Service Manual EN T21P 80252590.pdf

SERVICE MANUAL 2000 Series T21P Indicators

Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 (973) 377-9000

SERVICE MANUAL

2000 Series T21P Indicators

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 2008 Ohaus Corporation, all rights reserved. TM Registered trademark of Ohaus Corporation.

TABLE OF CONTENTS

Page No. CHAPTER 1 GETTING STARTED

1.1 Introduction ................................................................................................................1-1 1.2 Service Facilities........................................................................................................1-1 1.3 Tools and Test Equipment Required .........................................................................1-2

1.3.1 Special Tools and Test Equipment List ..............................................................1-2 1.3.2 Standard Tools and Test Equipment List ...........................................................1-2

1.4 Specifications.............................................................................................................1-2 1.6 Operation ...................................................................................................................1-4

1.6.1 Power Supply .....................................................................................................1-4 1.7 Overview of the Controls ...........................................................................................1-4

1.7.1 Power On ...........................................................................................................1-6 1.7.2 Power Off ...........................................................................................................1-6 1.7.3 Menu Setup ........................................................................................................1-6

1.8 Load Cell Connection ................................................................................................1-7 1.9 RS232 Interface Connection......................................................................................1-7

1.9.1 Hardware............................................................................................................1-7 1.10 Mounting the Column Bracket ...................................................................................1-8 1.11 Scale Setup and Calibration ......................................................................................1-9

CHAPTER 2 TROUBLESHOOTING

2.1 Introduction ................................................................................................................2-1 2.2 Visual Inspection........................................................................................................2-1 2.3 Diagnostic Guide .......................................................................................................2-2

2.2.1 Diagnosis............................................................................................................2-2 CHAPTER 3 MAINTENANCE PROCEDURES

3.1 Preventive Maintenance ............................................................................................3-1 3.1.1 Preventive Maintenance Checklist .....................................................................3-1

3.2 Replacement of Major Components ..........................................................................3-1 3.2.1 Main Printed Circuit Board (PCB) Replacement.................................................3-2 3.2.2 Keypad PCB Replacement.................................................................................3-3 3.2.3 Cable Set Replacement .....................................................................................3-4 3.2.4 Function Label Replacement..............................................................................3-5 3.2.5 Battery Replacement..........................................................................................3-6

CHAPTER 4 TESTING

4.1. Testing .......................................................................................................................4-1 4.2 Power Test.................................................................................................................4-1 4.3 Performance Tests Using a Scale Base ....................................................................4-1

4.3.1 Increasing/Decreasing Load Test.......................................................................4-2 4.3.2 Overload/Underload Test ...................................................................................4-2

4.4 Performance Tests Using a Load Cell Simulator.......................................................4-3 4.5 Calibration Retention .................................................................................................4-3 4.6 RS232 Interface Test................................................................................................. 4.3 4.7 Print Test ...................................................................................................................4-3

CHAPTER 5 PARTS LISTS & DIAGRAMS

5-1 2000 Series T21P Indicator: Housing & Internal Parts ..............................................5-2

Ohaus Corporation www.ohaus.com 1 2000 Series T21P Indicator Service Manual

LIST OF TABLES

TABLE NO. TITLE Page No. 1-1 Specifications ........................................................................................................1-3 1-2 Functions of Display Controls................................................................................1-5 1-3 Load Cell Connector Pin Connections ..................................................................1-7 2-1 Diagnostic Guide...................................................................................................2-3 4-1 RS232 Menu Structure..........................................................................................4-3 4-2 Linearity Test Masses ...........................................................................................4-3 5-1 T21P Indicator: Housing & Internal Parts ..............................................................5-3

LIST OF ILLUSTRATIONS

FIGURE NO. TITLE 1-1 T21P Display.........................................................................................................1-4 1-2 T21P Indicator, side view and rear view................................................................1-6 1-3 View of pins on the Load Cell Cable Connector....................................................1-7 1-4 View of RS232 Pins on indicator ...........................................................................1-7 1-5 Mounting Column Bracket to T21P .......................................................................1-8 2-1 Visual Checking Procedures .................................................................................2-1 5-1 Series 2000 T21P Indicator: Housing & Internal Parts..........................................5-2

2000 Series T21P Indicator Service Manual 2 Ohaus Corporation www.ohaus.com

CHAPTER 1 GETTING STARTED

1.1 INTRODUCTION

This service manual contains the information needed to perform routine maintenance and service on the Ohaus T21P Indicators. The contents of this manual are contained in five chapters:

Chapter 1 Getting Started Contains information regarding service facilities, tools and test equipment, measuring masses, specifications, and the mechanical and electronic functions of the indicator.

Chapter 2 Troubleshooting Contains a diagnosis/diagnostics chart and error code table.

Chapter 3 Maintenance Procedures Contains preventive maintenance procedures and disassembly, repair and replacement procedures.

Chapter 4 Testing Contains an operational test, segment display test, performance tests and adjustments.

Chapter 5 Drawings and Parts Lists Contains exploded views of T21P Indicators, identifying all serviceable components.

Before servicing the indicator, you should be familiar with the Instruction Manual which is packed with every indicator.

1.2 SERVICE FACILITIES

To service an indicator, the service area should meet the following requirements:

Must be protected from electrostatic discharge. Should be temperature controlled and meet the indicator specifications for temperature

environmental requirements. See specifications for temperature range.

Must be free of vibrations such as fork lift trucks close by, large motors, etc. Must be free of air currents or drafts from air conditioning/heating ducts, openwindows,

people walking by, fans, etc.

Area must be clean and air must not contain excessive dust particles. Work surface must be stable and level. Work surface must not be exposed to direct sunlight or radiating heat sources.

2000 Series T21P Indicator Service Manual 1-1 Ohaus Corporation www.ohaus.com


1.3 TOOLS AND TEST EQUIPMENT REQUIRED

In order to properly service the Indicator, certain special tools and test items are required in addition to standard electronic tool kits. These items are listed as follows:

1.3.1 Special Tools and Test Equipment List

1. Ohaus Scale Base.

2. Load Cell Simulator optional.

3. Computer with RS232 Interface.

4. RS232 Interface cable.

5. Data Printer for use with RS232 communications.

6. ESD work station or mat.

1.3.2 Standard Tools and Test Equipment List

1. Standard Electronics Tool Kit

2. Digital Voltmeter (DVM), with clip on probes. Input impedance of at least 10 megohms in the 1 Volt dc position.

3. Soldering Iron, solder and flux remover.

Ohaus Corporation www.ohaus.com 1-2 2000 Series T21P Indicator Service Manual


1.5 SPECIFICATIONS

TABLE 1-1. SPECIFICATIONS

Model T21P

Housing Dimensions 250W x 142D x 180H mm (without column bracket)

Full Scale Capacity Range 5 to 20,000 kg or lb

Recommended Displayed Resolution 1:10,000d

Minimum Average Piece Weight (APW) 0.25d

Weighing Units Kilograms, Pounds

Functions Parts Counting, Weighing, Weight Accumulation, Check Weighing

Sample Size User configurable up to 99,999

Display LED, (20 mm / 0.8 in high ), 6-digit 7-segment

Keypad 6 function mechanical switches, raised, tactile

Load Cell Drive Up to 4 x 350 ohm load cells

Load Cell Excitation Voltage 5V DC

Load Cell Input Sensitivity Up to 3mV/V

Stabilization Time 2 secondsAuto-Zero Tracking Off, 0.5, 1, 2, 3, 4 or 5 divisions

Key Zeroing Range 2%, 5%, 10%, 20% of capacity

Span Calibration 1kg or 1lb to 100% of capacity

Interface Simplex RS232C

Power requirements 9 VDC 500 mA AC adapter (supplied)

Battery 6V 4Ah Internal rechargeable sealed lead acid battery 30-hour typical operation with 12-hour full charge

Operating Temperature Range -10C to 40C

Net Weight 2 kg / 4.4 lb

Shipping Weight 2.5 kg / 5.5 lb

Shipping Dimensions 320w x 210d x 236h



1.6 OPERATION

This section contains information on the basic operation of the. An exploded view drawing is included in Chapter 5 which identifies all components of the indicator. The descriptions in this manual refer to the names of the components identified in the exploded view drawing with the numbered callout.

1.6.1 Power Supply

Power to the indicator is supplied by a 9 V dc, 500mA Power Adapter, or by a 6V 4Ah Internal rechargeable sealed lead acid battery. The indicator will automatically switch to battery operation if there is a power failure or the power cord is removed.

NOTE Before using the Indicator for the first time, the battery should be fully charged for up to 12 hours. The Indicator can be operated during the charging process. The battery is protected against over-charging and the Indicator can remain connected to the AC power line.

The indicator can operate up to 30 hours on a fully charged battery. It automatically enters standby mode after one minute of no activity. The display will show only the decimal point [ . ]. Press on the pan or any key to resume. During battery operation, the Low Bat LED will illuminate when the battery is low and requires recharging. Approximately 30 minutes of operation will remain. The indicator automatically turns off when the battery is fully discharged.

1.7 OVERVIEW OF THE CONTROLS

AC LED

Low Bat LED

7-segment, 6-digit LED display

Zero, Tare, Stable, Accum, Pcs, Unit LEDs

Over, Under, Accept LEDs

Control Buttons

Figure 1-1. T21P Display.




TABLE 1-2. FUNCTIONS OF DISPLAY CONTROLS

Button

Primary Function (Short Press) n/a

Sample Enters Sample Setup

Saves APW*

Zero Sets zero

Secondary Function (Long Press)

SET Enters Menu Mode Enters Calibration

Menu during startup

APW* Displays APW* value N/A

Menu Function (Short Press)

Saves Settings and exits the menu N/A

ENTER Accepts the current

setting on the display

Button

Primary Function (Short Press)

TARE Tares weight of item

on pan

M+ Stores displayed weight in

accumulation memory Displays accumulation data

when display is zero

PRINT Sends the current

value to the RS232 Interface

Secondary Function (Long Press) N/A N/A

MODE Change between

weighing and counting mode

Menu Function (Short Press)

Decrement value of settings

Increment value of settings

Shift to next digit when setting parameters

*APW means Average Piece Weight.




On/Off Power Switch

RS232 Connector

Load Cell Connector Power

Receptacle

Figure 1-2. T21P Indicator, side view and rear view.

1.7.1 Power ON

To turn the indicator on, toggle the switch on the right side to the on position. (See Figure 1-3.) The indicator performs a display test, momentarily displays software version, and then enters the active weighing mode.

1.7.2 Power OFF

To turn the power off, toggle the switch to the off position.

1.7.3 Menu Setup

To enter the Menu Mode, press and hold the SET button for three seconds.

[SET-Fx] will be displayed where x =:

0 = Set upper and lower limit value.

1 = User Settings Menu.

2 = Restores settings to factory default.

3 = Set tare capacity between 2/3Max. and full scale.

To navigate in the Menu Mode:

Press to toggle through available settings. Press ENTER to accept the displayed setting and advance to the next step.

Press SET at any time to save settings and return to weighing.

For a complete guide to menus and modes, see the Instruction Manual.



1.8 LOAD CELL CONNECTION

Solder the load cell cable to the supplied load cell cable connector.

5 4 3 2 1

9 8 7 6

Figure 1-3. View of pins on the Load Cell Cable Connector.

TABLE 1-3. LOAD CELL CONNECTOR PIN CONNECTIONS Pin 1 2 3 4 5 6 7 8 9

Connection SIG SENS N/C N/C GND SENS+ EXC+ EXC SIG+ NOTE: To use a 4 wire load cell cable you must short pin 2 to 8, and pin 6 to 7.

CAUTION: Never connect a communication cable to the load cell connector of the Indicator. Switch the indicator off when you insert or remove the load cell cable connector from the Indicator.

NOTE: The load cell cable connector cannot pass through the supplied column bracket. Connect the load cell cable connector to the load cell cable after routing the cable through the column and column bracket. (See Section 1.10.)



1.9 RS232 INTERFACE CONNECTION

The T21P Indicator is equipped with a standard IBM compatible, one-way RS232 interface for communication with printers and computers. When the Indicator is connected directly to a printer or Programmable Logic Controller (PLC), displayed data can be recorded at any time by simply pressing the PRINT button, or it can be set for continuous printing.

Note: The T21P does not support two-way communication it can only send, not receive data.

1.9.1 Hardware

A 9-pin D female connector is located at the left side of the Indicator. Pin connections are shown in Figure 1-5. Connect an Ohaus RS232 cable to the Indicator.

RS232 Interface Pin Connections Pin 1: N/C Pin 2: RXD Pin 3: TXD Pin 4: N/C Pin 5: GND Pin 6-9: N/C

5 4 3 2 1

9 8 7 6

Figure 1-4. View of RS232 Pins on indicator.

1.9.2 Setting Communications Parameters

The T21P Indicators default communication parameters are 9600 baud, 8 databits, and no parity. Only the baud rate can be changed, as follows:

1. Enter the Menu Mode: press and hold the SET button for 3 seconds. [SET-Fx] appears.

2. Press to display [SET-F1] the User Settings Menu. 3. Press ENTER (Zero/Enter) to accept the displayed setting.

4. Accept the default settings for F1-0 through F1-5. (Press ENTER for F1-0 0, F1-1 1, F1-2 2, F1-3 0, F1-4 1, and F1-51.)

5. At F1-6, choose the desired baud rate: 0=9600 (default), 1=4800, 2=2400, 3=1200, and press ENTER.)

6. At F1-7, choose the preferred RS232C Output Mode: 0=output Gross, Net, Tare on PRINT key press only (default) 1=output G.N.T., transmit continuously 2=output G.N.T., transmit continuously after stable

7. After selecting the preferred F1-7 option and pressing ENTER, press SET to save the settings and return to weighing mode.



1.10 MOUNTING THE COLUMN BRACKET

The Indicator can be mounted to a scale column of 38mm outside diameter with the supplied column bracket.

1. Route the cable through the column and the column bracket.

2. Slide the column bracket down onto the column and tighten the nut.

3. Solder the load cell cable to the supplied load cell cable connector. (See Section 1.8.)

4. Slide the indicator onto the bracket as shown below.

5. Plug the load cell cable into the Indicators load cell connector. (See Figure 1-3.)

6. Remove the upper knob to change the viewing angle, re-install the knob to fix the position.

Figure 1-5. Mounting Column Bracket to T21P.



1.11 SCALE SETUP AND CALIBRATION

NOTES:

1. Make sure that appropriate calibration kilogram masses are available before beginning calibration.

2. Make sure that the scale base is level and stable during the entire calibration process.

3. Allow the Indicator to warm up for approximately five minutes after stabilizing to room temperature.

4. To abort calibration, press and hold the SET button for three seconds any time during the calibration process. Or turn the unit off.

Turn on the Indicator. During startup display sequence press and hold SET until [FS__SP] is displayed. Then follow these steps:

1. Press ENTER to display [P___x] (x=position of decimal point: 0, 1, 2, 3, and 4).

2. Press , to select the desired setting.

3. Press ENTER to display [D___x] (x=divisions: 1, 2,5,10, 20, and 50).

4. Press , to select the division. 5. Press ENTER to display Maximum Capacity Setting.

6. Press ,, to set the desired value. The LED row below the display refers to the active segment.

7. Press ENTER to accept and [noLoad] is displayed. Make sure the weighing platform is empty.

8. Press ENTER to accept and [Load] is displayed.

9. Press ENTER to display [xxxxxx] (xxxxx = Span Weight).

10. Press ,, to set a different value. 11. Place calibration weight on the weighing platform.

12. Press ENTER to accept and store data.

[CALEnd] will be displayed for two seconds and the Indicator will enter weighing mode.



2.1 INTRODUCTION

This section of the manual covers visual inspection of the Indicator, troubleshooting, and a Diagnostic Guide, Table 2-1. For setup and connection to either a known good base or simulator, see Chapter 1. Follow all directions step by step. Make certain that the work area is clean and use care when handling components of the Indicator.

2.2 VISUAL INSPECTION

Carefully remove the Indicator from its packing container and remove any packing material fastened to the unit. Note all items supplied with the unit such as AC power supply, cables, instruction manual, weights, etc. Keep a record of all items and note their condition.

1. Examine the Indicator for signs of abuse such as a cracked top cover or base, damage from liquids, cracks on corners, which may suggest the unit was dropped.

2. Open the Indicator by removing the four screws in the rear housing. Be careful not to stretch the cables that connect the main Printed Circuit Board (PCB) to the outlets (RS232 and Load Cell ports) and power supply.

3. Examine the top of the main PCB for cracks or signs of corrosion.

4. If it appears that corrosion may have affected the board and you want to examine the bottom of the PCB, remove the four screws holding it to the housing.

5. Carefully lift out the main PC board. If it is cracked or shows signs of corrosion, it requires replacement. See Chapter 3, Maintenance Procedures, for board replacement and testing. If the Indicator shows no sign of physical damage, continue with procedures.

See chart below for visual checking procedures.

VISUAL CHECKSEXTERNAL &

INTERNAL

CRACKEDTOP COVER

CRACKEDBOTTOM COVER

CRACKEDMAIN PC BOARD

RS232 CONNECTOR PINS BROKEN

LCD DISPLAY PARTIALLY LIT OR

BLACKENED

PANEL SWITCHES NON-FUNCTIONAL

REPLACE TOP COVER

REPLACE BOTTOM COVER

REPLACE MAIN PC BOARD

REPLACE RS232 CONNECTOR

REPLACE MAIN PC BOARD

SUBSTITUTE TOP COVER

VERIFY IF TOP PANEL OR MAIN PC

BOARD IS BAD

REPLACE TOP PANEL OR

MAIN PC BOARD

ASSEMBLE AND TEST

Figure 2-1. Visual Checking Procedures.

2000 Series T21P Indicators Service Manual 2-1 Ohaus Corporation www.ohaus.com


2.3 DIAGNOSTIC GUIDE

Table 2-1 is a Diagnostic Guide designed to help locate the problem area quickly and easily. The probable causes are listed with the most common cause first. If the first remedy does not fix the problem, proceed to the next remedy. Before attempting any repairs, read all chapters of this manual to be familiar with overall operation and all components.

2.2.1 Diagnosis

1. Isolate and identify the symptom

2. Refer to Table 2-1, Diagnostic Guide and locate the symptom.

3. Follow the suggested remedies in the order they appear.

4. Perform the indicated checks, or see the appropriate section of the manual.

5. Repair or replace the defective part.

NOTE: If more than one symptom is observed, approach one area at a time, and remember that the symptoms may be interrelated.

If a problem arises that is not covered in this manual, contact Ohaus Corporation for further information.

Ohaus Corporation www.ohaus.com 2-2 2000 Series T21P Indicators Service Manual


2.2.1 Diagnosis

TABLE 2-1. DIAGNOSTIC GUIDE

Symptom Possible Cause(s) Remedy Scale will not turn on No power to scale

Battery power used up Verify connections and voltage. Connect power and charge battery.

Poor accuracy Improper calibration Unstable environment

Perform calibration. Move scale to suitable location.

Unable to calibrate Unstable environment Incorrect calibration mass

Move the scale to suitable location. Use correct calibration mass.

Battery fails to charge fully

Battery is defective. Replace battery.

Display = Zero-E Pan has excessive load during power on. No span calibration

Remove weight from pan and re-zero. Perform Span Calibration.

Display = 000000 or 999999; or no weight reading

Load cell connector is disconnected. No calibration data in EEPROM

Connect the load cell connector. Calibrate the Indicator.

No display or AC LED is off

Power cable is defective. Battery is defective.

Check power cable. Replace battery.

Low Bat LED is lit Battery is weak. Connect power cable to AC. Charge the battery.

Display = Cou-no No sample quantity to be set Set sample quantity.

Display = L0_rEF APW is less than 0.25d. Use APW > 0.25d.

0ver Accumulation records are greater than 999, or total weight accumulation is greater than displayable range.

Clear Accumulation data.

Ad__Lo Calibration weight exceeds maximum displayed resolution.

Change range and resolution.


CHAPTER 3 MAINTENANCE PROCEDURES

3.1 PREVENTIVE MAINTENANCE

Ohaus Indicators are precision instruments and should be carefully handled, stored in a clean, dry, dust-free area, and cleaned periodically. Follow these precautionary steps:

When an Indicator has had chemicals or liquids spilled on it, all exterior surfaces should be cleaned as soon as possible with warm water on a damp cloth.

Allow at least 10 minutes for the scale to stabilize after moving it from an area which is at a different temperature than the area where it is to be operated.

3.1.1 Preventive Maintenance Checklist

The Indicator should be inspected and checked regularly, as follows:

1. Unplug the AC Adapter before cleaning.

2. Clean the outside of the scale using a damp cloth with warm water.

CAUTION DO NOT USE CHEMICAL CLEANERS OR SOLVENTS OF ANY TYPE. SOME CLEANERS ARE ABRASIVE AND MAY AFFECT THE SCALES FINISH.

3. Check the Power Cord for broken or damaged insulation.

4. Make a visual inspection for faulty connectors, wiring, and loose hardware.

3.2 REPLACEMENT OF MAJOR COMPONENTS

The decision to replace any component should only be made after thoroughly diagnosing the problem. If, after the replacement of any component, the Indicator is still non functional and no other information on the subject is available in the manual, contact Ohaus Corporation by visiting www.ohaus.com. In the United States call Ohaus Aftermarket toll free, 800-526-0659 between 8:00 a.m. and 4:00 p.m. EST.



3.2.1 Main Printed Circuit Board (PCB) Replacement

Repairs are not recommended on the Main PCB. Component parts of the PCB are not stocked by Ohaus. Replacement is recommended rather than repairing.

Replace the Main PCB for any of the following reasons:

Display is defective; characters missing or partial display.

Indicator fails to calibrate properly.

Display is erratic or unstable.

Certain functions are not operational.

Indicator does not operate at all.

1. Unplug the Indicator from the AC Adapter.

2. Disconnect the base scales Load Cell Cable from the Load Cell Connector on the Bottom Housing.

3. Remove the four screws from the Bottom Housing.

4. Carefully separate the Top Housing and Bottom Housing.

5. Remove the four screws from the Main PCB.

CAUTION When handling the PCB, grasp it by the edges only! Do not touch the foil side. Static discharge may damage some components.

6. Carefully remove the four sets of cables connected to the Main PCB. Three of the four sets have connector plugs with small locking tabs which must be pried out slightly to release the plug from the board. The fourth set, to the Load Cell connector, must be un-soldered from the PCB.

7. Lift out the Main PCB.

8. Carefully re-position the replacement Main PCB over the screw holes in the Top Cover, and re-insert and tighten the screws.

9. Reconnect the cable sets removed in Step 5.

10. Reconnect the base scales Load Cell Cable to the Load Cell Connector on the Bottom Housing.

11. Perform calibration procedures. (See Section 1.11.)

12. Perform testing procedures. (See Chapter 4.)



3.2.2 Keypad PCB Replacement

Repairs are not recommended on the Keypad PCB. Component parts of the PCB are not stocked by Ohaus. Replacement is recommended rather than repairing.

Replace the Keypad PCB if any of the Control Keys fails to function properly.





5. Remove the 8-cable plug securing the Keypad PCB Cable Set to the Main PCB.

6. Remove the five screws from the Keypad PCB.

CAUTION When handling the PCB, grasp it by the edges only! Do not touch the foil side. Static discharge may damage some components.

7. Lift out the Keypad PCB.

8. Carefully re-position the replacement Keypad PCB over the screw holes in the Top Cover. Note that the RS232 Cable Set runs under the lower-left side of the PCB, just inside the lower-left screw position. Re-insert and tighten the screws.

9. Reconnect the PCB Cable Set to the Main PCB.

10. Reconnect the base scales Load Cell Cable to the Load Cell Connector on the Bottom Housing.





3.2.3 Cable Set Replacement

Note: The cables that connect the Main PCB to the Keypad PCB, the Load Cell connector, the RS232 connector, the AC power outlet, the On/Off Switch, and the Lead Acid Battery, are all sold as a single set. Replace them singly or together, as follows:

1. Remove the Main PC board: Steps 1 7 of Section 3.2.1.

CAUTION When handling the PC board, grasp it by the edges only! Do not touch the foil side. Static discharge may damage some components.

2. The individual cable sets are located as follows:

The Keypad PCB Cable Set connects to the Main PCB through an 8-wire plug inserted just below the T21P chip on the Main PCB.

The Load Cell Cable Set connects at the top-right of the Main PCB through seven wires that are soldered directly to the Main PCB. These wires must be unsoldered to release the Cable Set.

The RS232 Cable Set connects to the Main PCB through a 3-wire plug inserted on the lower-left of the Main PCB.

The AC and Battery Cable Set connects to the Main PCB through a 6-wire plug inserted on the top-left side of the Main PCB.

3. If necessary, clip the plastic clamps that secure the cable set(s) to the Keypad PCB.

4. Remove screws or nuts from any of the connectors for which the cable set(s) will be replaced, to facilitate unsoldering and resoldering cables. In the case of the On/Off Switch, squeeze the plastic tabs that secure the switch housing in order to release it.

5. Unsolder the cables from any of the connectors (RS232, Load Cell, On/Off Switch, AC outlet) for which the cable set is to be replaced. In the case of the battery, remove the quick-connect tabs that hold the cables in place.

6. In replacing the cables, note in the case of the battery that the new cable set does NOT come with quick-connect tabs insert the replacement wire using new quick-connect tabs acquired separately. For the other connectors, carefully solder the replacement wires in place.

7. Reconnect the wires to the Main PCB, using the original plastic tabs, if available.



3.2.4 Function Label Replacement

When the Function Label is replaced, the Display Window should be replaced with it. Both items are supplied together.


2. Lift the Function Label off from the Top Cover. Remove the old Display Window. The Function Label is held in place with a strong adhesive. Clean the Top Cover and remove all traces of adhesive.

CAUTION Be careful placing the Function Label into position as the adhesive will not allow repositioning once attached to the cover.

3. Put the new Display Window in place.

4. Remove the protective backing from the back of the new Function Label, and carefully position it on the Top Cover, starting at the bottom of the cover. Use a rolling motion to smooth the Function Label into position.





3.2.5 Battery Replacement





5. Remove the four screws, each with a metal washer and a black plastic washer, that secure the Battery to the Bottom Housing.

6. Carefully lift away the bracket that holds the Battery in place.

7. Remove the quick-connect tabs that hold the Battery Cables in place, using needle-hose pliers.

8. Position the replacement Battery in the place of the old one. Insert the quick-connect tabs as they were before.

9. Reposition the bracket that holds the Battery in place, and insert the four screws, each with a metal washer and a black plastic washer, that secure the Battery to the Bottom Housing. (Note: The screws enter the Bottom Housing at a slight downward angle. It is easier to insert all four and assure that each connects with the threading before tightening any of them.)

10. Reassemble the Top Housing and Bottom Housing, and reconnect the Load Cell Cable to the Load Cell Connector on the Bottom Housing.




CHAPTER 4 TESTING

4.1 TESTING

Before and after servicing the Indicator, operational and performance tests should be made to determine if it meets specifications. Turn the Indicator ON and allow it to warm up for at least 10 minutes before performing these checks. The masses used for calibration should be ASTM Class 4 or OIML Class F2 tolerance or better.

NOTE: Make sure the test area is free from drafts and that the base rests on a level and vibration-free surface. The masses used for final calibration must be adjusted to ASTM Class 4 or OIML Class F2 tolerance or better.

4.2 Power Test

The purpose of this test is to determine if the electronic circuitry of the Indicator is functioning properly or not at all. In some cases, the AC Adapter supplied with the Indicator may have become defective.

1. Connect a functioning AC Adapter to the Indicator power plug.

2. Plug the AC Adapter into a suitable power source.

3. With the Indicator connected to an appropriate power supply, press the ON/OFF button. The Indicator performs a self-test, indicates the software revision and then goes into weighing mode.

4. If all of the displays appear normal in this test, continue with the next test. If the display did not appear, check the ac adapter output and repeat the test with a good adapter. If the display was erratic, the PC board is defective and requires replacement.

4.3 Performance Tests Using a Scale Base

These tests are performed on the Indicator using a known good scale base and test mass. At this point, the Indicator has been checked for full display, menu setup and calibrated.

If a Load Cell Simulator is being used, proceed to paragraph 4.4.

Select the maximum possible resolution (

CHAPTER 4 TESTING

4.3.1 Overload/Underload Test

This test determines if the Indicator displays the proper indication when an underload or overload condition exists on the scale base.

1. With the Indicator ON and no mass on the scale base, lift up on the scale base platform and observe the display. The display should indicate Error 2. Release the platform. The display should return to zero.

2. Place a mass on the scale base platform which exceeds the capacity of the scale base, and observe the Indicator display. The display should indicate Error 1. Remove the mass from the scale base. The display should return to zero.

4.4 Performance Tests Using a Load Cell Simulator

A simulator can be used in place of a scale base if available.

Connect the simulator to the 9-pin Load Cell connector on the back of the Bottom Housing. (See Figure 1-2, page 1-4.)

Test the Indicator as follows:

1. Set the simulator to zero. Power on the Indicator. Perform a Span Calibration, with zero at the simulators zero setting, and 100% capacity at the simulators 2.0 milli-volt setting.

2. Following calibration, check that the Indicators display reading is stable at each simulator level, up to the maximum set in the calibration. If the readings are stable, the Indicator is functioning properly.

4.5 Calibration Retention Test

This test checks that the Indicator retains calibration after power is removed and then restored.

1. Turn the Indicator OFF and disconnect the AC Adapter.

2. Wait one minute, then reconnect the AC Adapter to the Indicator.

3. Check to insure that the Indicator retained calibration settings.

4.6 RS232 Interface Test

The RS232 Interface performance can be monitored using an external printer or computer connected to the Indicator. The RS232 Interface is a one-way interface which enables the Indicator to communicate with a printer or computer equipped with an RS232 serial port.

To set up communication parameters, see Section 1.9.2.

4.7 Print Test

Once the communications parameters match between the Indicator and either a computer or printer, it is possible to test the Indicators print function.

Press the Print/Mode button. Printing to an external printer or computer should occur each time the button is pressed.

Note: Communication is only one-way from the T21P, not two-way. The T21P cannot receive data from an external computer.



This section of the manual contains exploded views for the 2000 Series T21P Indicator. The exploded view drawings are designed to identify the parts which can be serviced on the balance in the field.

NOTE: In all cases where a part is replaced, the balance must be thoroughly checked after the replacement is made. The balance MUST meet the parameters of all applicable specifications in this manual.

If further technical information is needed, please contact your local Ohaus distributor, or: Ohaus Corporation, www.ohaus.com 19A Chapin Road P.O. Box 2033 Pine Brook, NJ 07058-2033 USA Tel: 973-377-9000 Fax: 973-593-0359 In the United States call toll free, 800-526-0659 between 8:00 a.m. and 6:00 p.m. EST.



5.1 2000 SERIES T21P INDICATOR: HOUSING & INTERNAL PARTS

Figure 5-1. Series 2000 T21P Indicator: Housing & Internal Parts.



5.1 2000 SERIES T21P INDICATOR: HOUSING & INTERNAL PARTS

TABLE 5-1. T21P INDICATOR: HOUSING & INTERNAL PARTS

Drawing Item Description

1 Function Label with Display Window

2 Top Housing

3 Cable Sets

4 Main Printed Circuit Board (PCB)

5 Keypad PCB

6 Load Cell Cable Connector

7 Lead Acid Battery

8 Bottom Housing

9 On/Off Switch

10 Jack for Power Adapter

11 Column Mount Kit

70 Screws & Washers

80 Adapter


*80252590* P/N 80252590 SERVICE MANUAL: 2000 SERIES T21P INDICATOR

Table of ContentsChapter 11.1 INTRODUCTION1.2 SERVICE FACILITIES1.3 TOOLS AND TEST EQUIPMENT REQUIRED1.3.1 Special Tools and Test Equipment List1.3.2 Standard Tools and Test Equipment List

1.5 SPECIFICATIONS 1.6 OPERATION1.6.1 Power Supply

1.7 OVERVIEW OF THE CONTROLS 1.7 OVERVIEW OF THE CONTROLS1.7.1 Power ON1.7.2 Power OFF1.7.3 Menu Setup

1.8 LOAD CELL CONNECTION1.9 RS232 INTERFACE CONNECTION1.9.1 Hardware1.9.2 Setting Communications Parameters

1.10 MOUNTING THE COLUMN BRACKET 1.11 SCALE SETUP AND CALIBRATION

Chapter 22.1 INTRODUCTION2.2 VISUAL INSPECTION 2.3 DIAGNOSTIC GUIDE2.2.1 Diagnosis 2.2.1 Diagnosis

Chapter 33.1 PREVENTIVE MAINTENANCE3.1.1 Preventive Maintenance Checklist

3.2 REPLACEMENT OF MAJOR COMPONENTS 3.2.1 Main Printed Circuit Board (PCB) Replacement 3.2.2 Keypad PCB Replacement3.2.3 Cable Set Replacement 3.2.4 Function Label Replacement 3.2.5 Battery Replacement

Chapter 44.1 TESTING4.2 Power Test4.3 Performance Tests Using a Scale Base 4.3.1 Overload/Underload Test

4.4 Performance Tests Using a Load Cell Simulator4.5 Calibration Retention Test4.6 RS232 Interface Test4.7 Print Test

Chapter 5 5.1 2000 SERIES T21P INDICATOR: HOUSING & INTERNAL PARTS5.1 PARTS EXPLODED VIEW 5.1 PARTS LIST

Service Manual EN T21P 80252590.pdf

Documents

Transcript of Service Manual EN T21P 80252590.pdf