Ricoh FT4430 Service manual

RICOH FT4430

SERVICE MANUAL

RICOH COMPANY, LTD.

SECTION 1

OVERALL MACHINE

INFORMATION

SPECIFICATIONS . . OPERATION PANEL

SECTION A . . . . . . . . .

SECTION B . . . . . . . . .

Table of Contents

SPECIFICATIONS

April ’88

Configuration:

Copying Process:

Original:

Original Size:

Copy Paper Size:

Copy Paper Weight:

Reproduction Ratios:

Enlargement

Full Size

Reduction

Desk top

Dry electrostatic transfer system

Sheet/book

Maximum A3 (11“ x 17”)

Maximum A3 (11“ x 17”) Minimum A6

(51/2" x

81/2”)

Cassette feed 52 to 128 g/m

Manual feed

52 to 157 g/m

See the following table:

A4 Version Letter Version

1:1.41 1:1.55

1:1.22 1:1.15

1:1

●

1:0 93

1:0.82

● . .

1:0.71

1:1.29 1:1.21

1:0 93

●

1:0 77 1:0.74

1:0.65 1:0.65

(14 lb to 34 lb)

(14 lb to 42 lb)

Zoom:

From 65% to 155% in 1 % steps

Reproduction Ratio Full size - Enlargement or

Change:

Full size - Reduction in less than 5 seconds

Enlargement

- Reduction or

Reduction - Enlargement in less than 6.5

seconds

16 April ’88

Copying Speed:

The copy speed (in copies per minute) is shown

in the following tables:

A4 Version

A3 B4 A4 B5

20 20

A4R B5R

15 15

Letter Version

LDG LG LT LT(R)

12 15

When used with document feeder, A4 (LT) speed is 17 cpm (sideways).

First-Copy Time:

6.0 seconds (A4 or

81/2” x 11”)

Warm-Up Time: Approximately 100 seconds (23°C)

Copy Number Input:

Special Functions:

Numeral keys, 1 to 999, (count up or count down)

- Margin adjustment

- Auto size magnification mode

-2 single copies mode

- Auto paper select and auto reduce/eniarge mode (with ADF only)

Manual Image Density

7 Steps (Development bias variable)

Selection:

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

or no auto reset. All functions canceled except cassette selection.

Quantity entered returns to “1”, and reproduction ratio returns to full size.

1-2

16 April ’88

Paper Feed:

- Double universal cassette feed, 250 sheets each (auto cassette shift)

- Manual feed table

- Optional large capacity tray (LCT) at second

feed station.

Paper-Feed System: Friction-pad system

Exposure System: Slit exposure, moving optics

Lens:

Through lens, F8, f = 180mm

Light Source: Halogen lamp (85 V, 290 W)

Photoconductor:

Charge System:

Erase:

Selenium drum (F type)

Dual wire dc corona

LED lamp unit (34 LEDs)

Development System: Magnetic brush roller

Toner Density Control:

Development Bias System:

Automatic, direct density sensing

Automatic voltage change (The control board monitors the selected image density level, drum temperature, and rest time.)

Toner Replenishment:

Toner Consumption:

Cleaning System:

Cartridge exchange (300 g/cartridge)

Approx. 7,500 copies/cartridge (A47% original)

Blade and brush

Quenching System: Photo-quenching

Image Transfer:

Paper Separation:

Single wire dc corona, pre-transfer lamp

Dual wire ac corona and pick-off pawls

Image Fusing:

Heat/pressure - roller type

Fusing Lamp: Halogen lamp (840 W)

1-3

16 April ’88

Electronic Control

8-bit microprocessor

System:

Copy Tray Capacity:

250 sheets (B4 / 10” x 14”)

100 sheets (A3 / 11” x 17“)

Self-diagnostics:

19 codes, displayed in the copy counter

Power Source: 110V/60Hz....15A

115V/60Hz....15A

220V/50Hz....8A

220V/60Hz....8A

240V/50HZ....8A

Power Consumption: Warm-up:

1.0 kW Stand-by: 0.08 kW Copying: 0.42 kW (A4 sideways)

Dimensions:

Maximum:

Copier only:

1.22 kW

(WxDxH)

734 x 654 x 390 mm

28.9 x 25.8 x 15.4 inches

Full System:

1363 x 654 x 460 mm

53.7 x 25.7 x 14.1 inches

Weight:

65 kg (143 lb) (Copier only)

100 kg (221 lb) (Full System Without table)

Optional Equipment: Document Feeder

Sorter (20 bins) Large Capacity Tray Editor Board (requires editing eraser lamp) Color Development Unit (Red, Blue, Green)

1-4

OPERATION PANEL

(A4/A3 Version)

16 April ’88

SECTION A

1. Sort Indicator

2. Stack Indicator

3. Auto Reduce/Enlarge Indicator

4. Auto Paper Select Indicator

5.2 Single Copies Indicator

6. Left Margin Adjustment Indicator

7. Right Margin Adjustment Indicator

8. Original Image Size Indicator

9. Copy Image Size Indicator

10. Zoom Keys

11. Size Magnification Key

12. Margin Adjustment Key

13.2 Single Copies Key

14. Auto Selection Key

15. Sorter Key

1-5

16 April ’88

SECTION B

1. (LT/LDG Version)

(A4/A3 Version)

2 3 4 5 6

7 8 9

14,

15. 16 17 18

●

. ,

●

Auto Image Density Key Manual Image Density Key Manual Image Density Indicator Color Toner Indicator Misfeed Location Display Select Cassette Key

Paper Size Indicator

(

Full Size Key

Full Size Indicator

Magnification Ratio Indicator

Enlarge Key

Reduce Key

16 April ’88

(LT/LDG Version)

1. Number Keys

2. Recall/Enter Key

3. Interrupt Indicator

4. Interrupt Key

(A4/A3 Version)

5. Clear Modes Key

6. Start Key

7. Clear/Stop Key

16 April ’88

PAPER PATH

Paper feed starts from one of the two paper feed stations. The path followed depends on which cassette the operator has selected. For copy processing, all sheets follow the same path from the paper feed mechanism through the fusing unit. After that, copies are delivered to the receiving tray.

1. Paper Feed A friction pad and feed roller mechanism separates one sheet of paper from

the

paper stack and feeds it to the registration rollers. The registration rollers

are not turning at this time. The paper buckles slightly when the leading edge

reaches the registration rollers. Buckling seats the sheet securely between the registration rollers and corrects skew.

1-10

16 April ’88

2. Registration

At the programmed time, the registration rollers start turning to feed the paper to the drum.

Image Transfer

The toner image on the drum surface

is pulled from the drum onto the

passing paper by the transfer corona.

4. Paper Separation

The separation corona breaks the electrostatic attraction between the paper

and the drum. The suction of the vacuum fan pulls the paper onto the transport belt. The transport belt moves the paper with the developed copy

image to the fusing unit.

5. Fusing

The paper passes between two rollers which bond the toner image to the paper by applying heat and pressure. At this point the copy is complete.

1-11

16 April ’88

MECHANICAL COMPONENT LAYOUT

678 9

10 11

Quenching Lamp Main Corona Unit

8 9

Erase Lamp Unit

Toner Shield Glass

(

Fourth Mirror

Toner Cartridge

Development Unit First Feed Roller First Cassette Second Feed Roller Pick-up Roller (LCT) Registration Roller

Pre-Transfer Lamp (PTL) /lmaqe

Density Sensor Board

20. Transfer/Separation Corona Unit

21. Selenium Drum

22. Transport Belt

, 23. Fusing Unit

1-12

DRIVE LAYOUT

16 April ’88

Gears

Second Feed Clutch Gear Pick-up Roller Drive Gear(LCT)

First Feed Clutch Gear

Toner Supply Clutch Gear

Hot Roller Drive Gear

Exit Roller Drive Gear

Sprockets

Main Motor Sprocket

Fusing Drive Sprocket

Feed Drive Sprocket

Cleaning Drive Sprocket Toner Collection Bottle

Drive Sprocket

Development Drive Sprocket

Wire Pulleys

WP1 Scanner Drive Pulley WP2 Second Scanner Drive Pulley

Timing Belt

TB1 Drum Drive Belt

Belt

B1 Transport Belt

Belt Pulley

BP1 Drum Drive Pulley

Chains

Cl Main Drive Chain

1-13

16 April ’88

ELECTRICAL COMPONENT LAYOUT

1-14

16 April ’88

1. Main Motor - Ml

2. Lens Drive Motor - M2

3. Lens HP Sensor - S1

4. Quenching Lamp - L1

5. Drum Heater

6. Erase Lamp - L2

7. Pulse Generator Sensor - S2

8. Toner Supply Solenoid - SOL1

9. Color Toner End Sensor - S3

10. Manual Feed Sensor - S4

11. Color Toner Sensors - S5

12. Registration MC - MCI

13. First Paper Feed MC - MC2

14. First Paper End Sensor - S6

15. Second Paper Feed MC - MC3

16. Second Paper End Sensor - S7

17. First Paper Size Sensor - S8

18. Second Paper Size Sensor - S9

19. Registration Sensor - S10

20. Pre Transfer Lamp - L3

27. Lamp Regulator PCB - PCB1

28. Second Scanner Home Position Sensor - S12

29. Total Counter - CO1

30. Second Scanner Motor - M5

31. Scanner Home Position Sensor - S13

32. Front Cover Safety Switch - SW2

33. Door Switch - SW1

34. Main Motor Capacitor - C

35. Main Switch - SW3

36. Relay PCB - PCB2

37. DC Power Supply Unit - PSU

38. Transformer - TR1

39. Fusing Triac - FT

40. Heater Control PCB - PCB5

41. Power Pack - T/S - P1

42. Interface Board - PCB3

43. Cleaning Solenoid - SOL2

44. Pick-off Solenoid - SOL3

21. Vacuum Fan Motor - M3

22. Toner Overflow Sensor - S14

23. Fusing Lamp - L4

24. Oil End Sensor - S15

25. Paper Exit Sensor - S11

26. Exhaust Blower Motor - M4

45. Feed Control PCB - PCB4

46. Main PCB - PCB6

47. Power Pack - C/B - P2

48. Scanner Drive Motor - M6

49. AC Drive Relay - R1

1-15

16 April ’88

ELECTRICAL COMPONENT DESCRIPTIONS

SYMBOL

NAME

Motors

M2 M3

Main Motor

Lens Drive Motor Vacuum Fan Motor

Exhaust Blower Motor

Second Scanner

Motor Scanner Drive Motor

Magnetic Clutches

MC1

MC2

MC3

Registration MC First Paper Feed MC

Second Paper Feed

FUNCTION

Drives all main unit components except otics unit and fans/bIowers. (100Vac)

Positions the lens. (dc stepper) Provides suction so that paper is

held firmly on the transport belt. (100 Vat)

Removes heat from around the fusing unit. (100 Vat)

Positions the second scanner. (dc stepper)

Drives the scanner. (dc stepper)

Drives the registration rollers. Starts paper feed from the first paper

feed station. Starts Paper feed from the second

fe1’

paper eed station.

LOCATION

2 21

12 13

Solenoids

SOL1

SOL2

SOL3

Switches

SW1

SW2

SW3

Sensors

Toner Supply

Solenoid Cleaning Solenoid

Pick-off Solenoid

Door Switch Front Cover Safety

Switch

Main Switch

Lens Home Position Sensor

Pulse Generator

Energizes to supply toner.

Moves the cleaning blade against the drum.

Brings the pick-off pawls into contact with the drum.

Enables the Door Open indicator. Cuts ac power to ac components.

Supplies power to the copier.

Informs the CPU when the lens is at the full size position.

Supplies timing pulses to the main board.

33 32

1-16

16 April ’88

SYMBOL

S10

S11 S12

NAME

Color Toner End Sensor

Manual Feed Sensor

Color Toner Sensors

First Paper End Sensor

Second Paper End Sensor

First Paper Size Sensor

Second Paper Size Sensor

Registration Sensor Paper Exit Sensor Second Scanner

Home Position Sensor

FUNCTION

Detects when it is time to add toner.

Detects when the manual feed table is open.

Detects which color toner development unit is installed.

Informs the CPU when the first cassette runs out of paper.

Informs the CPU when the second cassette runs out of paper.

Determines what size paper is in the

first cassette.

Determines what size paper is in the second cassette.

Misfeed detector and ON/OFF timing. Misfeed detector. Informs the CPU when the second

scanner is at the home position.

LOCATION

10 11

19 25 28

S13

S14

S15

Scanner Home

Position Sensor

Toner Overflow

Sensor Oil End Sensor

Printed Circuit Boards

PCB1 PCB2 Relay PCB

PCB3 Interface PCB

PCB4

PCB5 PCB6

Lamp Regulator PCB

Feed Control PCB

Heater Control PCB Main PCB

Lamps

Quenching Lamp

Erase Lamp

Pre-Transfer Lamp

Informs the CPU when the scanner is at the home position.

Detects when the

full

Detects low

Regulates the exposure lamp voltage.

Main power relay. Provides 100 volts

ac to motors and circuits.

Interfaces the data

copier main board and the sorter and/or DF main boards.

Contains multiplexing circuitry to control feed components.

Controls heater switching. Controls all copier functions both

directly and through other PCBS.

Neutralizes any charge remaining on

the drum surface after cleaning.

Discharges the drum outside of the image area. Provides lead/traiI edge erase and editing functions.

Reduces charge on the drum surface before transfer.

used toner bottle is

oil condition.

between the

27 36

40 46

4 6

1-17

16 April ’88

SYMBOL

Power Packs

Transformer

TR1

Counter

CO1

Relays

NAME

Fusing Lamp

Power Pack - T/S

Power Pack - C/B

Transformer

Total Counter

AC Drive Relay

FUNCTION

Provides heat to the fusing unit.

Provides dc voltage for the transfer and provides ac and dc voltage for separation coronas.

Provides high voltage power for the charge corona and the development roller bias.

Steps down the wall voltage to 100

Vat.

Keeps track of the total number of copies made.

Main Power Relay

LOCATION

Others

c FT

PSU

Main Motor Capacitor Fusing Triac DC Power Supply

Unit

Start capacitor Switches fusing lamp on and off. Rectifies 100 Vac input and outputs

dc voltages.

34 39 37

1-18

AC AND DC POWER DISTRIBUTION

16 April ’88

The ac power supply is filtered then distributed to the fusing lamp and the

main transformer. The transformer supplies 100 volts to the cooling fan, vacuum fan, and the main motor.

The”dc power supply unit receives ac 26, 16, and 10 volts, via fuses, from the main transformer. These voltages are rectified and regulated to 24, 15 and 12, and 5 volts respectively and distributed to the sorter, ADF, and the copier

main board. All supplies have their own ground line.

The main board supplies voltage to all copier electrical components including:

power packs, PCBs, and relays. It also supplies the editor.

The LCT has a separate power supply.

1-19

16 April ’88

OVERALL MACHINE CONTROL

The base copier has two CPUs on the main board that control all machine

operations (the main CPU and the optics CPU).

The main CPU is the main controller of this copier. It monitors the input

signals from sensors and controls the electrical devices through program

mable 1/0 devices. The main board has a RAM (2 kilobytes) for the service program function. A battery backs up the power to this RAM. This CPU con

trols the fusing lamp, via the heater control board, the exposure lamp, via the

lamp regulator, and motors directly from the main board.

The optics CPU controls the servomotor (15 volts) and the stepper motors

(24 volts) for the optics section.

The interface board is connected to the copier main board when the

document feeder and/or sorter are installed.

1-20

OPERATION PANEL CONTROL

16 April ’88

The CPU controls all functions of the operation panel. The CPU sends data to

programmable 1/0 devices which form a multiplexing circuit consisting of 8 scan lines and 17 segment lines, Transistors drive all the scan lines at 12 volts to reduce effects from noise.

The multiplexing circuit lights all displays and monitors all keys of the operation panel. The door switch is also monitored by this circuit and acts like any other operation panel key. The counters are also controlled by the operation panel multiplexing circuit and act like the operation panel lamps.

SECTION 2

DETAILED SECTION

DESCRIPTIONS

OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : . . . . . . ...2-6

LEAD EDGE ERASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-7

SIDE ERASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-7

I. Side Erase Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-8

TRAIL EDGE ERASE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-9

ERASE LAMP CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-10

OPTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . ...2-12

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

SCANNER DRIVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-13

I. Scanner Drive Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-13

2. Scanner Motor Control

LENS/MIRRORPOSITIONING

I. Lens Drive . . . . . . . . . . .

Z. Lens Positioning . . . . . .

3. Second Scanner Drive .

4. Second Scanner Positioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-18

STEPPER MOTOR CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-19

AUTOMATIC IMAGE DENSITY SENSING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-20

EXPOSURE LAMP CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-21

Service Call Conditi.ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-22

DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-23

overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DRIVE MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-24

SEALS AND END MAGNETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-25

CROSS-MIXING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-26

IMAGE DENSITY CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-27

1. ManualImag eDensityControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-27

Z. Automatic Image Density Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-28

. . . . . . . . . . . . ...2-23

3. Bias Compensation Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-29

4. Rest Time Compensation (V2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-29

5. Drum Temperature Compensation (V3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-30

6. Total Bias (VT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-30

BIAS FOR ID SENSING . . . . . . . . . . o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-31

BIAS CONTROL CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-32

COLOR DEVELOPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-33

I. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-33

Z. Bias Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-33

3. Base Bias for Color . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-33

4. Bias for lD Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-33

5. Color Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-34

SERVICE CALL CONDITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-35

TONER DENSITY DETECTION AND TONER SUPPLY . . . . . . . . ...2-36

TONER DENSITY DETECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-36

TONER DENSITY CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-37

TONER SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-39

I. Roller Drive Mechanism.. . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . ...2-39

Z. Toner Agitator Drive Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-40

TONER SUPPLY AMOUNT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-41

l. Detect Supply Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-41

Z. Fixed Supply Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-41

TONER END DETECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-42

COLORTONERDENSITY DETECTIONANDCOLOR TONER SUPPLY . . . . . . . ...2-42

l. Color Toner Density Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-42

Z. Color Toner End Detection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-43

3. Abnormal Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-44

SERVICE CALL CONDITION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-44

IMAGE TRANSFER AND PAPER SEPARATION . . . . . . . . . . . . . ...2-45

PRE-TRANSFER LAMP (PAL).... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-45

IMAGE TRANSFER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-45

PAPER SEPARATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . ...2-46

PRE-TRANSFER LAMP CIRCUIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-47

TRANSFER/SEPARATIONCORONA CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-48

PICK-OFF MECHANISM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-49

l. Touch and Release Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-49

2. Side to Side Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-50

PICK-OFF CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-51

DRUM CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-52

OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...2-52

16 April ’88

DRUM

SELENIUM DRUM

Selenium has the characteristics of:

Being able to accept a high positive electrical charge in the dark. (The electrical resistance of selenium is high in the absence of light.)

Dissipating the electrical charge when exposed to light. (The conductivity of selenium is greatly enhanced by exposure to light.)

Dissipating an amount of charge in direct proportion to the intensity of the

light. That is, where a stronger light illuminates the selenium surface, a smaller voltage remains on the selenium.

The sensitivity of selenium changes slightly with variations in the surface

temperature of the drum. (Under cool conditions, the drum may be

excessively charged; this will result in background or excessive image density.) To prevent this, the CPU monitors the temperature variations around

the drum and changes the development bias accordingly. Also, during cold

periods, the drum heater warms the drum.

Drum sensitivity also depends on how long the drum has rested between copy runs. The copier’s CPU compensates for changes in drum sensitivity due to rest time by changing the development bias. This prevents variations in

image density at the beginning of copy runs The selenium drum used in this model has high sensitivity, good color

reproduction,

and good reproduction of low contrast originals (pencil

originals, etc.)

2-1

16 April ’88

HANDLING THE DRUM

Never touch the drum surface with bare hands.

●

Store the drum in a CooI dry place away from heat.

When cleaning the drum, always wear gloves.

3 4

Prime the drum with setting powder only when installing a new drum.

●

Never expose the drum to light for long periods.

Drum conditioning is necessary after installing a new drum. In addition, it

should be done at the following times:

1 ) When image density is reduced due to over exposure of the drum

2) After cleaning the drum

3) When the drum is lightly scratched.

●

Always keep the drum in the protective sleeve when inserting or pulling the drum out of the copier.

Before inserting or pulling out the drum, pull the cleaning unit out slightly

to avoid scratching the drum on the pick-off pawls.

Return used drums to the distributor according to standard procedure.

DRUM CHARGE

OVERVIEW

16 April ’88

This copier uses

drum. The corona wires generate a corona of positive ions when the charge power pack [P2] applies a high positive voltage. The selenium coating receives a uniform positive charge (750 t 50 volts) as it rotates corona unit [B].

The main motor fan [C] provides a smooth flow of air to the interior of charge corona unit to prevent uneven build-up of positive ions. (An uneven

build up of positive ions could cause uneven image density.)

a dual wire corotron [A] and a highly sensitive selenium

past

the

[cl

2-3

+ 435 hidden pages

Ricoh FT4430 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual

SPECIFICATIONS

OPERATION PANEL

PAPER PATH

MECHANICAL COMPONENT LAYOUT

DRIVE LAYOUT

ELECTRICAL COMPONENT LAYOUT

ELECTRICAL COMPONENT DESCRIPTIONS

AC AND DC POWER DISTRIBUTION

OVERALL MACHINE CONTROL

OPERATION PANEL CONTROL

DRUM

SELENIUM DRUM

DRUM CHARGE

OVERVIEW