(A227 machines only)

Clutches

CL1 Paper Feed clutch

Switches

SW1 Interlock Switch Cuts all power when the upper unit is

SW2 VL Switch Changes the light intensity of exposure

Sensors

S1 ADS Sensor Detects the background density of the

S2 Registration Sensor Detects paper end condition. Checks if

S3 Lens and Mirror H. P.

Sensor (A227 machines only)

S4 Scanner H. P. Sensor

S5 Toner End Sensor Detects toner end condition. 12 S6 Exit Sensor Detects misfeeds. 20

Solenoid

SOL1 Registration Solenoid Releases the stopper, synchronizing

Printed Circuit Boards

PCB1 Main Control Board Controls all copier functions. 8 PCB2 Power Pack Provides high voltage for the charge

PCB3 Power Suppl y Board Generates 5 Vdc and 24 Vdc outputs

Drives all the main unit components except for the optics unit and fans.

unit and blows the ozone built up around the charge corona unit to the ozone filter. Prevents build-up of hot air in the optics cavity.

Moves the lens and 4th/5th mirror positions in accordance with the selected magnification.

Transfers main motor drive to the paper feed roller.

opened.

lamp.

original.

paper is set on the by-pass feed table. Informs the CPU when the lens and

th/5th

mirror assembly are at the home

position (full size position). Informs the CPU when the 1

is at the home position.

the paper-feed timing with the original scan.

corona, transfer corona, and development bias.

from 120 Vac or 230 Vac inputs. Drives the exposure lamp, fusing lamp, and main motor.

scanner

Overall

Information

1-7

ELECTRICAL COMPONENT DESCRIPTIONS 28 February 1998

PCB4 Operation Pan el Bo ar d

PCB5 Noise Filter Removes electrical noise from the

Lamps

L1 Ex posur e Lamp

L2 Fusing Lamp Provides heat to the hot roller. 27 L3 Quenching Lamp (QL) Neutralizes any charge remaining on

L4 Erase Lamp

Others

TH1 Optics Thermistor Monitors the temperature around the

TH2 Fusing Thermistor Monitors the fusing temperature. 26

TF1

TF2 Fusing Thermofuse Provides back up overheat protection

CO Total Counter Keeps a count of the total copies

Exposure Lamp Thermofuse

Informs the CPU of the selected modes and displays the machine condition on the panel.

input power.

Applies high intensity light to the original for exposure.

the drum surface after cleaning. Discharges the drum outside of the

image area. (Provides leading/trailing edge and side erase.)

exposure lamp for overheat protection.

Provides back up overheat protection around the exposure lamp.

in the fusing unit.

made. (option)

—

1-8

3 April 1998 DRUM

2. DETAILED DESCRIPTION

2.1 DRUM

2.1.1 OPC DRUM CHARACTERISTICS

The OPC (Organic Photoconductor) Drum used in this machine is small in diameter (30 mm), ensuring good paper separation. An OPC drum has the characteristics of:

1. Being able to accept a high negative electrical charge in the dark. (The

electrical resistance of a photoconductor is high in the absence of light.)

2. Dissipating the electrical charge when exposed to light. (Exposure to light

greatly increases the conductivity of a photoconductor.)

3. Dissipating an amount of charge in direct proportion to the intensity of the light.

That is, where stronger light is directed to the photoconductor surface, a smaller voltage remains on the drum.

4. Being less sensitive to changes in temperature (when compared to selenium F

type drums).

5. During the drum’s life, drum residual voltage gradually increases and the

photoconductive surface becomes worn. Therefore, some compensation for these characteristics is required.

Detailed

Descriptions

2-1

CHARGE 3 April 1998

2.2 CHARGE

2.2.1 OVERVIEW

[A]

This machine uses a single wire scorotron to charge the drum. The corona wire [A] generates a corona of negative ions when the power pack applies a negative voltage (approximately -4.7 kV). The stainless steel grid plate [B] ensures that the drum coating receives a uniform negative charge (-880 V applied by the power pack) as it rotates past the corona.

[B]

The charge corona unit contains a wire cleaner for user maintenance.

A227D500.WMF

The exhaust fan [C] causes a flow of air through the charge corona section. This prevents an uneven build-up of negative ions that can cause uneven image density. The exhaust fan also cools the optics cavity.

An ozone filter [D], which adsorbs ozone (O3) generated by the charge corona, is located behind the exhaust fan. The ozone filter decreases in efficiency over time as it adsorbs ozone. The expected life of the ozone filter is 30k copies.

[C]

[D]

A227D501.WMF

2-2

3 April 1998 OPTICS

2.3 OPTICS

2.3.1 OVERVIEW

A227D502.WMF

During the copy cycle, an image of the original on the exposure glass is reflected onto the drum surface through the optics assembly.

Detailed

Descriptions

This machine has five (metric version) or four (inch version) standard reproduction ratios (A227 machine only), and reproduction ratios in one-percent steps from 70% to 141% by zoom function. A stepper motor is used to change the positions of the lens and the 4th/5th mirrors to enlarge/reduce the image perpendicular to the scanning direction. Changes in reproduction ratio in the scanning direction are achieved by changing the scanner speed (A227 machine only).

The CPU monitors the temperature around the optics through a thermistor that is located on the scanner frame. When the temperature reaches 43°C, the machine stops copying and displays “U1” on the operation panel. Then the machine moves the scanner to the return position, turns off the fusing lamp, and starts rotating the exhaust fan faster to cool the optics cavity. After the temperature drops below 40°C, the machine returns the scanner to the home position, turns on the fusing lamp, and rotates the fan at the normal speed.

Additionally, a thermofuse on the fir st scanner provides back up overheat protection. It opens if the temperature reaches 128°C and cuts ac power to the exposure lamp.

2-3

OPTICS 3 April 1998

2.3.2 SCANNER DRIVE

[G]

[E]

[A]

[F]

[C]

[D]

[B]

A227D503.WMF

A stepper motor [A] is used to drive the scanner. The first scanner [B] consists of the exposure lamp and the first mirror. The second

scanner [C] consists of the second and third mirrors. The scanner drive motor drives the first and second scanners using a scanner drive wire [D] via a pulley [E]. Both of the scanners move along the guide rod [F]. The second scanner speed is a half of the first scanner speed.

The home position sensor [G] detects when the scanner is at the home position. The scanner return position is determined by counting the scanner motor drive pulses.

2-4

3 April 1998 OPTICS

2.3.3 LENS AND 4TH/5TH MIRROR DRIVE (A227 MACHINE ONLY)

[B]

[D]

[A]

[C]

[E]

[F]

A227D504.WMF

Drive from the lens motor [A] is transmitted to the timing belt [B] on which the lens unit [C] is clamped. The lens position is changed to provide the proper optical distance between the lens and the drum surface corresponding to the selected reproduction ratio. The home position sensor [D] detects when the lens is at its home position. The main control boards keeps track of the lens position based on the number of pulses sent to the lens motor.

Detailed

Descriptions

Drive from the lens motor is also transmitted to the 4th/5th-mirror drive cam [E]. As the lens unit position is changed, the cam rotates to change the 4th/5th-mirror [F] position to provide proper the focal distance between the lens and the drum surface.

2-5

OPTICS 3 April 1998

2.3.4 AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

[A]

A227D505.WMF

A227D506.WMF

In ADS mode, the original background density is sensed by the ADS sensor [A] and the CPU determines an appropriate development bias voltage for the original to prevent dirty background from appearing on copies.

The sensor, a photodiode, is mounted on the upper front frame. The sensor cover has a hole to allow the light reflected from the original to fall directly onto the sensor.

Sampling starts 6 millimeters “a” from the leading edge of the original and continues for 15.0 millimeters “b” f rom the leading edge of original in full size mode. These lengths “a” and “b” will vary depending on the selected reproduction ratio.

The photosensor circuit converts the light intensity to a voltage. The detected voltage is amplified and sent to the main control board. The output from the sensor is adjusted to 2.5 volts for a normal white original. The sensor outputs a lower voltage as less light is reflected from the original (the background is darker). The CPU compares the maximum detected voltage with the ADS reference voltage (2.5 ± 0.2 volts) and compensates the copy image density by changing the development bias voltage.

2-6

3 April 1998 OPTICS

2.3.5 EXPOSURE LAMP VOLTAGE CONTROL

The main board controls the exposure lamp voltage through the power supply board. The copy image density is controlled by the lamp intensity and development bias. This section explains how the exposure lamp voltage control affects the copy image density.

Base Lamp Voltage Setting

The base lamp voltage is determined by the SP48 setting.

Base Lamp Voltage =

SP48 value x 0.5 (120 V machines)

SP48 value x 1.0 (230 V machines)

The default settings (may not equal to factory settings) of SP48 are:

for 120 V machines (= 64 V)

128

for 230 V machines (= 120 V)

120

Increasing the value makes the copy image lighter. The maximum value of the lamp voltage setting including compensation factors

(see following) is 180 for 230-volt models and 194 for 120-volt models. For 120-volt machines, the actual lamp voltage is one-half the lamp voltage setting; therefore, the maximum lamp voltage is 97 volts. For 230-volt machines the actual lamp voltage is the same as the lamp voltage setting; so, the maximum voltage is 180 volts.

Detailed

Descriptions

Compensation Factors

The base lamp voltage is shifted by several factors as discussed in the following sections.

NOTE:

In the following tables, the default settings are in bold type.

1. Reproduction Ratio Correction

The exposure lamp voltage increases or decreases depending on the magnification ratio. This compensates for the change in concentration of light on the drum.

Magnification Ratio Exposure Lamp

70% to 99% -1 step

100% 0

101% to 141% +1 step

2-7

OPTICS 3 April 1998

2. Image Density Adjustment Setting (SP34)

SP34 can adjust the copy image density to adapt the machine to its operating environment. Depending on the SP34 setting, both the exposure lamp voltage and the development bias may change.

SP34 (This can also be changed by UP1.)

SP34 Setting Setting Exposure Lamp

Voltage Change

0Normal 0 0

1 Light 0 -40 V 2Dark 0 +40 V 3 Lighter +3 steps -40 V 4 Darker -3 steps +40 V 5 Lightest +7 steps -40 V 6 Darkest -7 steps +40 V

Development

Bias Change

1 step = 0.5 V (120 V machines) or 1.0 V (230 V machines)

3. Image Density Setting Position

The operation panel has four image density level positions. Depending on the position, the exposure lamp base voltage is changed. (ADS is the default.)

Photo Mode Darker ADS Lighter

0 - 6 steps 0 + 6 steps

In the photo mode, the exposure lamp voltage is unchanged; however, the development voltage is changed to improve the copy image for halftone originals. (Refer to Development section.)

(Image Density Adjustment At Darker Setting Position)

There are two SP modes which can adjust the image density when the “Darker” position is selected on the operation panel. Both SP modes change the exposure lamp voltage as shown below.

SP35: Coarse Adjustment (This can also be changed by the UP2)

SP35 Setting Setting Exposure Lamp Voltage

0 Normal -6 steps

1 Darker -8 steps 2 Darkest -10 steps

2-8

3 April 1998 OPTICS

SP38: Fine Adjustment

Setting SP38 Setting Lamp Voltage Change

Darkest 0 -3 steps

1 -2 steps 2 -1 step

4+1 step 5+2 steps

Lightest 6 +3 steps

(Image Density Adjustment at Lighter Setting Position)

There are two SP modes which can adjust the image density when the “Lighter” position is selected on the operation panel. Only the SP mode (SP39) for the fine adjustment of the image density changes the exposure lamp voltage. The coarse adjustment (SP36) changes the development bias (see Development section).

Detailed

Descriptions

SP39: Fine Adjustment

Setting SP39 Setting Lamp Voltage Change

Darkest 0 -3 steps

1 -2 steps 2 -1 step

4+1 step 5+2 steps

Lightest 6 +3 steps

(Image Density Adjustment At Photo Mode Position)

The image density in the Photo mode can be changed by the SP64. The exposure lamp voltage and the base development bias are changed by SP64

as shown in the table. SP64 (This can also be changed by UP4.)

Settings No. Base Bias Voltage

Lightest 0 -270 V +4 steps

1 -270 V +2 steps 2 -270V 0

3 -230 V 0

4 -210 V 0

Darkest 5 -190 V 0

Exposure Lamp

Change

2-9

OPTICS 3 April 1998

4. VL Correction

The light intensity may decrease because of dust accumulated on the optics parts. Additionally, the drum sensitivity gradually decreases during the drum’s life. This may cause dirty background on copies. This is automatically compensated for by the VL correction.

The exposure lamp voltage is increased by +1.0 volts (230-V machines), or +0.5 volts (120-V machines) at the set copy count interval. The VL correction counter tracks the copy count interval. Note that if the VL counter is cleared, an improper correction will be applied. The table below shows the relationship between the SP setting and the interval.

SP63 Setting Exposure Lamp Voltage Special UP31

0 +1 step/4000 copies 0

1 +1 step/3000 copies 1 2 +1 step/2500 copies 2 3 +1 step/2000 copies 3 4 +1 step/1500 copies 4 5 +1 step/1000 copies 5 6 +1 step/500 copies 7 +1 step/250 copies 8 No Correction -

(Special UP Modes)

There are thirteen user program modes on this model (refer to the operator’s manual and UP mode and SP mode cross-reference table). The operator’s manual, however, explains only eight modes of them. The UP modes numbered from 30 to 34 are special UP modes. If it is necessary to change any settings related to the special UP modes, the service representative may ask the user to change it and thus avoid a visit.

Please note that UP31 accepts settings only from 0 to 5.

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3 April 1998 OPTICS

(VL Switch)

Depending on the environment, the default automatic VL correction may not be enough to correct the image density. The VL switch is located on the upper registration roller assembly in the machine and allows the operator to correct image density manually.

The exposure lamp voltage is increased according to the VL switch position.

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Detailed

Descriptions

Position 0 Position 1 Position 2

+10 steps +20 steps

The amount of increase in each position can be changed by SP62 as shown below:

SP62 Setting Special UP Mode Exposure Lamp Voltage

UP32 SW Position 0 SW Position 1 SW Position 2

0 0 0 +10 steps +20 steps

1 1 0 +5 steps +10 steps 2 2 0 +15 steps +30 steps 3 3 0 +20 steps +40 steps

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ERASE 3 April 1998

2.4 ERASE

2.4.1 OVERVIEW

[A]

A227D508.WMF

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The erase lamp [A], which is installed in the upper unit, consists of a single row of LEDs extended across the full width of the drum. The erase lamp has the following functions:

•

Leading edge erase

•

Side erase (A227 machines only)

•

Trail edge erase

A227D509.WMF

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3 April 1998 ERASE

2.4.2 LEAD EDGE ERASE

The entire line of LEDs turns on when the main motor turns on. They stay on until the erase margin slightly overlaps the lead edge of the original image area on the drum (Lead Edge Erase Margin). This prevents the shadow of the original edge from being developed on the copy. At this point, side erase starts (A227 machines only). The width of the leading erase margin can be adjusted using SP41.

2.4.3 SIDE ERASE (A227 MACHINES ONLY)

Based on the reproduction ratio, the LEDs turn on blocks (labeled “a” to “h” on the previous page). This reduces toner consumption and drum cleaning load.

The CPU determines which blocks to turn on based on the selected reproduction ratio as follows.

Reproduction Ratio (%) Blocks ON

70 to 72 a - g 73 to 76 a - f 77 to 80 a - e 81 to 85 a - d 86 to 88 a - c 89 to 92 a - b 93 to 97 a

98 to 100 All Off

2.4.4 TRAILING EDGE ERASE

This minimizes toner consumption.

Detailed

Descriptions

The entire line of LEDs turns on after the trailing edge of the latent image has passed 10 mm from the erase lamp. The length of the latent image is determined by the paper length, which is checked by the registration sensor. The LEDs stay on to erase the leading edge of the latent image in the next copy cycle. After the final copy, the erase lamps and the main motor turn off at the same time.

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DEVELOPMENT 3 April 1998

2.5 DEVELOPMENT

[C]

2.5.1 OVERVIEW

[D]

[B]

[A]

The development unit is contained in the CTDM (Cleaning Toner Development Magazine).

When the main motor turns on, th e development roller [A] and agitator [ B] start turning.

There are permanent magnets in the development roller which attract the developer to the roller. The turning sleeve of the development roller carries the developer past the doctor blade, which trims the developer to the desired thickness.

The development roller sleeve continues to turn, carrying the developer to the drum [C]. When the developer brush contacts the drum surface, the negatively charged areas of the drum surface attract and hold the positively charged toner. In this way, the latent image is developed. The amount of toner consumed during development is supplied from the toner bottle automatically.

The development roller is given a suitable negative bias to prevent toner from being attracted to the non-image areas, which may have a residual negative charge. The bias also controls image density.

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The toner end sensor [D] detects when toner in the CTDM has run out.

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3 April 1998 DEVELOPMENT

2.5.2 TONER SUPPLY MECHANISM

[C]

[A]

[D]

[B]

A227D511.WMF

Before the two seals [A, B] and are removed from a new CTDM, the developer is divided into six cells to prevent developer in it from biasing during shipment. Toner and developer mix when the seals are removed. Whenever a new CTDM is installed into the machine, CTDM initialization must be performed to mix the toner and developer evenly, and create the triboel ectric charge. CTDM initialization is performed at the following times:

•

when the main switch is turned off and on at the toner end condition

•

when the upper cover is opened and closed at the toner end condition

•

SP12 is performed

Detailed

Descriptions

NOTE:

CTDM initialization must be performed by using SP12 if the CTDM is replaced when the toner end condition does not exist.

The developer case is full of developer and toner after CTDM initialization. Toner density in the developer case [C] is kept uniform all the time since the amount of consumed toner is supplied from the toner case [D] automatically.

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DEVELOPMENT 3 April 1998

2.5.3 DEVELOMENT BIAS FOR IMAGE DENSITY CONTROL

Image density is controlled by changing two items—the amount of bias voltage applied to the development roller sleeve, and the amount of voltage applied to the exposure lamp.

Applying a bias voltage to the development sleeve reduces the potential between the development roller and the drum, thereby reducing the amount of toner transferred. As the bias voltage becomes greater, the copy becomes lighter.

The method of control depends on whether the image density is manually selected or auto image density is used.

Base Bias Voltage in Each Image Density Mode

The base bias voltage for non-image areas (between copies) is fixed at -150 Volts. This value is also be compensated by the factors explained later.

The base bias voltage for image areas is determined according to the setting of the image density mode. The following table shows the base development bias. The exposure lamp base voltage correction value is included as a reference.

Photo Mode Darker ADS Lighter

Base Bias -230 V -150 V -150 V -190 V

Exposure Lamp Voltage 0 -6 steps 0 +6 steps

Compensation Factors

1. Automatic Image Density (ADS) Mode

In ADS mode, the exposure lamp base voltage is fixed at a value that is determined by SP48 (see Optics section). Image density is controlled by changing only the development bias voltage.

The bias voltage for ADS mode depends on the background image density of the original as measured by the ADS sensor.

The CPU checks the voltage output from the automatic ID circuit. This circuit has a peak hold function. The peak hold voltage corresponds to the maximum reflectivity of the original. The CPU then determines the proper development bias level with reference to the peak hold voltage.

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3 April 1998 DEVELOPMENT

The table below shows the ratio of the ADS voltage (actual original background density) to the ADS reference voltage (standard white background density) and the development bias voltage.

ADS Voltage Ratio (%) Development Bias Voltage

80 to 100 (light) -150 V

73 to 79 -190 V 60 to 72 -230 V 30 to 59 -270 V

0 to 29 (dark) -290 V

2. Image Density Adjustment Setting (SP34)

Based on SP34, compensation will be applied to the development base bias voltage as shown in the following table. This compensation is applied to all the image density adjustment positions.

SP34 (This can also be changed by UP1)

SP34 Setting Setting Development

Bias Change

0Normal +0 V 0

1 Light -40 V 0 2 Dark +40 V 0 3 Lighter -40 V +3 steps 4 Darker +40 V -3 steps 5 Lightest -40 V +7 steps 6 Darkest +40 V -7 steps

NOTE:

The value in the list will be added to the base bias voltage.

Exposure Lamp Voltage Change

Example) Operation panel set to “Darker” Base bias voltage = -150 Volts SP34 Setting = 3 Development bias = -150 + (-40) = -190 Volts

Detailed

Descriptions

3. Image Density Adjustment at Lighter Setting Position (SP36)

SP36 can change the base bias voltage when the “Lighter” position is selected on the operation panel.

SP36 (This can also be changed by UP3)

SP36 Setting Image Density Base Bias Voltage at Lighter Position

0 Normal -190 V

1 Lighter -230 V 2 Lightes t -270 V

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