Ricoh FT1008/208 Service Manual Scrn

FT1008/FT1208

(PLOVER, A226/A227)

SERVICE MANUAL

(SCREEN VERSION)

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.

April 8, 1998 Specifications

OVERALL MACHINE INFORMATION

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

April 8, 1998 Specifications

Reproduction Ratios:

Enlargement 141%

Full Size 100% 100%

Reduction 82%

Metric Version Inch Version

141%

122%

93%

71%

78% 70%

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

April 8, 1998 Specifications

Toner Replenishment: CTDM exchange (140g/CTDM) Copy Tray Capacity: 50 sheets 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

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 Less than 55 dB Sound power level in stand-by condition Less than 40 dB Sound power level during copy cycle Less than 62 dB

The measurements were made according to ISO 7779

(120 V machines/230 V machines)

April 8, 1998 Specifications

Weight: Less than 16.5 kg, 36.4 lb Energy Star Enabled by SP77—default is ON)

Sleep time selected by SP14—default is 30 minutes

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

green). To restore operation, press any key other than the Start key.)

April 8, 1998 COPY PROCESSES AROUND THE DRUM

COPY PROCESSES AROUND THE DRUM

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 tha t will not b e used for the copy image. The resistance of the drum in the illuminated areas drops and the charge on those areas dissipates.

April 8, 1998 COPY PROCESSES AROUND THE DRUM

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 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.

April 8, 1998 MECHANICAL COMPONENT LAYOUT

MECHANICAL COMPONENT LAYOUT

3 4 5 6

8 9

141516

April 8, 1998 MECHANICAL COMPONENT LAYOUT

1. 2

mirror

9. Development roller

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

April 8, 1998 ELECTRICAL COMPONENT LAYOUT

ELECTRICAL COMPONENT LAYOUT

April 8, 1998 ELECTRICAL COMPONENT LAYOUT

April 8, 1998 ELECTRICAL COMPONENT DESCRIPTIONS

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 Drives all the main unit components

except for the optics unit and fans.

M2 Exhaust Fan Motor Removes heat from around the fusing

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

(A227 machines only)

Clutches

CL1 Paper Feed clutch Transfers main motor drive to the

Switches

SW1 Interlock Switch Cuts all power when the upper unit is SW2 VL Switch Changes the light intensity of exposure

Moves the lens and 4th/5th mirror

positions in accordance with the

selected magnification.

paper feed roller.

opened.

lamp.

24 14

April 8, 1998 ELECTRICAL COMPONENT DESCRIPTIONS

Sensors

S1 ADS Sensor Detects the background density of the

original.

S2 Registration Sensor Detects paper end condition. Checks if

paper is set on the by-pass feed table.

S3 Lens and Mirror H. P.

Sensor (A227 machines only)

Informs the CPU when the lens and

th/5th

mirror assembly are at the home

position (full size position).

S4 Scanner H. P. Sensor Informs the CPU when the 1st scanner

is at the home position.

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

Solenoid

SOL1 Registration Solenoid Releases the stopper, synchronizing

the paper-feed timing with the original

scan.

Printed Circuit Boards

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

corona, transfer corona, and

development bias.

PCB3 Power Supply Board Generates 5 Vdc and 24 Vdc outputs

from 120 Vac or 230 Vac inputs. Drives

the exposure lamp, fusing lamp, and

main motor.

13 11

April 8, 1998 ELECTRICAL COMPONENT DESCRIPTIONS

PCB4 Operation Panel Board Informs the CPU of the selected

modes and displays the machine

condition on the panel.

PCB5 Noise Filter Removes electrical noise from the

input power.

Lamps

L1 Exposure Lamp Applies high intensity light to the

original for exposure.

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

the drum surface after cleaning.

L4 Erase Lamp Discharges the drum outside of the

image area. (Provides leading/trailing

edge and side erase.)

Others

TH1 Optics Thermistor Monitors the temperature around the

exposure lamp for overheat protection.

TH2 Fusing Thermistor Monitors the fusing temperature. 26 TF1 Exposure Lamp

Thermofuse

TF2 Fusing Thermofuse Provides back up overheat protection

CO Total Counter Keeps a count of the total copies

Provides back up overheat protection

around the exposure lamp.

in the fusing unit.

made. (option)

16 15

2 19 —

April 8, 1998 DRUM

DETAILED DESCRIPTIONS

DRUM

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.

April 8, 1998 CHARGE

CHARGE

OVERVIEW

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.

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

[A]

[B]

April 8, 1998 CHARGE

EXHAUST FAN AND OZONE FILTER

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]

April 8, 1998 OPTICS

OPTICS

OVERVIEW

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

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

April 8, 1998 OPTICS

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 first scanner provides back up overheat protection. It opens if the temperature reaches 128°C and cuts ac power to the exposure lamp.

April 8, 1998 OPTICS

SCANNER DRIVE

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.

[C]

[F]

[G]

[E]

[A]

[D]

[B]

April 8, 1998 OPTICS

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

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.

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.

[B]

[C]

[D]

[A]

[E]

[F]

April 8, 1998 OPTICS

AUTOMATIC IMAGE DENSITY CONTROL SYSTEM (ADS)

[A]

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” from the leading edge of original in full size mode. These lengths “a” and “b” will vary depending on the selected reproduction ratio.

April 8, 1998 OPTICS

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.

April 8, 1998 OPTICS

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:

128

for 120 V machines (= 64 V)

120

for 230 V machines (= 120 V)

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.

April 8, 1998 OPTICS

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. 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.

April 8, 1998 OPTICS

SP34 (This can also be changed by UP1.)

SP34 Setting Setting Exposure Lamp

Voltage Change

0Normal 0 0

1 Light 0 -40 V 2 Dark 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.)

April 8, 1998 OPTICS

(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

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

April 8, 1998 OPTICS

(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).

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.)

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