CBW service revA3 - Adam Equipment USA...@Adam Equipment Company 2005 6 4.0 CBW DESCRIPTION The CBW...

@Adam Equipment Company 2005

Adam Equipment

CBW SERIES

SERVICE MANUAL

ADAM EQUIPMENT CO. LTD. p.n. 4331, Rev. A3, January 2005

@Adam Equipment Company 2005 2

CONTENTS

1.0 INTRODUCTION .............................................................................................3 2.0 TROUBLE SHOOTING GUIDE........................................................................3 3.0 ERROR CODES ..............................................................................................5 4.0 CBW DESCRIPTION .......................................................................................6 5.0 CBW CALIBRATION & PARAMETERS (VER.1.2-2.03) ..................................7

5.1 CBW CALIBRATION (VER. 1.2-2.03) ..........................................................7 5.2 CBW PARAMETERS (VER. 1.2-2.03)..........................................................8

6.0 TWO POINT FACTORY CALIBRATION........................................................10 6.1 ADC OUTPUT CHECKING............................................................................11 7.0 LOAD CELL DAMAGE...................................................................................12 8.0 CBW RS-232 INSTALLATION.......................................................................14 9.0 SCHEMATICS ...............................................................................................16


1.0 INTRODUCTION The CBW series of scales are general purpose scales. Refer to the Operators Manual for details of operation. This manual will cover details of calibration and troubleshooting. If you have a problem with the scales that is not directly addressed by this manual then contact your dealer or Adam Equipment for more assistance. In order to supply further assistance we will need the following information:

2.0 TROUBLE SHOOTING GUIDE PROBLEM POSSIBLE CAUSE Display is blank Power Switch faulty or not connected No turn on test Battery not charged or faulty Power supply faulty or incorrect type E6 is displayed Pan not installed Poor connection Load cell damaged Electronics faulty “- - - - - -“appears on display Maximum capacity exceeded Load Cell damaged Electronics is faulty

Name of your company: Contact Name: Contact telephone, e-mail, fax or other methods: Model number of the scales: Serial number: Software revision number (displayed when power is first turned on): Brief description of the problem: Include any recent history of the scale. For example- Has it been working since it’s delivered Water entered Damaged from a fire Electrical Storms in the area Dropped on the floor, etc.


Display is unstable Drafts or air currents Obstruction under pan Sample is moving (animal weighing) Vibrations through table Temperature changed dramatically Electronics faulty or Battery low Weight value incorrect Calibration error, Recalibrate Unit calibrated with inaccurate weight Balance not level Obstruction between sample pan Wrong unit of weight displayed Cannot use Full Capacity Over-load Stops hitting pan support or hitting bottom of load cell Electronics faulty Parameters set incorrectly Load Cell Damaged Not Linear Overload stops hitting too soon Faulty factory calibration Off Centre Loading error Overload Stops not correct Obstruction under pan Battery will not charge Charging circuit failure Battery Failure

Incorrect adapter (below 800 mA) Processor failure


3.0 ERROR CODES ERROR CODE DESCRIPTION POSSIBLE CAUSES �� Initial Zero is greater than

allowed (4% of maximum capacity) when power is turned on or when the [Zero/Enter] key is pressed.

Weight on the pan when turning the scale on. Excessive weight on the pan when zeroing the scale. Improper calibration of the scale. Damaged load cell. Damaged Electronics.

�� Keyboard error. Improper operation of the scale.

�� A/D count is not correct when turning the scale on.

Platform is not installed. Load cell is damaged. Electronics is damaged.

�� Scale is not stable when setting the percentage weighing.

The scale is not stable. Improper operation of the scale.

��or��or��in old versions�

Calibration error. Improper calibration (should be within + 10% of the factory calibration). The old calibration data will be retained until the calibration process is complete.

�� Scale is unstable. There is vibration or draft making the scale unstable. Electronics may be damaged.


4.0 CBW DESCRIPTION The CBW scales have an enclosure with all components mounted within it. To gain access to the components remove the 4 screws securing the cover to the base. The basic unit consists of:

� Base � Load Cell frame � Power switch � Main PCB assembly � Battery � Display PCB assembly � Keypad

All models of CBW are similar except the selection of load cells and the program. The main circuit board is the same as used in the CBC scales. Normally if a problem is found with a circuit board the most cost effective method of solving the problem is to replace the circuit board. Schematics are attached in order to complete the documentation. However it is rare that the problem due to a faulty component on the PCB is traced by a user. The main PCB assembly includes:

� A/D converter (AU1), � Microprocessor (DU1) and � Power supply/battery charger circuits (DU5, T2).


5.0 CBW CALIBRATION & PARAMETERS (VER.1.2-2.03)

5.1 CBW CALIBRATION (VER. 1.2-2.03) The CBW scales calibrate using metric weights and the CBWa scales can calibrate using either metric or pound weights, depending on the weighing unit in use before calibration. To start calibration turn the scale off and then turn it on again. Press the [Tare] and [%] keys together once, during the initial counting from 9 to 0 on the display. The display will show "��". Remove all weight from the pan and then press the [Zero/Enter] key to set the initial zero point when the scale is stable. The display will then show “��” at which point the calibration mass should be placed on the pan. It is best to use a weight close to the full capacity of the scale. Press the [Zero/Enter] key. The display will then show the last mass used. If this is the same as the mass on the pan then this can be used or a different value can be entered. To use this value, press the [Zero/Enter] key when the stable indicator is on. Or if a different value is desired, enter the value using the [�] arrow key to select the flashing digit and the [�] to increment the flashing digit. If value is correct, press the [Zero/Enter] key to accept when the stable indicator is on. Remove the calibration weight as the scale counts back from 9 to 0. If an error message “��” or “��” is shown during calibration, re-check the calibration and repeat, if necessary. If the error cannot be corrected contact your dealer or Adam Equipment for advice.

After calibration the scale should be checked to verify the calibration and linearity is correct. If necessary, repeat the calibration. Note: Ensure that the scale is stable before accepting any weight. To view the ADC Counts press [Zero/Enter] and [%] together. At zero load, it should be 25,000 and at full load, it should be approximately 500,000.

CBWa scales will also have the Lb or Kg (or g) indicator on to show the denomination of the weight requested. If the scale was in pounds before starting calibration the weights requested will be pound values, or if the scale was weighing in kilograms then metric weights will be requested.


5.2 CBW PARAMETERS (VER. 1.2-2.03) The scale has several parameters that allow the user to set the scale to:

Display the weight in other increments of weight to minimise the affects of vibration, wind or other environmental conditions. Control the back light on the display. It may be necessary to turn the backlight off to maximise battery life. Set the Accumulation to Automatic, manual or set the RS-232 interface to continuously print the weight. Set the accumulation to be active when [Print] key is pressed or to be inactive. Set a range for auto zero. Select another weighing unit than the standard. Disable the Limit Warning Beeper. Adjust the ADC Speed.

To set these parameters press the [Func] and [Print] keys at the same time. Setting the scale increment

The display will show "��" where ��can be 1, 2, 5,10 or 20. The first value shown is the default scale increment value.

To change to a different increment value press [Tare/�].

Press the [Zero/Enter] key to store the changed value.

For example, on a 15kg scale the standard increment is 0.5g, the value can be changed to 1.0g or 2.0g.

Control the backlight

The standard is to have the backlight operate automatically, turning it off when the scale is not being used.

The backlight can be set to be "��", "��" (Automatic) or "��". The maximum battery life is achieved with the backlight turned off.

Press the [Tare/�] key to change the setting.

Press the [Zero/Enter] to store the changed setting.

Automatic accumulation

With "��" the memory will accumulate the weight automatically.

"��" will enable the manual accumulation.

"��" will set the RS-232 interface to send the weight continuously and the accumulation function is disabled.


Press the [Tare/�] key to change the setting.

Press the [Zero/Enter] key to store the changed setting.

Accumulation of data in memory when [Print] is pressed

To accumulate weight in the memory when [Print] is pressed, set "��". To use the [Print] key to only print the weight without adding it to memory, set "��".

Press [Tare/�] to change the setting between �� and ��.


Auto zero range

The auto-zero will automatically set the scale to zero when the displayed weight is almost near zero. This helps to make sure that the scale is measuring weight from an accurate zero starting point.

The Auto zero value can be set to 0.5, 1, 2 or 4 scale divisions. The normal setting is 1 scale division. The display will show “��”.

Press the [Tare/�] key to change the value.


Selectable unit of weight displayed

The scales are normally set to display in kilograms, however they will show the weight in grams, if enabled.

The display will show “��” or “��”.

Press [Tare/�] to change the setting between �� or ��


The CBWa scales can change units from kilograms to grams, pounds or pounds/ounces immediately if they are enabled as in the step above. This also allows the scales to be calibrated in either kilograms or pounds and all memory accumulations are in either kilograms or pounds as last selected.

When the scales are set to display in other units of weight the accumulation function is still keeping the weight in kilograms (or pounds for the CBWa series) in memory and will use the base weighing unit when printing over the RS-232 interface.


Setting of the check weighing alarm

The display will show “��” where “�” is a digit from � to �.

� will set the buzzer to off when check weighing � will set the buzzer to on when the OK symbol is on � will set the buzzer to on when the weight is outside the OK symbol limit

To change this digit press the [Tare/�] key.

Press the [Zero/Enter] key to store the changed value and continue to the next parameter.

Speed at which the machine will run the ADC

The slowest setting is �� and the fastest is ��. The default setting is usually ��. The display will show “��”.

To change this setting press the [Tare/�] key.

Press [Zero/Enter] to store the changed value and return to the normal weighing.

6.0 TWO POINT FACTORY CALIBRATION This procedure is the same as normal calibration but can be set even if the stability indicator will not show or when the raw counts do not seem to be moving. Please ensure that the load cell is not damaged and that the load cell is wired correctly with the right output voltages. To start the factory calibration, turn the scale off and then turn it back on. Press the [Limit] and [%] keys together during the initial counting from 9 to 0 on the display. The display will show "��". Remove all weight from the pan and then press the [Zero/Enter] key to set the initial zero point when the scale is stable. The display will then show the first calibration weight used. This value will be one third of the scale capacity. Place this value weight on the scale and press the [Zero/Enter] key when the stable indicator is on The display will then show then second value weight to be used which will be full capacity of the scale. Place this value calibration weight on the platform and then press the [Zero/Enter] key when the stable indicator is on. Remove the calibration weight as the scale counts back from 9 to 0.


Calibration weights

CBW SERIES CBW 3 CBW 6 CBW 15 CBW 30 CBW 45

Weight 1 1000 g 2 kg 5 kg 10 kg 15 kg Weight 2 3000 g 6 kg 15 kg 30 kg 45 kg

CBWa SERIES CBW 6a CBW 12a CBW 35a CBW 65a CBW 100a

lb kg lb kg lb kg lb kg lb kg Weight 1 2 lb 1000 g 4 lb 2 kg 10 lb 5 kg 20 lb 10 kg 40 lb 15 kg Weight 2 6 lb 3000 g 12 lb 6 kg 30 lb 15 kg 60 lb 30kg 100 lb 45kg

6.1 ADC OUTPUT CHECKING

It is possible to check the raw count output of the Analogue to Digital Converter which will also verify if the load cell is in good condition. To start the ADC check, turn the scale off and then turn it back on. Press the [Zero/Enter] and [%] keys together during the initial counting from 9 to 0 on the display. The raw ADC counts will be displayed. With no load on the pan the raw counts should typically be between 10,000 and 100,000 although this is not critical. Different capacity scales have different load cells and the pan assembly will vary the dead load percentage of the cell. If with no load on the pan the counts are below 1000 or above 200,000 then the load cell should be tested as explained in the next section. Apply full capacity to the pan to verify that the raw counts increase to a value that will not exceed the capability of the ADC. Typically the raw counts will increase to a figure below 500,000 although if a mass has been added to the pan then this may be exceeded. If the counts go above 900,000 or decrease with load then please test the load cell for damage or incorrect wiring. To check if the ADC has a good output for best accuracy then empty the pan and press the [Zero/Enter] key to set the counts to “0”. Now apply full capacity to the pan and note the span of raw counts. Divide the number of counts by the number of displayed divisions (i.e. 30,000 as standard). If the input to the ADC is good then there should be approximately 10 or more counts per division for best accuracy. If there are less than 10 counts / d then check that the correct load cell is fitted and that the over load stops are adjusted correctly. To exit the ADC raw counts mode remove any weights and press the [Tare/�] key.


7.0 LOAD CELL DAMAGE

The most common reason a scale fails is that the load cell has been damaged. The damage can be from 2 primary causes. The first is physical damage due to an overload or an impact from the side and the second is damage due to the environment, such as moisture, extreme heat or a cut cable if the cables are exposed. PRINCIPLE OF OPERATION

The stain gauge load cell is a method of measuring the amount of stress put onto a metal structure due to a weight being supported by the structure. The stress is measured using 4 strain gage sensors mounted in a particular way on the metal structure. These 4 strain gauges are connected in such a way that they form a wheatstone bridge. See figure below. In the simplest load cells there are only the 4 resistances of the strain gages to consider. Normally without a load on the load cell all the resistances are the same. However when the load cell has a weight on it 2 of the strain gages will be in compression (A and D) and the resistance will decrease and 2 will be in tension (B and C) and their resistance will increase.

350 ohm

350 o

hm350 ohm

350 o

hm

A B

C D

+E

-S

-E

+S

BALANCED BRIDGE

10 VOLT POWERSUPPLY

Vout = O VOLTS,

BETWEEN +S AND -s

351 ohm

349 o

hm351 ohm

349 o

hm

A B

C D

+E

-S

-E

+S

UNBALANCED BRIDGEFULL CAPACITY LOADON THE LOAD CELL

10 VOLT POWERSUPPLY

Vout = 0.028 VOLTS (28mv),

BETWEEN +S AND -s


This will cause the bridge to become unbalanced. When the bridge has a voltage across it from +E to -E then the signal output at +S and -S will show a voltage of zero volts with no load and a small voltage proportional to the load as the load is increased. Typical load cells show 20-30mv of signal if the excitation voltage is 10volts and the load cell is fully loaded. Most load cells used in scales are not as simple as this example. They have additional resistance elements added to compensate for temperature variations and to set the outputs to correct voltages. The circuit of a typical load cell is shown below-

A method to check the basic function and integrity of a load cell can be done using a ohmmeter and voltmeter with up to a 10volt power supply. Before the load cell is connected to the power supply use the ohmmeter to measure the resistance between the wires. Typical resistance values are: +E to -E 410 ohms ±30 ohms +S to -S 350 ohms ± 2 ohms +E to +S or any other combination similar approximately 270 ohms. If the load cell has Sense connections in addition they are connected to the excitation internal to the load cell. Connect the load cell +E and -E to a power supply, typically 10 volts. Never use more than 12 volts as it may damage the load cell. Measure the voltage between +S and -S. With no load the voltage should be approximate 0mv ±3mv. With a mass on the load cell the output voltage should increase. The amount by which it increases will be dependent upon the sensitivity of the load cell, capacity of the load cell, the excitation voltage and the amount of mass placed on the load cell. Most load cells have a sensitivity of either 2mv/V or 3mv/V.


The expected change to the output is: Vout = (2mv/V) * Vext * Mass capacity of load cell For example a 2mv/V load cell of 30Kg capacity with 20Kg placed on it. Vext is 5 volts would give a output of approximately: Vout = (2mv/V) * Vext * Mass = 2mv/V * 5V * 20Kg = 6.7mv capacity of load cell 30kg If the load cell has been damaged the no load voltage will likely be greater than 3mv or the loaded voltage will be grossly different from the expected value. Remember the loaded voltage will be offset by the amount of zero load voltage measured. The load cell can be tested while it is connected to the A/D converter circuit board, using the scale power supply for excitation voltage. TESTING LOAD CELLS IN THE SCALE The signal from the load cells is amplified by the circuits on the A/D circuit board. The signal needs to be amplified to make it acceptable for the A/D converter used. The TCC/CBW scales amplify the input by 200, and change the no load voltage to about +2.5V. The TFC and TFW scales use a gain of 500. The amplified and offset voltage is measured at pin 6 of IC7, the INA118P amplifier IC. This voltage is sent to the filter and then to the A/D converter.

8.0 CBW RS-232 INSTALLATION The addition of the RS-232 interface for these scales requires the following: Scale Lead with 9-pin d-subminiature connector

Cover with RS-232 Connector Hole cut out A new main PCB with RS-232 interface included

The scale will have a PCB for the main parts of the electronics. These boards will not have any parts included for the RS-232 interface. Replace the main PCB with the new one which has the RS-232 interface included. Fit the CPU and the jumpers -taken from the earlier PCB into the new PCB. All parameters and Calibration including the Two Point Factory Calibration must be set before the new PCB will be put to use for weighing.


The 3 pin connector from the RS-232 connector goes to the main PCB. The 9 pin d-sub-miniature connector is attached inside the case using the 2 hex standoffs that come with the connector, with lock-washers and nuts. There is no special configuration or software that needs to be enabled for the interface to operate. The user manual has the details for the RS-232 interface in it. INSTALLING THE RS-232 IN CBW SCALES

• Remove the top pan and take out the 5 screws from the bottom of the scale.

2.

• Detach the 4 cables connected with the Load-cell, Display, Power Switch and Battery Chamber from the main PCB.

• Remove the main PCB by taking out the 4 screws from the 4 corners.

• Install a new main PCB

which has the RS-232 hardware already fitted into it.

• Plug in the RS-232

interface cable into the connector marked “SER”.

• Take-out the blanking label from the window provided on the right side of the scale.

• Fix the 9-pin D-subminiature connector in the cut-out of the window and secure it with the special screws provided.

• Remove the Microprocessor from the earlier PCB and install in the new


board and also if the link between K1 and K5, if any. Install the micro-processor and the links in the same way as it was in the old board into the new board. Be very careful not to bend the legs while removing the micro-processor.

• Plug the cables coming from the Load-cell, Display, Battery and Power

Switch into the main PCB.

• Turn the scale on to check whether the scale is working. Note that without the pan installed the scale may not show zero.

• Replace the cover back and secure it with all 5 screws.

• Place the stainless steel pan back on the scale.

• Switch the scale on to verify proper installation.

• Set the parameters as described in the Service Manual and perform the

Factory Calibration by using the [Limit] and [%] keys together.

• If the RS-232 needs to be disabled or configured, follow the procedure for parameter settings as given in the manual.

9.0 SCHEMATICS The following schematics are included as a guide for the experienced Service Technician. If you are not experienced we do not advice you to change parts on the circuit boards or otherwise disturb the electronics. If you require assistance please contact your dealer or Adam Equipment. We will be happy to help you resolve problems or determine the cause of a problem if you send us a full description of the scale and the problem. The following schematics are included.

CBW Main PCB assembly, pages 2


Manufacturer’s Declaration of Conformity

This product has been manufactured in accordance with the harmonised European standards, following the provisions of the below stated directives:

Electro Magnetic Compatibility Directive 89/336/EEC

Low Voltage Directive 73/23/EEC

Adam Equipment Co. Ltd.

Bond Avenue Denbigh East Estate

Milton Keynes, MK1 1SW United Kingdom

FCC COMPLIANCE

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. The equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense. Shielded interconnect cables must be employed with this equipment to insure compliance with the pertinent RF emission limits governing this device. Changes or modifications not expressly approved by Adam Equipment could void the user's authority to operate the equipment.


ADAM EQUIPMENT is an ISO 9001:2000 certified global organisation with more than 30 years experience in the production and sale of electronic weighing equipments. Products are sold through a world wide distributor network -supported from our company locations in the UK, USA and SOUTH AFRICA. The company and their distributors offer a full range of Technical Services such as on site and workshop repair, preventative maintenance and calibration facilities. ADAM’s products are predominantly designed for the Laboratory, Educational, Medical and Industrial Segments. The product range can be classified as follows:

− Analytical and Precision Laboratory Balances − Top Loading Balances for Educational establishments − Counting Scales for Industrial and Warehouse applications − Digital Weighing/Check-weighing Scales − High performance Platform Scales with extensive software features including parts counting, percent weighing etc. − Digital Electronic Scales for Medical use − Retail Scales for price computing

Adam Equipment Co. Ltd.

Bond Avenue Milton Keynes

MK1 1SW UK

Phone:+44 (0)1908 274545 Fax: +44 (0)1908 641339

e-mail:

[email protected]

Adam Equipment Inc. 26, Commerce Drive

Danbury, CT 06810 USA

Phone: +1 203 790 4774 Fax: +1 203 792 3406

e-mail:

[email protected]

Adam Equipment S.A. (Pty) Ltd. P.O. Box 1422

Kempton Park 1620 Johannesburg

Republic of South Africa

Phone +27 (0)11 974 9745 Fax: +27 (0)11 392 2587

e-mail:

[email protected]

© Copyright by Adam Equipment Co. Ltd. All rights reserved. No part of this

publication may be reprinted or translated in any form or by any means without the prior permission of Adam Equipment.

Adam Equipment reserves the right to make changes to the technology, features,

specifications and design of the equipment without notice.

All information contained within this publication was to the best of our knowledge timely, complete and accurate when issued. However, we are not responsible for

misimpressions which may result form the reading of this material.

The latest version of this publication can be found on our Website.

Visit us at www.adamequipment.com

CBW service revA3 - Adam Equipment USA...@Adam Equipment Company 2005 6 4.0 CBW DESCRIPTION The CBW...

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