DL37_SM_e_710142

BildBild

Edition: June 1998

METTLER TOLEDOAnalytical

Service Manual

METTLER TOLEDOKF-Coulometer DL37

© Mettler-Toledo GmbH 1992, 1998 ME-704726A Printed in Switzerland 9806/8.12

Business location Schwerzenbach:Address Sonnenbergstrasse 74 (Industrie Vieri), 8603 Schwerzenbach, Switzerland

Phone 01-806 77 11Fax 01-806 73 50

Current status of the service manual, see section E

*P704726*

General

Cautionary noteExploded view diagramsSpare parts listService toolsInstrument layout

Checklist maintenanceChecklist serviceService modeFunction test

FusesTest pointsTroubleshooting

Corrective maintenanceCalibration and checking the boards

Supplements

Checking

Troubleshooting

Repairs

Service bulletins

Data section Circuit and board component diagrams

DL37 General

Service Manual ME-704726A 6/98 A-1

Contents Page

1. Cautionary notes ...................................................................................................... 3

2. General information .................................................................................................. 4

2.1 Technical changes ..................................................................................................... 42.1.1 Software changes ...................................................................................................... 42.1.2 Software changes overview ......................................................................................... 42.1.3 Hardware changes ..................................................................................................... 52.1.4 Software compatibility ................................................................................................ 5

3. Exploded view diagrams ........................................................................................... 6

3.1 Mechanical layout ...................................................................................................... 6

3.2 Printer mechanism ..................................................................................................... 7

3.3 Electrical layout ......................................................................................................... 8

3.3 Cable connections ..................................................................................................... 9

4. Spare parts list ......................................................................................................... 10

5. Service tools ............................................................................................................ 12

6. Instrument layout ...................................................................................................... 13

6.1 Mechanical layout ...................................................................................................... 13

6.2 Electrical layout ......................................................................................................... 156.2.1 Hardware description ................................................................................................. 15

General DL37

A-2 6/98 Service Manual ME-704726A

DL37 General


1. Cautionary notes

Warning

When working with the titrator, please comply with the following basic rules !

• Before the instrument is opened, the power plug must be disconnected from the powersupply.

• The service engineer must be familiar with the “Safety instructions for outsiders” of the end-user company.

• Before corrective maintenance work is performed, the titration cell must be removed from theMETTLER TOLEDO KF-Coulometer.

• Only those parts or assemblies specified in the spare parts list may be replaced.

• Karl Fischer reagents are toxic and may be disposed of only as specified by the regulations.

General DL37


2. General information

2.1 Technical changes

Starting January 1996 (or starting with serial number MEB75C10) the DL37 that were delivered havesome major changes in hard- and software.

There are two reasons for these updates:- A few Software features of the DL37 have been changed to comply to GLP regulations. This new Software

is Version 3.1AA. This new software can be used in older instruments as well by replacing the CPU4board, which now has Software Version 3.1AA installed.

- In order to pass the CE tests, changes in Hardware of DL37 had to be done, whereby older instrumentscannot be updated.

2.1.1 Software changes

An external printer with RS interface can be connected to the DL37 in order to have protocols on a nonthermo printer GLP conform print outs.For this, the optional RS interface (ME-105096) has to be installed.You have to configure the DL37 “Function 6”, choose “printer” and set the correct RS settingscorresponding to the external printer.To connect the Printer GA42, the cable ME-51328094 is needed and the dip switch 2 has to be set toposition “on”.The RS setting in “Function 6” has to be 1200 baud / parity: no / stop bit: 2.Please note, that no graphics can be printed out on the GA42. It is however possible to connect a GA42and print out on the DL37 internal printer at the same time, in order to have both GLP print outs andgraphics. If only the internal printer is used and the balance/printer interface is installed, the “Function 6”must be set to “computer”.

2.1.2 Software changes overview

- The print outs are now more complete, in order to be GLP conform.

- An alpha-numerical user ID can be entered.

- The ID# of the DL37 can be changed.

- Re-calculation of a result.

DL37 General


2.1.3 Hardware changes

In order to pass the CE tests, parts like CPU, Transformer and Power line filter had been changed ormodified. The CPU Board is no longer a “CPU 4” type, the new CPU has the designation “CPU5”.Furthermore the “Olivetti” printer has been replaced by a new one from “Seiko”. This printer does not havethe paper lever on top of the printer housing. The missing printer lever with the new instruments makes iteasy to distinguish “CE” and “Non CE” instruments.

Many parts from old and new instruments cannot be mixed. In service cases, parts are always exchangedby the same type. For further information see also the spare parts list which now has two columns for“Non-CE” and “CE” instruments.

2.1.4 Software compatibility

ROM 1 ROM 2 ROM 3 Printer CE GLP

CPU 4 1.7AA 1.7AA 1.7AA Olivetti no no1.9AA 1.9AA 1.7AA Olivetti no no3.1AA 3.1AA empty Olivetti no yes

CPU 5 3.1AA 3.1AA Empty Seiko yes yes

General DL37


3. Exploded view diagrams

3.1 Mechanical layout

12

27

16

8

24

31

30

25

23

Victor M

ahler

DL37 General


3.2 Printer mechanism

22

510

2928

6

13

22

5

2928

13

6

10

33

General DL37


3.3 Electrical layout

0 I

1

2

3

7

14

11

32

4

9

DL37 General


3.3 Cable connections

17

22

1

219

25

12

3

22

20

15

21

16

18

General DL37


4. Spare parts list

Item Designation Part number Part numberNon CE-Version CE-Version

1 Power line filter (New, backward compatible) 51106129 51106129

2 Power switch 105022 105022

3 Power socket (New, backward compatible) 51106130 51106130

4 NiCd battery 105021 105021

5 Thermal printer (Olivetti) 105024 -Thermal printer (Seiko) - 51106131

6 End-of-paper sensor 105025 105025

7 Preamplifier board 105026 105026

8 16-character display 105027 105027

9 CPU4 Processor board 105028 -CPU5 Processor board - 51106133

10 Printer connection board 105030 51106134

11 Power supply board 105031 105031

12 Stirrer motor 105034 105034

13 Printer housing 105041 51106137

14 Transformer 105042 51106135

15 Connection cable, 50-pin (Preamplifier - CPU) 105152 105152

16 Connection cable, 14-pin (CPU - keypad) 105153 105153

17 Connection cable, 20-pin (CPU - printer) 105154 105154

18 Connection cable, 4-pin (Power board - CPU) 105155 105155

19 Connection cable, 3-pin (Preamplifier - CPU) 105156 105156

20 Connection cable, 2-pin(Preamplifier - stirrer) 105157 105157

21 Connection cable (CPU - DO337 socket) 105158 105158

22 Socket, 6-pin 105120 105120

23 Plug, 6-pin 105121 105121

24 Housing 105122 105122

25 Base for titration cell 105159 105159

26 Fuse 1.6 A, slow-blow (set of 3) (see page C3) 18560 185603.15 A, slow-blow (set of 3) 54286 -4 A, slow-blow (set of 5) - 51106155

DL37 General


Item Designation Part number Part numberNon CE-Version CE-Version

27 Keypad 105002 105002

28 Socket 2 mm, red 88549 88549

29 Socket 2 mm, black 88548 88548

30 Plug 2 mm, red 88554 88554

31 Plug 2 mm, black 88553 88553

32 EMI board - 51106143

33 EMI board - 51106139

General DL37


5. Service tools

The following special instruments are needed in addition to the normal tools:

• Socket wrench 5.5 mm for printing unit

• DVM, 3 1/2 digits resolution, impedance > 10 MΩ• Test cable 20 cm with clamps at both ends

• Frequency counter, oscilloscope 50 MHz

• Test instrument (Electrode simulator) ME-105127

DL37 General


6. Instrument layout

6.1 Mechanical layout

The mechanical layout of the METTLER DL37 KF Coulometer comprises the following units:- Titration cell with anode and cathode for the sample- Membrane keypad- Thermal printer for result output- Illuminated display- Interface for electronic balances for the input of sample data- Computer interface (RS-232C) for external acquisition of results and methods (see operating instruc-

tions of DL37 KF Coulometer) or for connecting an external printer.

Thermal printer

Drying tubes of titration cellInner burette(integrated combinationcathode/anode)

Detection electrode(double platinum pin electrode)

Titration cell

Holder of titration cell

Illuminated display:Shows the number of the method,the background level,the status and the data

Membrane keypad

General DL37


The greater part of the electronics of the DL37 KF Coulometer is in the bottom housing section:- Processor board- Preamplifier board- Rectifier board- Interface board- Toroidal-core transformer for power supply- Stirrer motor for magnetic stirrer

All units are interconnected by plug-in connections and can be changed separately.

0 IRS-232C BALANCE

Interface for electronicbalance (option)

Computer interface(RS-232C) (option)

Power switch

DL37 General


6.2 Electrical layout

See exploded view diagrams “Electrical layout” and “Cable connections” (section A) and circuit diagrams(section F).

6.2.1 Hardware description

Power supply connectionThe power transformer is designed for the following input voltages:

Line voltage Voltage range

100 VAC 90 to 121 V120 VAC 103 to132 V220 VAC 198 to 242 V240 VAC 216 to 264 VLine frequency 50/60 HzPrimary circuit fusing fusible cutout 3.15 A slow-blow for 100 and 120 V

fusible cutout 1.6 A slow-blow for 220 and 240 VTolerance of the primary voltages ±10 %

The following voltages are available in the secondary circuit:

Voltage Function Wiring color code

38 V generator voltage 62 V yellow-yellow16 V - 0 V - 16 V IC amplifier supply pink-white-pink / purple-white-purple16 V - 0 V - 16 V Interface, IC amp ±12 V blue-grey-blue24 V printer supply 24 V (“non-CE” only) orange-orange8 V supply for logic 5 V brown-brown

Rectifier boardThe rectifier board is used to generate the direct voltages.The 24 VDC voltage stabilized by controller IC2 is supplied via connector CN-2.3 to the processor boardES-105136. It is used as a driver voltage for the “non-CE” thermal printer. For use in the DL37, the rectifierboard is not fully populated.The 5 V processor voltage is generated by controller IC1 on the rectifier board. It is supplied to the processorboard via connector CN-2.3.

Thermal printer boardThis board is the connecting link between the processor board and the thermal printer. The thermal printerboard incorporates the end-of-paper sensor.

General DL37


Computer and balance interfaceBalance interfaceThe interface for the balance is marked with “balance” (plug-in connection CN2). METTLER PE, PM, AE orAT balances with an RS-232C interface can be connected to the interface. The data format is defined usingswitches S0 -S5 or jumpers.

Switch position: S0, S1, S2 = closedS3, S4, S5 = open

Computer interfaceThe computer interface is marked with “RS-232C” (plug-in connection CN3). The hierarchy corresponds toDCE (Data Communication Equipment), but can be converted to DTE (Data Terminal Equipment) with awired connection. The interface is configured with FUNCTION 6.The clock frequency for both interfaces is generated by the quartz crystal (F = 1.22 MHz).The interface voltage of 17 VAC is rectified on the interface board and stabilized to +12 V and –12 V withIC9 and IC10.Data interchange between the processor board and the interface takes place via plug-in connection CN1.

Display boardThe display comprises- the 16-digit fluorescent display,- the driver circuits IC2 and IC6,- the demultiplexers IC3 and IC5,- character generator (IC1).

The voltage of approx. 60 V needed for the lamp is generated in the DC/DC converter from the 5 V processorvoltage.The CN2 plug-in connection is not used.

Preamplifier boardThe measurement principle of the coulometric KF titration is based on the passage of a controlled constantcurrent through special KF solutions.The relationship – 2 x 96500 coulombs produce the amount of iodine required for reaction with 18 g water(10.71 coulombs/mg H2O) – allows the detection and reliable measurement of even trace amounts ofwater.The stable measurement current needed for the iodine which reacts with water is produced by the field-effect transistor Q8, IC34 and the resistors R29 - R34.The current flows through the cathode, the catolyte and the perforated anode in the anolyte. The processesin the titration cell are detected with the double platinum pin electrode and led to the measuring amplifiervia a stage separated galvanically by an optocoupler. A sinusoidal voltage (IC4/IC17, ROM IC16 and levelconverter IC28) serves as a reference variable.

The titration is started by automatic control. The measurement begins 1 minute after the start ! At the start ofmeasurement (high water content), the double platinum pin electrode carries an alternating voltage of

DL37 General


approx. 600 mV. The end-level voltage with an anhydrous sample is approx. 200 mV. The voltagesgenerated by the transformer and the power supply are rectified and stabilized on the preamplifier board.

The voltage for the current generator -VB and +VB is 62 V via resistor R28. 16 V alternating voltage forIC20, and hence for the measurement evaluation, are used to produce the internal clock frequency ofapprox. 64 kHz.A power supply of –12 V, +12 V is available for the analog circuits.The voltage for the stirrer motor is generated by IC24, amplified by power transistor Q5 and supplied to theCN2 connector.The offset voltage –3.5 V for FET Q8 can be adjusted with potentiometer VR1.

Processor boardThe processor board incorporates the following functions:- Circuitry for control of the preamplifier board- Software for evaluation of the measurement results- Monitor programs for the display and for the keypad inquiry- Control functions for the thermal printer and its control- Real-time clock- Reset circuit- Control of the METTLER DO337 Drying Oven

The clock frequency of 8 MHz is generated by quartz crystal 1. This component contains an oscillator,divider module and buffer and drives the CPU (IC22 MOS version of the Z880).IC16 and IC17 are used for address and data storage. The PLD component (Programmable LogicDevice)(IC14, chip enable) selects the addresses for ROM 1 - ROM 3 and RAM 1 - RAM 2.The ROM chips ROM 1 and ROM 3 contain the monitor programs, the methods, the evaluation programsand the control for the thermal printer (without character set for the thermal printer).The clock frequency of 6 MHz for the thermal printer is generated in quartz crystal 6.CPU2 controls the course of printing and stores the rapidly accumulating data in RAM 3 to avoid data loss.ROM 4 contains the character set for the thermal printer.The heating element drivers are ICs 2 and 4.The motor current for the thermal printer is generated by IC1 and transistor Q2.The speed of the printout is set using potentiometer VR1.

IC12 is the real-time clock for the time and the calendar. The time function as well as the customer'sspecific method configurations and sample data are supported by the NiCd rechargeable battery.RAM 1 and RAM 2 are the memories for the methods, configurations and sample data.

IC32 contains the necessary components for the power ON reset circuit.The data interchange between display and keypad is controlled directly by CPU-IC22.IC19 forms the buffer storage and driver for the data from and to the METTLER DO337 Drying Oven. Thedata are transmitted in machine code.IC19 also generates the frequency for the buzzer BZ (approx. 1 kHz).The stable 5 V voltage for the digital components is generated in IC1 and the 24 V voltage for the motor ofthe thermal printer in IC2 on the rectifier board ES-105136.

General DL37


DL37 Checking

Service Manual ME-704726A 6/98 B-1

Contents Page

1. Checklist maintenance.............................................................................................. 3

1.1 Visual inspection ....................................................................................................... 3

1.2 Parameter check ........................................................................................................ 3

2. Checklist service...................................................................................................... 6

2.1 Visual inspections ...................................................................................................... 6

2.2 Final work steps ........................................................................................................ 8

3. Service mode........................................................................................................... 9

3.1 Cell test .................................................................................................................... 9

3.2 Printer test ................................................................................................................. 11

4. Function test............................................................................................................. 13

Checking DL37

B-2 6/98 Service Manual ME-704726A

DL37 Checking


1. Checklist maintenance

1.1 Visual inspection

Caution

The instrument must not be opened for the following checks.

• Check power cable.

• Check all signal sockets for firm seating and cleanliness.

• Check all screws are tight.

• Check keypad for mechanical damage, distortions, contamination by chemicals and adhesion of themembrane in the corners.

• Check transparency of the display.

• Check burettes and sensors for contamination by chemicals.

• Check the titration cell for contamination.

• Check mounting of the detection electrode and the sensor.

• Check mounting of the titration cell.

• Check overall condition of the plastic housing (dirt, cracks, discoloration, scratches).

1.2 Parameter check

Print out all methods and parameters or inquire manually and note down.

• Separate balance from DL37 KF Coulometer. If a METTLER DO337 Drying Oven is attached, do not dis-connect this.

• Switch on DL37 KF Coulometer.

• Print out methods and parameters with the PRINT key.The printout must be regular and the printed image deep.If the “Size” parameter appears, the battery is discharged (see operating instructions of METTLER DL37KF Coulometer).

Check the stirrer functions

• Press PRE-TIR key. The magnetic stirrer revolves, the background value changes.

• Press the STIRRER key. The magnetic stirrer must revolve.

• Actuate settings 1 - 9 of the SPEED key. The magnetic stirrer must revolve at the specified set speed.

• Press the STIRRER key again. The magnetic stirrer should cease revolving.

Checking DL37


Check method functions

• Press METHOD key.

• Select methods 1 - 5. All numbers 1 - 5 must be capable of being changed.

Check parameter functions

• Select method 2.

• Select “TITR.PARA” and change all parameters.

• Clear at least one parameter with the CLEAR key.

Check alarm and error messages

• Unplug connection of double platinum pin electrode. The message “Electrode open, short” must appear.

• Unplug red plug-in connection of the iodine generator. The message “CURRENT ERROR” must appear.

• Remove paper from printer. The message “Paper empty” must appear.

Perform function test with attached METTLER DO337 Drying Oven

• Select method 3.

• In the menu, change the parameter “Limit;sec” to 20 seconds using the TITR.PARA key.

• Change the parameters “Back;sec?”, “Sampler;se c?” and “Cell;se c?” to 20 seconds.

• In the menu set the parameter “Oven;Te m?” to 100 °C with the TITR.PARA key.

• After the method selection, the temperature in the METTLER DO337 Drying Oven must rise immediatelyand after approx. 5 minut es level out and stabilize around the set value. Overshooting by approx. 10 °Cis admissible.

Check version number

• 000 and the ENTER key causes a brief display (around 2 seconds) of the version number with“Ver. XX.XX.XX.AA”.

Check the weight transfer

• Attach balance with RS-232C interface to the “balance” input of the optional interface. Interfaceparameters: Transmission rate 2400 baud, even parity, 1 start bit.

• Transfer a weight using the SIZE key.

Check computer interface

• Connect RS-232C computer interface to the computer.

DL37 Checking


Check titration cell for leaks

• Load all default values with method 99.

• Select method 2. Start background measurement with the PRE-TITR key. After 1 hour, the backgroundvalue must be < 0.1 µg/s. If this value is not reached, dry titration cell in a desiccator or with a hair dryerand check for leaks.

Check reproducibility (DL37 only)

• Perform three measurements with 250 µL DL37 check solution added using a microsyringe.

Final work steps

• Load customer parameters. Perform sample data transfer.

Checking DL37


2. Checklist service

2.1 Visual inspections

• Check setting of voltage selector is correct.

• Disconnect all attached devices from DL37 KF Coulometer.

• Switch on the DL37 KF Coulometer and select the service program in the menu.

• Start service program by entering “PRE TITR 111 Enter”.

• Print out all methods and parameters.

• Select method 80, a special test method.The text “2 Check <ENTER>” appears in the display.Default values, which can be changed, appear in the display (see table below).Wrong values can have a negative influence on the course of the titration!

Display Value Meaning

Ready Lev. ? 10.0

Short Lev. ? 30.0 Minimum value when Pt electrode short circuited

Open Lev. ? 600.0 Extreme value on break in Pt electrode

Over Titr. ? 150.0 Threshold value on overtitration

Meas Over ? 100.0 Lower threshold value of the measurement

Current ? 20.0 Current through the Pt electrode

Conc. Nbr. ? 4 Not used

Pot Ep Lev. 200 Threshold value for end-point voltage

Para 1 ? 0.0 Not used

Para 2 ? 0.0 Not used

Para 0.0 Not used

Note

Entry of the identical value allows exit from the hidden functions. A beep confirms return to the normalmode.

The parameters can be printed out with the PRINT key.

Exit the service mode by entering RESET.

Note

If no parameters have been changed, the DL37 is in the operational readiness condition.

DL37 Checking


If parameters have been changed, the default values must be entered.The following procedure sets all parameters to the default values:

• Select “Method 99 Enter”.

• Switch off instrument.

• Wait at least 10 seconds.

• Switch on instrument again.

All methods and parameters now have the default setting.

Note

Reenter the customer’s values for the methods and all other parameters (see operating instructions of DL37KF Coulometer).

Use of the test instrument

A titration routine can be reconstructed with the aid of the test instrument (electrode simulator):

• Unplug generator connector and platinum sensor.

• Attach test instrument.

• Turn potentiometer completely to the right.


• Press PRE-TITR key.

• Select FUNCTION 7.

• Press ENTER key. The display shows: Pot,mV.

• Set voltage value on potentiometer to 350 mV for Software Version 3.1AA.Set voltage value on potentiometer to 250 mV for Software Version 1.7AA / 1.9AA.No end point may be detected as this voltage does not correspond to the end-point voltage of 200 mV.

• Set voltage to 200 mV by slowly turning the potentiometer. The end of the titration is signalled by a beep.

• By slowly turning the potentiometer further, the voltage becomes less. At a voltage of 150 mV, thewarning “Over Tit” appears.

Summary

If the DL37 KF Coulometer reacts as described above, with the appropriate values, the hardware of theinstrument is functioning properly.

Possible error sources if behavior different from above:

• Major leak (background level) owing to water in silicone grease

• Dirty titration cells

• Impure reagents

The visual inspection is performed in the same manner as that for the maintenance check, see section 1.1.

Checking DL37


2.2 Final work steps

Reread error codes in the operating instructions of the DL37 KF Coulometer.

• Perform the parameter check, section 1.2, before opening the instrument. In many cases, thismaintenance check and any error codes allow the error to be localized.

• Measure all voltages.

• Perform printer test, see service mode chapter B3.

• On completion of the maintenance check, disconnect the power plug.

• Close the DL37 KF Coulometer and reconnect to power supply.

• Switch on the DL37 KF Coulometer.

DL37 Checking


3. Service mode

The service mode comprises two main tests:

- the cell test and

- the printer test.

In the cell test, the water tightness of the titration cell, the measurement potential and the condition of thereagents are checked.The printer test is a function test of the built-in thermal printer.

3.1 Cell test

Use of hidden test functions: The DL37 KF Coulometer is in the standby mode.

• Press PRE-TITR key. All entries must be confirmed by pressing the ENTER key.

Entry Value Meaning

000 e.g. 87AA ROM version (approx. 2 seconds)

000–.0 µg/sec Stability of the current change shows whether titration cellis leaking. The value should be within the set backgroundvalue.

0002.– . 2 Drift & level display In Function 7 with 2x ENTER

000–.1 Stability of the background Unstable values indicate exhausted reagents.measurement to 3 places

000–.6 Generator current Value of the last background measurement.Value should be within the set background value(e.g. 0.1 µg/sec).

000–.7 Blocks the display Segment test

Checking DL37


NoteWith Software Version 1.7AA / 1.9AATo quit the above test routine or to proceed to the next step, enter the following key sequence:

Example

Reset000–.1Enter A repeated beep of the built-in buzzer confirms the normal mode.

Example

000–.0Enter The stability is displayed.000–.0Enter Display returns to the normal mode.

With Software Version 3.1AATo quit or to proceed into the next step enter the new key sequence:

Example000–.0Enter The stability of the current generator is displayed.000–.1Enter The stability of the back ground level is displayed.

Cleaning of the cell and replacement of reagents are described in detail in the DL37 KF Coulometeroperating instructions.

Note

Extended measurement possibility in the function for measurement of the water tightness of the titrationcell, the functioning of the Pt sensor and the condition of the two reagents:

Example

000–.2EnterFunction 7Enter Pot., mVEnter Display of the background value and the measurement potential

DL37 Checking


Note

With Software Version 1.7AA / 1.9AA

To quit the above test routine or proceed or to go to the next step in the routine, enter the following keysequence:

Example

Reset000–.2Enter A repeated beep of the built-in buzzer confirms the normal mode.

With Software Version 3.1AAWith the following sequence skip to the next step.To go to the next step in the routine, enter the following key sequence.

Example

000–.2Enter Drift and Background Level is displayed.000–.1Enter Stability of the Background Levels is displayed.

3.2 Printer test

CPU4 and Software Version 1.7AA / 1.9AA / 3.1AAThe quality of the printout and the uniformness of the printing image is tested or adjusted in the printer test.

• Open DL37 KF Coulometer.

• Place housing cover on right.

• Switch DIP switch No. 4 on the processor board to ON.

• Ensure that the printer paper is inserted properly.

• Briefly press reset knob on processor board.The thermal printer outputs a neat test printout of length around 30 cm within approx. 45 seconds.

• On completion of the printer test, reset DIP switch No. 4 to OFF.

If the thermal printer outputs not a neat test printout, the printer frequency must be checked and adjusted(See chapter D2.2)

Checking DL37


CPU5 and Software Version 3.1AAThe quality of the printout and the uniformness of the printing image is tested or adjusted in the printer test.


• Place housing cover on right.

• Switch DIP switch No. 4 on the processor board to ON.

• Ensure that the printer paper is inserted properly.

• Briefly press reset knob on processor board.

• On completion of the printer test, reset DIP switch No. 4 to OFF.

If the thermal printer outputs not a neat test printout, the printer frequency must be checked and adjusted(See chapter D2.3).

DL37 Checking


4. Function test

Perform function test


All segments of the illuminated display must light up.

• Press PRE-TITR key.

The stirrer must revolve.

• Press STIRRER key. The stirrer should cease revolving.

• Press STIRRER key. The stirrer must revolve again.

• Press SPEED key. Enter numeric values 1 to 9 one by one. The stirrer must revolve faster with increasingnumeric value, but should not touch the titration cell at the highest speed (setting 9).

• Press PRINT key.A paper advance of 7 lines must start. The printout should show no streaks.

• Select a method.

• Press PRINT key. The method parameters are printed out. The print quality of the printout must be good.The numbers must not be squabbled. The paper should not streak at the side.

• Take paper roll out holder.The message “Paper out” must be outputted.

Check data transmission

Without balance connection

• Press SIZE key.

• Enter a sample weight manually.

• Enter two different weight data sets. The built-in tare calculator must be able to calculate the net weight.

With RS interface and AE, AT, PJ, PM or PE balance attachment

• Connect balance to interface.

• Press SIZE key.

The sample weight is now read in and must appear on the display.

Checking DL37


TroubleshootingDL37

Service Manual ME-704726A 6/98 C-1

Contents Page

1. Fuses ....................................................................................................................... 3

2. Test points ................................................................................................................ 4

2.1 Processor board ........................................................................................................ 4

2.2 Preamplifier board ..................................................................................................... 5

2.3 Power supply board ................................................................................................... 5

2.4 Interface board .......................................................................................................... 6

3. Troubleshooting ........................................................................................................ 7

Troubleshooting DL37

C-2 6/98 Service Manual ME-704726A

TroubleshootingDL37


1. Fuses

The line-side fuse values:

AC Voltage Fuse Hz

V 90 - 121 V 3.15 A, slow-blow 50/60V 103 - 132 V 3.15 A, slow-blow 50/60V 198 - 242 V 1.6 A, slow-blow 50/60V 216 - 264 V 1.6 A, slow-blow 50/60

Various semiconductor fuses are on the boards.They are marked on the circuit diagrams with“EMF”. Replacement is possible only in the factory.

Connection to METTLER DO337 Drying Oven

Line voltage

Voltage selector

Flat screwdriver

Voltage selector

Fuses



2. Test points

The following sections show the tables of all test points for the processor, the preamplifier, the display, thepower supply and the interface boards.

2.1 Processor board

Test points at the connectors

Test point Target value Tolerance

CN9 Pin A15-A16 17 VAC ±10 %CN10 Pin 1-2 17 VAC ±10 %CN10 Pin 1-3 17 VAC ±10 %CN10 Pin 2-3 35 VAC ±10 %CN8 Pin 1-5 5 VDC ±5 %CN8 Pin 3-4 24 VDC ±5 %

The keys of the membrane keypad can be tested at IC22 using an oscilloscope. Reference point is CP0.

Test point Signal Target value Tolerance Remarks

JP1 GND2 0 V Reference point for 24 VJP5 GND1 0 V Reference point for 5 VCP0 GND test point 0 V Reference point for measurementsJP3 Clock frequency 8 MHz Reference to CP0CP2 Clock frequency 4 MHz Reference to CP0IC22 Pin 1 3, 6, 9, –, RESET keys Reference to CP0IC22 Pin 2 2, 5, 8 keys Reference to CP0IC22 Pin 4 PRINT key Positive pulseIC22 Pin 5 0, 1, 4, 7 Negative pulse trainIC22 Pin 6 CLEAR, ENTER keys Reference to CP0IC22 Pin 7 STIRRER key Reference to CP0IC22 Pin 8 SIZE, RESULT keys Reference to CP0

TITR.PARA, METHOD Reference to CP0Battery 5.0 V With DL37 switched on

2.5 V With DL37 switched offIC4 Pin 12 Pulse train On printer start

TroubleshootingDL37



Anode D3 –12 VDC 12 VDC 5 % Analog voltageAnode D4 +12 VDC 12 VDC 5 % Analog voltageCathode D3 0 VDC Reference GNDAnode D10 +12 VDC 12 VDC 5 % Analog voltageAnode CP5 –5 VDC 5 VDC 5 % Analog voltageCathode CP5 0 VDC Reference GND–VB - +VB 62 VDC 62 VDC ±5 V Driver voltageCP2-CP4 2.5 V 2.5 V 10 mV See adjustment 2, section D,

chapter 2.1CP2-R41 –2.5 VDC –2.5 V ±0.75 V See adjustment 1, section D,

chapter 2.1IC26/6 -cath. D3 25 Hz sinus 1.0 V 0.6 V -1.5 V Electrode voltage, section B,

chapter 2.1JP1-cath. D3 5 MHz Clock frequencyJP2-cath. D3 100 kHz Clock frequency


Test point Target value Remark / Tolerance

CN2 Pin 1-2 See stirrer test, section B, chapter 1.2.

CN3 Pin 1-2 17 VAC ±10 %CN3 Pin 1-3 17 VAC ±10 %CN3 Pin 2-3 35 VAC ±10 %CN4 Pin 1-2 35 VAC ±10 %CN4 Pin 3-4 16 VAC ±10 %CN4 Pin 3-5 16 VAC ±10 %

2.3 Power supply board

Test point Target value Tolerance Remark

CN8 Pin 1-5 5 VDC ±5 % On the processor boardCN8 Pin 3-4 24 VDC ±5 % On the processor board

2.2 Preamplifier board




Anode D2 –12 VDC 12 VDC 5 % Interface voltageCathode D1 +12 VDC 12 VDC 5 % Interface voltageCathode D2 0 VDC GNDIC2 Pin 23 1.22 MHz 5 V Clock frequencyIC2 Pin 23 GND


Test point Target value Tolerance

CN1 Pin A15-A16 17 VAC ±10 %CN3 Pin B15-B16 17 VAC ±10 %

Additional measurements of the data transmission can be performed with the break box directly atconnectors CN2 and CN3.

2.4 Interface board

TroubleshootingDL37


3. Troubleshooting

The following error messages are shown in the display of the DL37 KF Coulometer:

Error message Possible cause Rectification

No display Voltage selectorFusesPoor contacts Check all plug-in connections.Analog board faulty Measure voltages.Digital board faulty Measure voltages.Power supply board faulty Measure voltages.

ADP Error! Plug-in connection Check connection cable.Error in ADP Check all plug-in connections.

Measure voltages.

Current Error! Current anode short circuited Check anode for short circuit.Analog board faulty Check analog board with electrode tester.

Elect Open! Break in electrode cable Check detection electrode, cable andconnector.

Elect Short! Electrode tips short circuited Check detection electrode, cable andconnector.

NoteIt is important to perform a simulated titration with the electrode tester as the first step. Many errormessages can be caused by both a fault in the system and an error in the application (e.g. exhaustedchemicals).Additional error messages, see operating instructions of DL37 KF Coulometer.

Check stirrer motor and power supply


• Disconnect stirrer motor cable at connector CN2.

• Attach digital voltmeter to connector CN2.

• Switch on stirrer voltage with the STIRRER key.

Voltage value with SPEED 1 key: 0.6 - 0.8 V





RepairsDL37

Service Manual ME-704726A 6/98 D-1

Contents Page

1. Corrective maintenance ............................................................................................ 3

1.1 Changing the preamplifier board .................................................................................. 3

1.2 Removing the thermal printer ....................................................................................... 4

1.3 Removing the magnetic stirrer motor ............................................................................ 5

1.4 Changing the display board ........................................................................................ 6

1.5 Dismantling the membrane keypad .............................................................................. 7

1.6 Replacing the power transformer .................................................................................. 8

1.7 Changing the voltage selector ...................................................................................... 9

1.8 Changing the power switch ......................................................................................... 9

1.9 Changing the power line filter ...................................................................................... 10

1.10 Changing the rectifier board ........................................................................................ 11

1.11 Changing the interface board and processor board ........................................................ 11

2. Checking and calibrating the boards .......................................................................... 12

2.1 Calibrating the preamplifier board ................................................................................ 12

2.2 Adjusting the processor board (CPU4) ......................................................................... 15

2.3 Adjusting the processor board (CPU5) ......................................................................... 16

Repairs DL37

D-2 6/98 Service Manual ME-704726A

RepairsDL37


1. Corrective maintenance

1.1 Changing the preamplifier board

• Unscrew the four screws (1) at the rear of theinstrument next to the heat sink.

• Slowly and carefully pull out rear panel halfwayapprox. 5 cm.

• Undo the plug-in cable connections at connec-tors CN5, CN1, CN3 and CN4 in that order.

• Now take out preamplifier board completely andchange.

• Perform installation of the preamplifier boardES-105132 in reverse order. Ensure the4 screws are firmly tightened.

• Adjust new preamplifier board, see section D,chapter 2.1.

• Reinstall metall shielding

1 1

Repairs DL37


1.2 Removing the thermal printer

For replacement of the thermal printer, do not openDL37 KF Coulometer completely.

• Remove printer paper (3).

• Unscrew the two screws (2) of the printer hous-ing (4).

• Lift up printer housing slightly at rear and pressforward.

• Take off printer housing.

• Undo four nuts (5) and carefully remove theretaining plate.

• Remove printer (6).

• Unplug flat cable from intermediate board.

• Install in reverse order.

• Adjust printing quality as described in chapterD2.2 or D2.3.

2

5

6

3

5

5

6

4

4

5

3

RepairsDL37


1.3 Removing the magnetic stirrer motor

• Remove titration cell from its holder.

• Unscrew two screws at holder.

• Remove holder of titration cell.

NoteThe mounting plate of the magnetic stirrer motormust not be removed!

• Open DL37 KF Coulometer at base.

• Withdraw stirrer motor cable.

• Unscrew two hex socket-head screws (2 mm) ofthe magnet support plate.

• Loosen magnet support plate from the motorshaft and remove.

CautionThe magnetic force is active! The magnet will splin-ter if loose objects fall on it.

• Unscrew the four screws of the motor mountingplate.

• Take out the magnetic stirrer motor from above.

• Install new magnetic stirrer motor.

• Mount magnet support plate and align flush withthe end of the motor shaft.

• Tighten screws.

• Installation in reverse order.

11

2

Repairs DL37


1.4 Changing the display board



• Disconnect all cable connections to top half ofDL37.

• If present, disconnect ground connection of thedisplay board.

• If present unscrew and remove metall case fromdisplay.

• Unscrew the metal plate with the display.

CautionThe plate on the display board must be on the sideof the ground connection.

• Remove display.

• Clean front glass if necessary.

• Install new display board in reverse order.

RepairsDL37


1.5 Dismantling the membrane keypad



• Disconnect all plug-in cable connections to tophalf of DL37 KF Coulometer.

Dismantling the membrane keypad• Remove membrane keypad.

• Carefully remove any residual adhesive fromsupport surface of membrane keypad at housingwith ligroin.

• Clean the front glass if necessary.

Installing the membrane keypad• Remove both protective films at the rear of the

membrane.

• Align keypad membrane flush at bottom and atone side and stick on.

• When sticking on membrane keypad, pressdown carefully.

• Pressing and smoothing down eliminates airbubbles.

Repairs DL37


1.6 Replacing the power transformer


• Open the DL37 KF Coulometer.

• Disconnect plug-in cable connection CN1 at rec-tifier board.

• Disconnect plug-in cable connection CN4 atpreamplifier board.

• Disconnect plug-in cable connection CN11 atprocessor board.

• Unsolder the transformer connections of the linevoltage selector.

• Unscrew transformer from bracket.

• Screw on new transformer.

• Reconnect plug-in cable connections.

• The plug-in cable connections CN10 and CN11are implemented in parallel and hence inter-changeable.

• Solder on transformer connections at line voltageselector as shown in the wiring diagram. (Seechapter D1.9)

• Reassemble in reverse order

RepairsDL37


1.7 Changing the voltage selector

0I



• Unsolder connections from line voltage selectorand power supply input.

• Press the plastic latches together and removealong with the line voltage selector.

• Install new voltage selector.

• Solder on connections as shown in the wiringdiagram. (See chapter 1.9)

1.8 Changing the power switch



• Disconnect the four cables at the power switch.

• Press the plastic latches at the power switch together and remove along with the power switch.

• Solder on connections as shown in the wiring diagram.

Repairs DL37


1.9 Changing the power line filter



• Unscrew the eight screws on rear panel.

• Unscrew the four screws on baseplate.

• Unsolder the transformer connections at line vol-tage selector.

• Lift up transformer bracket and unscrew powerline filter.

• Reinstall power line filter.

• Solder on power supply connections as shown inthe wiring diagram.

• Reassemble instrument in reverse order.

T blue

2 PS blue 5 PS brown

OUT PF blue OUT PF brown

IN PF blue IN PF brown

green/whiteGround

TPSPF

===

TransformerPower switchPower line filter

T yellow T white

4 PS brown T orange T red1 PS blue

RepairsDL37


1.10 Changing the rectifier board



• Disconnect plug-in cable connections CN1 andCN4 at the rectifier board.

• Unscrew two screws on baseplate.

• Change rectifier board.

• Reconnect the two plug-in cable connections.

1.11 Changing the interface board and processor board



• Unscrew two screws at side of DL37.

• Remove interface board.

• Disconnect all plug-in cable connections of pro-cessor board.

• Unscrew two screws at processor board.

• Take out the processor board.

• Insert new processor board.

• Insert new interface board.

• Screw on interface board.

• Screw on processor board.

• Connect all plug-in cable connections.

• Adjust processor board.

Repairs DL37


2. Checking and calibrating the boards

NoteThe replacement boards are adjusted by the manufacturer. The adjustment after replacement is anecessary check.

2.1 Calibrating the preamplifier board

Working aids• DVM, 3 1/2 digits/impedance >10 MΩ• Test instrument ME-105127• Short test cable with clamps at both ends

Procedure• Switch off DL37 KF Coulometer.

• Attach the test instrument in place of the titration cell.

• Undo the four screws at the rear of the instrument next to the heat sink.

• Slowly and carefully pull out rear panel halfway.

• Take out preamplifier board halfway.

• Disconnect connector CN1. The other connectors must remain plugged in.

Potentiometer20 kΩ lin.13

1µF630 V

rot / red

weiss / white

Ω1 / 5 W 0,1%50 ppm1

3

Schematic of test instrument

RepairsDL37


Preamplifier board

Offset current generator adjustment• Attach the DVM to test point CP2 (minus side).

• Attach resistor R41 (positive voltage).


• Allow the DL37 KF Coulometer to warm up for 15 minutes.

• The voltage should reach a value between –1.5 V and –3.5 V.

Voltage outside range –1.5 V to –3.5 V:

• Adjustment with potentiometer VR1.

Adjustment of the potentiometer is very sensitive.

VR1 R41 VR42

Repairs DL37


Reference voltage adjustment• Switch off the DL37 KF Coulometer.

• Attach DVM between test point CP4 (plus) and CP2 (minus).


The voltage should be approx. 0 mV.

• Switch off the DL37 KF Coulometer.

• Short circuit the test points CP5 and CP6 with a short test cable.

The voltage on the DVM should be 2.5 V ± 1.0 mV.

• Adjust the voltage with potentiometer VR2.


• Disconnect shorting cable and DVM.

Checking the safety circuit• Attach cable of electrode test instrument in place of titration cell.

• Connect test point CP2 and anode side of diode D8 with a test cable.


The safety relay RY1 must switch audibly.


• Disconnect cable connections.

Checking the measurement current• Attach DVM to connection of the current generator.

• Connect test points CP5 and CP6 with a test cable.

• Connect test point CP2 and anode side of diode D8 with a test cable.

NoteEnsure short cable connection !

• Switch on the DL37 KF Coulometer.The voltage at the measuring resistor should be 40 mV ± 0.5 mV.

If this voltage is not found:

- Check reference voltage. (See “Reference voltage adjustment”)

- Replace preamplifier board.

RepairsDL37


2.2 Adjusting the processor board (CPU4)

Real time clock adjustment

Instruments needed:Frequency counter or oscilloscope

• Set frequency counter to time measurement.

• Connect frequency counter between CP1 and CP0 (ground).

• Adjust trimmer VC1 until the display of the frequency counter shows 61035.16 ns or 16.384 kHz.

Printing quality adjustment• Switch off the DL37 KF Coulometer.

• Set DIP switch No. 4 to ON.


Printer starts.

Printout is interrupted with RESET key.

• Press RESET key again.

Printer starts.

• Measure time for all characters to be printed out.

Time should be around 45 seconds.

Print quality of printout is not perfect or image is squabbled:

• Adjust potentiometer VR1.

VC1 Real Time Clock adjustment VR1 Printer adjustment

Repairs DL37


2.3 Adjusting the processor board (CPU5)

Real time clock adjustment

Instruments needed:Frequency counter or oscilloscope

• Set frequency counter to time measurement.

• Connect frequency counter between CP1 and CP0 (ground).

• Adjust trimmer VC1 until the display of the frequency counter shows 100.00 µS or 100 kHz ± 0.200 kHz.

Printing quality adjustment• Switch off the DL37 KF Coulometer.

• Set DIP switch No. 4 to ON.

• Switch on the DL37 KF Coulometer.Printer starts.Printout is interrupted with RESET key.

• Press RESET key again.

Printer starts.

Print quality of printout is not perfect or image is squabbled:

• Connect frequency counter to CP5 and CP0 (Ground)

• Adjust potentiometer VR1 to a reding of 100.000 kHz ± 0.200 kHz.

VC1 Real Time Clock adjustment VR1 Printer adjustment

Service Bulletins

Service Manual ME-704726A 6/98 E-1

DL37

Contents section E Date of issue

Is my service manual really up to date?At the bottom right of the title page you will find the date of issue. If you know the date of the latestedition, you can thus see whether your service manual is up to date.

If this is not the case, the latest service bulletin has not been filed. (The service bulletins represent acontinuous supplement to the service manual and keep it up to date.)

The service bulletin always includes a new title page for the service manual, new pages and pages tobe exchanged, as well as a new contents page for section E. All these documents have the same,latest date of issue at the bottom of the page.

First edition of the “METTLER DL37 KF Coulometer” service manual: March 1992 (03/92)

This service manual replaces the service manual ME-704726, edition March 1992.

There are no Service Bulletins at present

Service Bulletins

E-2 6/98 Service Manual ME-704726A

DL37

Service Manual ME-704926 6/98 F-1

DL37 Data section

Contents Page

Overall diagram ES-105130 .................................................................................................. 3

Wiring diagram ES-105133 ................................................................................................... 5

RS232C-Interface board ES-105134 ...................................................................................... 7

Power supply board ES-105136 ............................................................................................. 9

Display board ME-105027 ..................................................................................................... 11

Power supply board ME-105031 ............................................................................................ 13

RS232C-Interface board ME-105096...................................................................................... 15

Data section DL37

DL37 F-3

METTLER TOLEDO reserves all rights in this document and in the subject thereof. By accep-tance of the document the recipient acknowledges these rights and undertakes not to publishthe document nor the subject thereof in full or in part nor to make them available to any thirdparty without METTLER TOLEDOs prior express written authorisation nor to use it for anypurpose other than for which it was delivered to him.

Overall diagramES-105130

Data section DL37

DL37 F-5

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Data section DL37

DL37 F-7


RS232C-Interface boardES-105134

Data section DL37

DL37 F-9


Power supply boardES-105136

Data section DL37

DL37 F-11


Display boardME-105027

Data section DL37

DL37 F-13


Power supply boardME-105031

Data section DL37

DL37 F-15


RS232C-Interface boardME-105096

Data section DL37

Documents

DL37_SM_e_710142