OHAUS CKW-55 User manual

Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058 [phone]
CKW-55 INDICATOR
SERVICE MANUAL
T

The information contained in this manual is believed to be accurate at the time of publication,
but Ohaus Corporation assumes no liability arising from the use or misuse of this material.
Reproduction of this material is strictly prohibited.
Material in this manual is subject to change.
© Copyright 2006 Ohaus Corporation, all rights reserved.
® Registered trademark of Ohaus Corporation.
CKW-55 Indicator
CKW-55 Indicator
SERVICE MANUAL
T

i
TABLE OF CONTENTS
CHAPTER 1 INTRODUCTION
Page
1. Introduction ........................................................................................................ 1-1
1.1 Service Facilities .................................................................................................. 1-1
1.2 Tools and Equipment ........................................................................................... 1-2
1.2.1 Standard Tools and Test Equipment .......................................................... 1-2
1.2.2 Special Tools ......................................................................................... 1-2
1.3 Calibration Masses Required................................................................................. 1-2
1.4 Service Strategy ................................................................................................... 1-3
1.5 Safety and Environmental Protection ...................................................................... 1-3
CHAPTER 2 DIAGNOSIS
2. Diagnosis .......................................................................................................... 2-1
2.1 Basic Examination .............................................................................................. 2-1
2.2 Preliminary Checks .............................................................................................. 2-1
2.3 Troubleshooting Tables ........................................................................................ 2-1
2.4 Error Code Table .................................................................................................. 2-6
CHAPTER 3 CKW-55 INDICATOR TESTING
3. Indicator Testing.................................................................................................. 3-1
3.1 Membrane Switch Testing ..................................................................................... 3-1
3.2 Main PC Board Testing......................................................................................... 3-3
3.2.1 Voltage Measurements ............................................................................ 3-3
3.2.2 Simulator Testing .................................................................................... 3-6
3.3 Power Supply Testing ........................................................................................... 3-7
3.3.1 Voltage measurements ............................................................................ 3-7
3.4 Battery Testing .................................................................................................... 3-8
3.4.1 General Information ................................................................................ 3-8
3.4.2 Troubleshooting the Battery ...................................................................... 3-9
3.5 Recharge Board Testing ..................................................................................... 3-10
3.5.1 Recharge Board Information................................................................... 3-10
3.5.2 Recharge Board Testing......................................................................... 3-11
3.5.3 Voltage Measurements .......................................................................... 3-12
3.6 Relay Board Testing ........................................................................................... 3-13
3.6.1 Relay Kit Information ............................................................................. 3-13
3.6.2 Relay Testing........................................................................................ 3-13
3.7 RS322, RS422/485 Communication Testing ........................................................ 3-16
3.7.1 RS422/485 Communication Board Information ........................................ 3-16
3.7.2 RS232 Testing...................................................................................... 3-16
3.7.3 RS422/485 Testing............................................................................... 3-18
3.8 External Input Testing ......................................................................................... 3-20
3.9 Operational Testing ............................................................................................ 3-21
3.9.1 Indicator Display Segment Test- Power On Sequence ................................ 3-21
3.9.2 Turning Off the Indicator ......................................................................... 3-22
3.9.3 Performance Testing ............................................................................. 3-22
3.9.4 Checking Menu Library Settings .............................................................. 3-23

ii
TABLE OF CONTENTS (Cont.)
CHAPTER 3 CKW-55 INDICATOR TESTING (Cont.)
3.10 Specifications .................................................................................................... 3-25
3.11 Calibration using an External Base ...................................................................... 3-26
3.12 Calibration3-28
3.12.1 Span Calibration ................................................................................... 3-27
3.12.2 Linearity Calibration............................................................................... 3-28
3.14.3 Calibration Test ..................................................................................... 3-29
3.13 Geographical Adjustment Factor .......................................................................... 3-30
3.14 Calibration Verification using Load Cell Simulator ................................................... 3-32
3.14.1 Calibration Test Using a Simulator........................................................... 3-33
CHAPTER 4 REPAIR PROCEDURES
4. Repair Procedures................................................................................................ 4-1
4.1 Opening the Indicator Housing .............................................................................. 4-1
4.2 Replacing the Membrane Switch ............................................................................ 4-1
4.3 Replacing the Main PC Board ............................................................................... 4-2
4.4 Replacing the Power supply .................................................................................. 4-2
4.5 Replacing the Optional Recharge Board .................................................................. 4-3
4.6 Replacing the Optional Relay Board ....................................................................... 4-3
4.6.1 Relay Board Replacement Procedure ......................................................... 4-3
4.6.2 Relay Replacement ................................................................................. 4-4
4.7 Replacing the Optional RS422/485 Communication Board ...................................... 4-4
4.8 Replacing the Optional Rechargeable Battery .......................................................... 4-5
4.9 Replacing the Real-Time Clock (RTC) Battery .......................................................... 4-6
CHAPTER 5 PARTS LISTS
5. Parts Lists .......................................................................................................... 5-1
5.1 CKW-55 Indicator Exploded View .......................................................................... 5-2
5.2 CKW-55 Indicator Parts List.................................................................................. 5-3
5.3 CKW-55 Column Exploded View ........................................................................... 5-4
APPENDIX A SERVICE MODE ........................................................................................ A-1
A.1 Service Mode ...................................................................................................... A-1
A.1.1 Service Mode Commands ........................................................................ A-1

iii
TABLE NO. TITLE PAGE
1-1 Calibration Masses .............................................................................................. 1-2
2-1 Indicator Will Not Turn On With AC Power ............................................................... 2-1
2-2 Indicator Will Not Turn On Using Battery Power (Optional) ........................................ 2-2
2-3 Indicator Does Not Respond To Front Panel Controls ............................................... 2-3
2-4 No LED or Bar Display or Partial Display ................................................................ 2-3
2-5 RS232 Communication Failure.............................................................................. 2-4
2-6 RS422/485 Communication Failure (Optional Board) .............................................. 2-4
2-7 Relay Operation Failure (Optional board)................................................................ 2-4
2-8 Indicator Display Incorrect or Unstable ................................................................... 2-5
2-9 Unable to Maintain Time and Date Functions........................................................... 2-5
2-10 Error Code Table ................................................................................................. 2-6
3-1 Membrane Switch Continuity Test .......................................................................... 3-2
3-2 Serial Interface Commands Table ........................................................................ 3-17
3-3 External Input Selections ..................................................................................... 3-20
3-4 Specifications .................................................................................................... 3-25
3-5 Geographical Adjustment Values ......................................................................... 3-31
3-6 Load Cell Output Readings for CKW Bases ........................................................... 3-34
5-1 CKW-55 Indicator Parts List .................................................................................. 5-3
5-2 CKW-55 Column Parts List ................................................................................... 5-4
A-1 Service Mode Commands ..................................................................................... A-1
A-2 ASCII Number to Character Conversion ................................................................... A-2
LIST OF TABLES

iv
FIGURE NO. TITLE PAGE
3-1 Scale Membrane Switch Wiring Diagram ................................................................ 3-2
3-2 Interconnection Diagram ...................................................................................... 3-4
3-3 Component Layout Diagram ................................................................................. 3-5
3-4 Power Supply Location Diagram ........................................................................... 3-7
3-5 Battery Charging Indications ................................................................................. 3-8
3-6 Battery and Recharge Board location Diagram ........................................................ 3-9
3-7 Relay Board With Terminal Cover ........................................................................ 3-14
3-8 Relay Board Without Terminal Cover .................................................................... 3-14
3-9 RS422/485 Typical 4-wire Duplex Connection ...................................................... 3-18
3-10 RS422/485 Typical 2-Wire Half Duplex Connection ............................................... 3-18
3-11 RS422/485 Location in Housing ......................................................................... 3-19
3-12 Main Printed Circuit Board .................................................................................. 3-26
3-13 Open and Shorted Jumpers ................................................................................ 3-28
3-14 Main Printed Circuit Board Connections ................................................................ 3-32
3-15 Open and Shorted Jumpers ................................................................................ 3-32
4-1 RTC Battery Removal/Installation ........................................................................... 4-6
5-1 Exploded View of CKW-55 Indicator....................................................................... 5-2
5-2 Exploded View of CKW Column ............................................................................. 5-4
LIST OF ILLUSTRATIONS

1-1
CHAPTER 1 INTRODUCTION
1. INTRODUCTION
This service manual contains instructions for the diagnosis and repair work to be performed by qualified
Ohaus service technicians or Ohaus authorized service centers. Knowledge of the operation of the CKW-
55 Indicator is assumed. Instruction manuals may be required with this service manual. For complete
information on operation, refer to the CKW-55 Indicator and CKW Series Scale Instruction Manual.
This manual covers troubleshooting, repair and testing of the CKW-55 Indicator.
The contents of this manual are contained in five chapters and an Appendix with service menu instructions.
Chapter 1 Introduction - Contains information about service facilities, tools, test equipment, test
masses, and service strategy.
Chapter 2 Diagnosis - Contains information on problem verification, indicator examination, preliminary
checks, troubleshooting tables, interconnection diagrams and wiring diagrams.
Chapter 3 CKW-55 Indicator Testing and Calibration - Contains testing procedures, performance tests,
specifications and calibration of the CKW-55 Indicator.
Chapter 4 Repair Procedures - Contains detailed repair procedures for all major assemblies of the CKW-
55 Indicator including the optional Relay Board, RS422/485 Communication Board, the Recharge Board
and Battery.
Chapter 5 Parts Lists - Contains an exploded view identifying all serviceable replacement assemblies
with associated parts lists.
Appendix A CKW-55 Indicator Service Menu - Contains RS232 commands for the CKW-55 Indicator
in a service mode.
1.1 SERVICE FACILITIES
The service area should be a stable environment.
The bench area should be clean and should contain an antistatic mat with a personnel-grounding clip
to protect internal circuit boards. The ideal electrical power source for the indicator should be a dedicated
line to avoid sudden fluctuations or voltage drops caused by external equipment drawing heavy current.
The service area for the indicator should be away from direct sunlight, overhead heating or air conditioning
ducts, magnetic fields such as motors or large transformers or near vibrating sources such as machinery,
motors or vibrating equipment.
The power outlet should be grounded for safety. Sufficient space should be provided around the indicator
as not to be affected by other equipment. This will ensure that the indicator is operated under ideal
conditions.

1-2
CHAPTER 1 INTRODUCTION
1.2 TOOLS AND EQUIPMENT
1.2.1 Standard Tools and Test Equipment
The service shop should contain the following equipment:
1. Digital Voltmeter (DVM).
2. Megohmeter
3. Standard Electronics tool kit.
4. Desk magnifier on a stand.
5. Grounding mat and clip.
6. Flat blades and holder.
1.2.2 Special Tools
To service the CKW-55 Indicator, the following equipment is recommended:
1. A Load Cell Simulator
2. A computer
3. RS232 Cable Printer SF42 PN 80500574
4. RS232 Cable/PC 25-pin PN 80500553
5. RS232 Cable/PC 9-pin PN 80500552
1.3 CALIBRATION MASSES REQUIRED
The calibration masses required is dependent on the capacity and readability of the base used. The masses
required to test the CKW-55 Indicator when connected to an Ohaus CKW base must meet the requirements
of ASTM Class 4 or OIML F2. The mass values are listed in Table 1-1.
TABLE 1-1. CALIBRATION MASSES
MODEL Span Cal Linearity Cal
Cal in kg: Masses Totaling Masses Totaling
CKW3R55 3kg 1kg & 3kg
CKW6R55 6kg 3kg & 6kg
CKW15L55 15kg 7kg & 15kg
CKW30L55 30kg 15kg & 30kg
NOTE: During span calibration, a new span value may be entered. The span allowable range is 1kg or
1lb to 100% full scale. During linearity calibration a new midpoint value may be entered, the allowable
range is 25% to 75% full-scale capacity (whole numbers only). Values closest to 1/2 span capacity
will result in more accurate linearity.