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 potential 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.

∙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

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-inclu- sive, 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.

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			:	Plain paper weighing 60 to 90 g/m2
Size of Paper			: A4 crosswise, B5 lengthwise, B5 crosswise, Letter
				crosswise
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

2 PARTS IDENTIFICATION

3 4 5

2

6

1

				7
	9	8	4605M006AA	4605M007AA
				10
1.	LCT Door		6.	Paper Plate Descent Switch S1B
2.	Edge Guide		7.	Front Cover
3.	Top Cover		8.	Relay Cord
4.	Paper Plate		9.	Door Unlocking Lever
5.	Paper Transport Port		10. Rear Cover

M-1

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

4605M008AA

M-2

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 ELECTRICAL COMPONENT LAYOUT

M2

PC2

		PC5
PC3					PWB-B
PC6
					PC1
PWB-A
			S1B
PC4
					M1

H1

PC7

			4605M010AA
Symbol	Name	Symbol	Location
PWB-A	Master Board	PC1	Elevator Pulse Sensor
PWB-B	Paper Plate Descent Switch	PC2	Paper Plate Upper Position
	Board		Sensor
M1	Elevator Motor	PC3	Paper Empty Sensor
M2	Paper Take-Up Motor	PC4	Paper Plate Lower Position
H1	Paper Dehumidifier Heater		Sensor
S1B	Paper Plate Descent Switch	PC5	Paper Take-Up Sensor
		PC6	LCT Set Detecting Sensor
		PC7	LCT Door Open/Close Detecting
			Sensor

M-4

6 MECHANICAL DESCRIPTIONS

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

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

<M1 Turning 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 Upper Position Sensor PC2.

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

- Paper Take-Up Sequence - Sheets of paper are taken up.

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

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

M1 is deenergized.

This sequence of operations is repeated to maintain a given pressure between the paper stack and Paper Take-Up Roll.

- Descent Motion -

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.)

<Control>

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

M1		IC1A
	Pin 42		Pin 43
Forward (Ascent)	H		L
Backward (Descent)	L		H
Stopped	H		H
Braked	L		L

M-6

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

4605M013AA

Paper Feed Roll

Paper Separator Roll

Paper Take-Up 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

1285M013

<Paper Take-Up Control>

∙Rotation of Paper Take-Up Motor M2 is controlled by the pulse signals output from IC2A- 1, 2, 4, and 17 of Master Board PWB-A.

IC2A			Rotation
1		L	L	H	H
2		H	H	L	L
17		L	H	H	L
4		H	L	L	H

M-8