Ricoh VT1800 User manual

N810-II
SERVICE MANUAL

INTRODUCTION
This manual explains only the features of the N810-II (C225 model) that are
different compared with the N810 (C217 model). So, please refer to the N810
service manual for the sections which are not described in this manual.

SECTION 1
OVERALL MACHINE
INFORMATION

1. SPECIFICATIONS
Configuration: Desk top
Master Making Process: Digital
Printing Process: Full automatic one-drum stencil system
Image Mode: Line/Photo
Original Type: Sheet
Original Weight: 64 g/m2∼104.7 g/m2(17.0 lb ∼27.9 lb)
Original Size: Max: 216 mm x 356 mm (81/2" x 14")
(Legal Drum)
216 mm x 297 mm (81/2" x 11.7")
(A4 Drum)
Min: 90 mm x 140 mm (31/2" x 51/2")
Paper Size: Max: 216 mm x 356 mm (81/2" x 14")
(Legal Drum)
216 mm x 297 mm (81/2" x 11.7")
(A4 Drum)
Min: 90 mm x 140 mm (31/2" x 51/2")
Paper Weight: 52 g/m2∼150 g/m2(13.8 lb ∼39.9 lb)
Printing Area: LG drum: 210 mm x 349.6 mm
(8.3" x 13.8") or less
A4 drum: 210 mm x 291 mm
(8.3" x 11.5") or less
Printing Speed: 70/100/130 cpm (3 settings)
First Copy Time: 28 seconds ± 2 seconds (Legal Drum)
26 seconds ±2 seconds (A4 Drum)
Second Copy Time: 30 seconds ±2 seconds (Legal Drum)
28 seconds ±2 seconds (A4 Drum)
Leading Edge Margin: 5mm ±3 mm (0.2" ±0.12")
5 September 1995 SPECIFICATIONS
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Trailing Edge Margin: 1 mm ±1 mm (0.04" ±0.04")
Paper Feed Table Capacity: 500 sheets (80 g/m2, 20.0 lb)
Paper Delivery Table Capacity: 500 sheets (80 g/m2, 20.0 lb)
Master Eject Box Capacity: More than 25 masters
ADF Original Capacity: 6 sheets or a 0.6 mm height
Weight: 55 kg (122 lb)
Power Source: 120 V, 60 Hz, more than 3.6 A (for North
America)
220 V ∼240 V, 50/60 Hz, more than 2.1 A
(for Europe, Asia)
Power Consumption: Master Making: Less than 0.22 kW
Printing: Less than 0.22 kW
Dimensions:
(W x D x H) [Tables stored] 692 mm x 612 mm x 440 mm
(26.2" x 24.1" x 17.3")
[Tables set up]
1050 mm x 612 mm x 440 mm
(41.3" x 24.1" x 17.3")
Pixel Density: 300 dpi
Print Counter: 7 digits
Master Counter: 6 digits
Noise Emission:
Printing Speed Operator position Bystander position
70 rpm less than 66 dB less than 64 dB
100 rpm less than 70 dB less than 68 dB
130 rpm less than 72 dB less than 71 dB
The measurements are to be made in accordance with ISO 7779.
SPECIFICATIONS 5 September 1995
1-2

Optional Equipment: Key Counter, Tape Dispenser
Consumables:
Name Size Remarks
Thermal master Length: 125 m (410 ft)/roll
Width: 240 mm (9.5") 260 masters can be made per roll with a Legal Drum.
304 masters can be made per roll
with an A4 Drum.
Storage Conditions:
–10 ∼40°C, 10 ∼90% RH
Ink 600 cc/pack Storage Conditions:
–5 ∼40°C, 10 ∼90% RH
Tape for tape maker 35 m (114.8 ft)/roll
5 September 1995 SPECIFICATIONS
1-3

2. ESSENTIAL DIFFERENCES BETWEEN THE
C217 AND THE C225
No. Item Remarks
1 Paper Delivery System The paper delivery system has been changed from a
delivery roller system to a vacuum transport system. Due
to this modification, 5 mm side margins are not required
for originals.
2 Paper Table Set Switch A magnetic switch has been added to detect whether or
not the paper table is in the paper feed position. Indicator
"B" lights when the paper table is in the low position.
3 Thermal Head To minimize ink set-off, the shape of the thermal head
heating elements have been changed as shown below.
4 Paper Table Side
Fences For easy side fence positioning, a rack and pinion mechanism has been installed. The left and right side
fences move together.
5 Master Eject Box To prevent the used master from drooping when the
customer takes out the master eject box, a master holder
has been added to the master eject box.
6 Paper Delivery Table The delivery end fence and the side fences can be folded
for storing in the delivery table.
7 Master Eject Box
Capacity The pressure for compacting the master in the master eject box has been increased. The master eject box
capacity has been increased from 15 to 25 masters.
8 Economy Mode If Economy mode is selected, the thermal head energy is
reduced by 15% (this is done by changing the pulse
width). The image density will be slightly lighter, and ink
consumption will be less than normal.
C225V500.img
ESSENTIAL DIFFERENCES BETWEEN THE C217 AND THE C225 5 September 1995
1-4

No. Item Remarks
9 Exposure Glass Bracket To prevent the scanned original from being pushed out by
the next original, the shape of the exposure glass bracket
has been changed as shown below.
10 Original Feed Spring
Plate To ensure proper feeding of thin paper, the angle of the original feed spring plate has been changed.
11 Paper Feed Timing To reduce noise which occurs when the paper hits the
2nd feed roller, the first paper feed length has been
reduced. (The buckle between the 1st and 2nd paper
feed rollers has been shortened.)
12 Skip Feed A user can select from 2 to 9 rotations of the drum while
one sheet of paper is fed.
13 A4 Size Drum (Only A4
machines) To minimize master consumption, the screen mesh length and the master cut length of the Europe/Asia machines
has been shortened. (The master consumption of the
LT/LG machines is the same as for the C217.)
14 Quality Start The first print tends to be light. To increase the image
density of the first print, Quality Start mode can be
selected. In this mode, the first print is made at 30 rpm.
15 Image Processing in
the "Darker 2" setting In the C217 model, only the A/D conversion parameters are changed when the image density setting is changed.
This does not change the density of solid black areas.
In the C225 model, if "Darker 2" is selected on the
operation panel, the thermal head energy is increased to
115% of the normal setting. The solid black areas will
become darker.
H225V501.wmf
5 September 1995 ESSENTIAL DIFFERENCES BETWEEN THE C217 AND THE C225
1-5

3. PRINTING PROCESS
1. Master Ejecting: The machine ejects the used master
wrapped around the drum into the master
eject box.
2. Scanning: The machine scans the original using the
CCD, through the mirror and the lens,
while feeding the original.
3. Master Feeding: The machine converts the signal from the
CCD into digital signals and sends them to
the thermal head to make holes in the
master. The master then wraps around
the drum.
4. Paper Feeding: The machine sends paper separately to
the drum.
5. Printing: The machine presses the paper fed from
the paper feed section against the drum.
This transfers the ink to the paper through
the drum screen and the master.
6. Paper Delivering: The machine peels off the printed paper
with the exit pawls and air knife, and
ejects the paper onto the paper delivery
table.
1
2
3
4
5
6
C225V502.img
PRINTING PROCESS 5 September 1995
1-6

4. MECHANICAL COMPONENT LAYOUT
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C225V502-2.img
1. Mirror
2. Original Feed Roller
3. Original Pressure Plate
4. Exposure Lamp
5. Exposure Glass
6. Original Pick-up Roller
7. Original Friction Pad
8. Master Tension Roller
9. Platen Roller
10. Thermal Head
11. Master Roll
12. Platter Unit
13. Ink Pump
14. Paper Table
15. Paper Feed Roller
16. Friction Pad
17. 2nd Feed Roller
18. Doctor Roller
19. Press Roller
20. Ink Roller
21. Exit Pawl
22. Transport Unit
23. Paper Delivery Table
24. Drum
25. Master Eject Box
26. Master Eject Roller
27. CCD Unit
28. Original Exit Tray
29. Master Eject Unit
5 September 1995 MECHANICAL COMPONENT LAYOUT
1-7

5. DRIVE LAYOUT
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C225V503.img
1. Pump Drive Gear
2. Ink Supply Motor
3. Platen Roller Gear
4. Original Feed Motor
5. Original Pick-up Roller
6. Original Feed Roller
7. Drum Drive Gear
8. Upper Master Eject Roller Gear
9. Lower Master Eject Roller Gear
10. Master Eject Motor
11. Master Clamper Motor
12. Master Clamper Drive Gear
13. Transport Unit Drive Pulley
14. 2nd Feed Motor
15. Main Motor
16. 2nd Feed Roller Gear
17. Paper Feed Roller Gear
18. Master Feed Motor
DRIVE LAYOUT 5 September 1995
1-8

6. ELECTRICAL COMPONENT DESCRIPTION
Index No. Name Function
Motors
11 Master Feed Feeds the master to the drum.
25 Master Eject Sends the used master into the master eject
box.
28 Main Drives the paper feed, drum, printing and
paper delivery unit components.
29 Vacuum Provides suction so paper is held firmly on
the transport belt.
32 2nd Feed Drives the 2nd feed roller.
35 Master Clamper Open and closes the master clamper.
38 Air Knife Rotates the fan which generates the air knife
to separate the paper from the drum.
40 Pressure Plate Drives the pressure plate.
45 Original Feed Transports the original for scanning.
46 Master Cutter Cuts the master.
49 Ink Supply Drives the ink pump to supply ink.
Solenoid
31 Pressure Release
Solenoid Releases the press roller to apply printing pressure.
Sensors
1 Master End Detects if the plotter unit has run out of
master roll.
3 Original Registration
(Upper: light receiver,
Lower: light emitter)
Informs the CPU of the original position.
Also, detects original misfeed.
14 Feed Jam Timing Determines the paper misfeed check timing.
15 Paper End Detects if there is any paper on the paper
table.
16 Registration Detects paper misfeeds.
17 Feed Start Timing Determines the paper feed start timing.
18 Exit Jam Timing Determines the master misfeed check timing.
19 Master Eject Position Detects the master eject position of the drum.
26 Drum Master Detects if there is a master on the drum.
30 Exit Detects paper misfeeds.
33 Master Eject Detects used master misfeeds.
37 Full Master Detects if the master eject box is full.
39 Pressure Plate H.P. Detects the pressure plate home position.
48 Original Set Detects if there is an original on the original
table.
Switches
5 ADF Open Checks if the ADF is open.
6 Left Cutter Determines the left limit position of the cutter.
9 Master Cut Starts the cutter motor to cut the master.
13 Paper Table Set Detects if the paper table is in the paper feed
position.
5 September 1995 ELECTRICAL COMPONENT DESCRIPTION
1-9

Index No. Name Function
21 Scanner Unit Open Checks if the scanner unit is open.
22 Delivery Cover Open Checks if the delivery cover is open.
23 Main Turns the power on or off.
27 Master Eject Box Checks if the master eject box is set
correctly.
36 Master Clamper Detects the master clamper open/close
position.
47 Right Cutter Determines the right limit position of the
cutter.
Printed Circuit Board
4 Lamp Control Controls the power to the exposure lamp.
8 Operation Panel Interfaces the CPU with the operator.
12 Main Controls all machine functions.
20 Power Supply Provides power for all dc components.
24 Main Motor Control Controls the main motor speed.
34 Noise Filter Filters out electrical noise on the ac power
input lines.
41 CCD Converts light intensity into an electrical
signal.
42 A/D Conversion Converts the analog signals into digital
signals.
Counters
7 Print Keeps track of the total number of prints
made.
10 Master Keeps track of the total number of masters
made.
Others
2 Thermal Head Makes the master using heat.
43 Paper Feed Clutch Transmits main motor drive to the paper feed
roller at the appropriate time.
44 Exposure Lamp Illuminates the original for exposure.
ELECTRICAL COMPONENT DESCRIPTION 5 September 1995
1-10

SECTION 2
DETAILED SECTION
DESCRIPTIONS

1. PAPER FEED
1.1 PAPER TABLE
The paper table side fences [A] should be adjusted depending on the paper
size. The left and right side fences move together because of the rack and
pinion [B], to ensure correct paper positioning on the tray. If the dial [C] is
turned, the side fences move together, changing the paper position on the
table.
When the lever [D] is lowered and the paper table is in the no-paper feed
position, the magnetic switch [E] is de-activated. In this condition, the Print
Start key is disabled.
[A]
[B]
[D]
[E]
[C]
C225D506.wmf
5 September 1995 PAPER FEED
2-1

2. PAPER DELIVERY SECTION
2.1 OVERALL
The exit pawl [A] and the air knife [B] separate the paper from the drum. The
paper is transported to the delivery table by the transport unit [C].
There is a reflective photosensor [D] to detect paper jams.
[B] [A]
[D]
[C]
C225D505.img
PAPER DELIVERY SECTION 5 September 1995
2-2

2.2 VACUUM UNIT DRIVE MECHANISM
The vacuum fan [A] holds the paper against the transport belts [B] to deliver
the paper to the delivery table. The transport belts are driven by the main
motor through gears [C].
The exit sensor (reflective photosensor) [D] located on the vacuum unit
detects paper jams.
[B]
[A]
[C]
[D]
C225D507.wmf
5 September 1995 PAPER DELIVERY SECTION
2-3

3. IMAGE PROCESSING
3.1 IMAGE DENSITY SETTING
The A/D conversion parameters (refer to page 2-43 of the C217 model
service manual) and thermal head energy change depending on the image
density selected on the operation panel.
The table below shows the relationships between the image modes,
parameters, and the thermal head energy.
VH (%) M1 (%) M2 (%) M3 (%) VL (%) T/H
Energy
(%)
Shading Distortion Memory 100 86.5 73.0 59.5 46.0
Image
Setting Line Mode Lighter 74.0 57.0 40.0 23.0 6.0 100
Normal 100 76.5 53.0 29.5 6.0 100
Darker 1 100 79.8 59.5 39.3 19.0 100
Darker 2 100 79.8 59.5 39.3 19.0 115
Photo
Mode Lighter 70.0 36.6 19.6 11.4 7.0 100
Normal 80.0 43.4 24.8 15.8 11.0 100
Darker 1 85.0 47.9 29.0 19.9 15.0 100
Darker 2 85.0 47.9 29.0 19.9 15.0 115
In the C217 model, the thermal head energy is always the same regardless
of the image density setting. Only the A/D conversion parameters change
depending on the selected image density. Using this method, the image
density of solid black areas does not change even if a darker setting is
selected. This is because all the pixel data will be the same (evenly black)
after the binary processing, if the area is purely black.
In the C225 model, when Darker 2 is selected, the A/D conversion
parameters are the same as those of Darker 1, but the thermal head energy
increases to 115% of the normal thermal head energy. (This is done by
changing the pulse width.) As a result, the density of solid black areas will
become darker.
IMAGE PROCESSING 5 September 1995
2-4

4. MASTER PLOTTING AND PRINTING AREA
1. Length (Legal Drum)
Original
Master
Screen
Paper
(Shift : 0 mm)
Paper
(Shift : –15 mm)
Paper
(Shift : 15 mm)
C225D502.wmf
5 September 1995 MASTER PLOTTING AND PRINTING AREA
2-5

(A4 Drum)
Original
Master
Screen
Paper
(Shift : 0 mm)
Paper
(Shift : –15 mm)
Paper
(Shift : 15 mm)
C225D503.wmf
MASTER PLOTTING AND PRINTING AREA 5 September 1995
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