Konica Minolta LT-723 User Manual

SERVICE MANUAL

Model

LT-723

FEBRUARY 1999

CSM-LT723

KONICA BUSINESS TECHNOLOGIES, INC.

LT-723

SERVICE MANUAL

FEBRUARY 1999

Used on Konica 7823

IMPORTANT NOTICE

Because of the possible hazards to an inexperienced
person servicing this equipment, as well as the risk of
damage to the equipment, Konica Business Technolo­gies strongly recommends that all servicing be per­formed by Konica-trained service technicians only.

Changes may have been made to this equipment to
improve its performance after this service manual was
printed. Accordingly, Konica Business Technologies,
Inc., makes no representations or warranties, either
expressed or implied, that the information contained in
this service manual is complete or accurate. It is under­stood that the user of this manual must assume all risks
or personal injury and/or damage to the equipment while
servicing the equipment for which this service manual
is intended.

Corporate Publications Department

© 2001, KONICA BUSINESS TECHNOLOGIES, INC.

All rights reserved.

Printed in U.S.A.

CONTENTS

GENERAL, MECHANICAL/ELECTRICAL

1. SPECIFICATIONS ........................................................................................... M-1

2. PARTS IDENTIFICATION ........................ ........................... ........................... .M-1

3. CROSS-SECTIONAL VIEW ............................................................................M-2

4. DRIVE SYSTEM ..............................................................................................M-3

5. ELECTRICAL COMPONENT LAYOUT ...........................................................M-4

6. MECHANICAL DESCRIPTIONS ..................................................................... M-5

6-1. Mechanical Operation and Control of Paper Plate Lifting ........................M-5

6-2. Mechanical Operation and Control of Paper Take-Up, Separation,

and Transport ............................................... ............................ ...............M-7

6-3. Paper Empty Detecting Mechanism .................................. ......................M-9

6-4. Paper Dehumidifier Heater ......................................................................M-10

DIS/REASSEMBLY, ADJUSTMENT

1. DISASSEMBLY ...............................................................................................D-1

2. PAPER WIDTH CONVERSION .......................................................................D-3

3. IMAGE POSITION ADJUSTMENT ..................................................................D-5

MISFEED DETECTION&
MALFUNCTION DETECTION

1. PAPER MISFEED DETECTION ......................................................................T-2

1-1. Misfeed Detection Timing ............................................................. ...........T-2

1-2. Misfeed Troubleshooting Procedures .................... ................ ..................T-2

2. MALFUNCTION DETECTION ......... .............................. .............. ....................T-4

2-1. Malfunction Detection Timing ..................................................................T-4

2-2. Malfunction Troubleshooting Procedures ................................................T-4

i

SAFETY PRECAUTIONS

SAFETY PRECAUTIONS

Installation Environment

Safety considerations usually are directed toward
machine design and the possibility of human error. In
addition, the environment in which a machine is oper­ated must not be overlooked as a potential safety
hazard.

Most electrical equipment is safe when installed in a
normal environment. However, if the environment is
different from what most people consider to be nor­mal, it is conceivable that the combination of the
machine and the room air could present a hazardous
combination. This is because heat (such as from
fusing units) and electrical arcs (which can occur
inside switches) have the ability to ignite flammable
substances, including air.

When installing a machine, check to see if there
is anything nearby which suggests that a poten-

tial hazard might exist. For example, a laboratory

might use organic compounds which, when they
evaporate, make the room air volatile. Potentially dan­gerous conditions might be seen or smelled. The

presence of substances such as cleaners, paint thin­ners, gasoline, alcohol, solvents, explosives, or simi­lar items should be cause for concern.

If conditions such as these exist, take appropriate
action, such as one of the following suggestions.

effect may be caused by altering any aspect of the
machine’s design. Such changes have the potential
of degrading product performance and reducing
safety margins.

For these reasons, installation of any modification not

specifically authorized by Konica Business Machines
U.S.A., Inc., is strictly prohibited.

The following list of prohibited actions is not all-inclu­sive, but demonstrates the intent of this policy.

• Using an extension cord or any unauthorized
power cord adapter.

• Installing any fuse whose rating and physical size
differs from that originally installed.

• Using wire, paper clips, solder, etc., to replace or
eliminate any fuse (including temperature fuses).

• Removing (except for replacement) any air filter.

• Defeating the operation of relays by any means

(such as wedging paper between contacts).

• Causing the machine to operate in a fashion other
than as it was designed.

• Making any change which might have a chance
of defeating built-in safety features.

• Using any unspecified replacement parts.

• Determine that the environment is controlled

(such as through the use of an exhaust hood) so
that an offending substance or its fumes cannot
reach the machine.

• Remove the offending substance.

• Install the machine in a different location.

The specific remedy will vary from site to site, but the
principles remain the same. To avoid the risk of injury
or damage, be alert for changes in the environment
when performing subsequent service on any ma­chine, and take appropriate action.

Unauthorized Modifications

Konica copiers have gained a reputation for being
reliable products. This has been attained by a combi­nation of outstanding design and a knowledgeable
service force.

The design of the copier is extremely important. It is
the design process that determines tolerances and
safety margins for mechanical, electrical, and elec­tronic aspects. It is not reasonable to expect individu­als not involved in product engineering to know what

General Safety Guidelines

This copier has been examined in accordance with
the laws pertaining to various product safety regula­tions prior to leaving the manufacturing facility to
protect the operators and service personnel from
injury. However, as with any operating device, compo­nents will break down through the wear-and-tear of
everyday use, as will additional safety discrepancies
be discovered. For this reason, it is important that the
technician periodically performs safety checks on the
copier to maintain optimum reliability and safety.

The following checks, not all-inclusive, should be
made during each service call:

CAUTION: Avoid injury. Ensure that the copier is
disconnected from its power source before continu­ing.

• Look for sharp edges, burrs, and damage on all
external covers and copier frame.

• Inspect all cover hinges for wear (loose or bro­ken).

• Inspect cables for wear, frays, or pinched areas.

v

SAFETY PRECAUTIONS

• Ensure that the power cord insulation is not dam­aged (no exposed electrical conductors).

• Ensure that the power cord is properly mounted
to the frame by cord clamps.

• Check the continuity from the round lug (GND) of
the power cord to the frame of the copier -- ensure
continuity. An improperly grounded machine can
cause an electrically-charged machine frame.

Safeguards During Service Calls

Confirm that all screws, parts, and wiring which are
removed during maintenance are installed in their
original positions.

• When disconnecting connectors, do not pull the
wiring, particularly on AC line wiring and high
voltage parts.

• Do not route the power cord where it is likely to
be stepped on or crushed.

• Carefully remove all toner and dirt adhering to any
electrical units or electrodes.

• After part replacement or repair work, route the
wiring in such a way that it does not contact any
burrs or sharp edges.

• Do not make any adjustments outside of the
specified range.

Applying Isopropyl Alcohol

Care should be exercised when using isopropyl alco­hol, due to its flammability. When using alcohol to
clean parts, observe the following precautions:

• Remove power from the equipment.

• Use alcohol in small quantities to avoid spillage

or puddling. Any spillage should be cleaned up
with rags and disposed of properly.

• Be sure that there is adequate ventilation.

• Allow a surface which has been in contact with

alcohol to dry for a few minutes to ensure that the
alcohol has evaporated completely before apply­ing power or installing covers.

Summary

It is the responsibility of every technician to use pro­fessional skills when servicing Konica products. There
are no short cuts to high-quality service. Each copier
must be thoroughly inspected with respect to safety
considerations as part of every routine service call.
The operability of the copier, and more importantly,
the safety of those who operate or service the copier,
are directly dependent upon the conscientious effort
of each and every technician.

Remember...when performing service calls, use good
judgement (have a watchful eye) to identify safety
hazards or potential safety hazards that may be pre­sent, and correct these problem areas as they are
identified -- the safety of those who operate the copier
as well as those who service the copier depend on it!

vi

GENERAL,

MECHANICAL/

ELECTRICAL

1 SPECIFICATIONS

Name : LT-723
Type : Cassette type large capacity tray
Installation : Fixed to the copier using a dedicated Base with Slide Rails
Type of Paper :

Size of Paper : A4 crosswise, B5 lengthwise, B5 crosswise, Letter

Capacity : 1,000 sheets
Power Supply : DC5V, DC24V (supplied from the copier)
Power Consumption : 30W or less
Dimensions : 358 (W) x 446 (D) x 289 (H) mm
Weight : 10.7 kg (main body + rails)

Environmental Requirements: Same as the copier

Plain paper weighing 60 to 90 g/m

crosswise

2

2 PARTS IDENTIFICATION

34

2

1

8

9

1. LCT Door

2. Edge Guide

3. Top Cover

4. Paper Plate

5. Paper Transport Port

5

4605M006AA

6

7

10

6. Paper Plate Descent Switch S1B

7. Front Cov er

8. Relay Cord

9. Door Unlocking Lever

10. Rear Cover

M-1

4605M007AA

3 CROSS-SECTIONAL VIEW

Paper Plate Upper Position Sensor PC2

Paper Empty Sensor PC3

LCT Door

Edge Guide

Paper Feed Roll

Paper Separator
Roll

Paper Take-Up Roll

Paper Plate

M-2

4605M008AA

4 DRIVE SYSTEM

A

B

4605M009AA

A : Paper Take-Up Motor M2 : Drives the Paper Take-Up, Feed, and Separator Rolls.
B : Elevator Motor M1 : Moves the Paper Plate up and down.

M-3

5 ELEC TRICAL COMPONENT LAYOUT

M2

PC2

PC6

PWB-A

PC4

Symbol Name Symbol Location

PWB-A
PWB-B

M1
M2
H1
S1B

Master Board
Paper Plate Descent Switch
Board
Elevator Motor
Paper Take-Up Motor
Paper Dehumidifier Heater
Paper Plate Descent Switch

PC3

PC1
PC2

PC3
PC4

PC5
PC6
PC7

PC5

PWB-B

S1B

H1

PC7

Elevator Pulse Sensor
Paper Plate Upper Position
Sensor
Paper Empty Sensor
Paper Plate Lower Position
Sensor
Paper Take-Up Sensor
LCT Set Detecting Sensor
LCT Door Open/Close Detecting
Sensor

M1

4605M010AA

PC1

M-4

6 MECHANICAL DESCRIPTIONS

6-1. Mechanical Operation and Control of Paper Plate Lifting

•

The Paper Plate is moved up and do wn by the chains and gears which are driven by Ele­vator Motor M1.

< M1 Tur ning Forward = Ascent >

Paper Plate Upper Position Sensor PC2

Elevator Motor M1

4605M011AA

< M1 Turning Backward = Descent >

Paper Plate
Lower Position
Sensor PC4

4605M012AA

M-5

<Mechanical Operation>

- Ascent Motion -

The LCT Door is closed.

(LCT Door Open/Close Detecting Sensor PC7 is blocked L.)

Elevator Motor M1 turns forward. (The Paper Plate starts its ascent motion.)

The Paper Plate moves up and the paper stack blocks L Paper Plate

M1 is deenergized. (The Paper Plate completes its ascent motion.)

The Paper Take-Up Roll gradually lowers to eventually unbloc k H PC2.

M1 turns forward to raise the Paper Take-Up Roll, thus blocking L PC2.

✽

This sequence of operations is repeated to maintain a given pressure

between the paper stack and Paper Take-Up Roll.

Paper Plate Descent Switch S1B is actuated or paper runs out.

M1 turns backward. (The Paper Plate starts its descent motion.)

The Paper Plate lowers to block L Paper Plate Lower Position Sensor PC4.

M1 is deenergized. (The Paper Plate completes its descent motion.)

Upper Position Sensor PC2.

- Paper Take-Up Sequence -

Sheets of paper are taken up.

M1 is deenergized.

- Descent Motion -

<Control>

•

M1 is turned forward, backward, stopped, and braked by the signals output from IC1A-42
and 43 on Master Board PWB-A.

M1

Forward (Ascent) H L

Backward (Descent) L H

Stopped H H

Braked L L

IC1A

Pin 42 Pin 43

M-6

6-2. Mechanical Operation and Control of Paper T a ke-Up, Sep-

aration, and Transport

<Paper Take-Up Mechanical Operation>

The Start key is pressed. (The copy cycle is started.)

Paper Take-Up Motor M2 is energized.

Drive from M2 is transmitted via gears and belt.

The Paper Feed, Separator, and Take-Up Rolls turn counterclockwise.

Paper is transported through the LCT.

Paper Take-Up Motor M2

Paper Take-Up Roll

4605M013AA

Paper Feed Roll

Paper Separator Roll

4605M002AA

M-7

<Paper Separation Mechanical Operation>

•

When two or more sheets of paper are taken up by the Paper Take-Up Roll, the paper
separating mechanism prevents the second and subsequent sheets of paper from being
fed together with the first one. The mechanism consists of the Paper Feed Roll, Paper
Separator Roll, and torque limiter.

•

When only one sheet of paper is taken up:
The turning torque of the Paper Feed Roll is transmitted to the Paper Separator Roll via
the sheet of paper being fed in; however, it is greater than the static torque of the Paper
Separator Roll (torque limiter), which causes the Paper Separator Roll to be turned by
the Paper Feed Roll, thus transporting the sheet of paper.

•

When two or more sheets of paper are taken up at the same time:
The coefficient of friction between the first sheet and the second and subsequent sheets
of paper is small and the static torque of the torque limiter keeps the Paper Separator
Roll stationary .This stops the second and subsequent sheets of paper from being fed in,
allowing only the first sheet of paper to be fed in.

- Single-Sheet Feed - - Multiple-Sheet Feed -

1285M012

<Paper Take-Up Control>

•

Rotation of Paper Take-Up Motor M2 is controlled by the pulse signals output from IC2A­1, 2, 4, and 17 of Master Board PWB-A.

IC2A Rotation

1LLHH
2HHL L

17 L H H L

4HL LH

1285M013

M-8