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KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen-Frommern
E-Mail: info@kern-sohn.com
Tel: 0049-[0]7433- 9933-0
Fax: 0049-[0]7433-9933-149
Internet: www.kern-sohn.com
GB
Service Manual
Electronic Moisture Analyzer
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KERN MLS 50-3…N
Version 1.2 10/2008
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CONTENTS
1. Keyboard Description .......................................................................................... 3
2. Troubleshooting................................................................................................... 4
3. Error Messages ................................................................................................... 5
4. Factory Menu (service menu).............................................................................. 6
4.1 How to enter the service menu..................................................................... 6
4.2 Description of factory parameters................................................................. 7
5. Factory Calibration .............................................................................................. 9
6. Temperature Calibration.................................................................................... 10
7. Linearity Correction ........................................................................................... 11
7.1 Linearity correction (single-stage) .............................................................. 11
7.2 Parabolic linearity correction ...................................................................... 12
7.3 Linearity correction (multi-stage) ................................................................ 13
7.4 Changing linearity factors........................................................................... 14
8. Off-Center Load Adjustment.............................................................................. 15
9. Printout of Factory Parameters.......................................................................... 16
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1. Keyboard Description
Key Function
• Switch machine on/off
• Change display during drying process
• Start/Stop drying
• Cancel an entry
• Leave menu
• Arrow keys for navigation in menu
• Change the value of a parameter
• Data export to external device
• Confirm/save settings
• Tara key scales zero digits
• Invoke user menu (drying parameter setting)
• Invoke user menu
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2. Troubleshooting
1 Unit does not turn on Check mains cable
Check fuses
Check cable connections
Problem on power board
Problem on display board
Problem on main board
2 Balance is weighing but is
unstable
Mechanical damage
Pan rubbing against case or not installed correctly
Air drafts or vibration or unstable table
Not good parameters for the working conditions
Dirt inside the measurement system or inside the coil
3 No zero point after
turning on the balance
Pan needs to zero
Mechanical damage
4 Balance shows wrong
weight
Wrong calibration
Mechanical damage to weighing mechanism
Pan not installed correctly
Off center load error
Dirt inside the measurement system
5 Off center load error Check if the horizontal stat is being
kept mechanical damage
6 Intense creeping (drift) Mechanical damage
Dirt inside the measurement system
7 Linearity error Linearity correction
Mechanical damage
9 No communication
between balance and PC
Wrong parameter
Check connection RS-232 to PC
Wrong interface cable
10 Time and date does not
work
Check voltage TTL 2 Hz (0/+5V DC on measuring point SQW
Problem on main board
Batteries are damaged
11 Display shows program
number, no function
Quartz does not work
Processor damage
Check tension RST (reset) “1” +5V and exchange main board
when RST does not work
12 Outside maximum range Mechanical damage
Check voltage on measuring resistor
13 Balance works OK but
drying is not correct
Check parameters and mode selected
Check samples are not hitting the temp. sensor
Check temperature of chamber
Check lamps
14 Temperature of chamber
is incorrect
Recalibrate temperature sensor
Temperature sensor damaged
Lamp circuits damaged
15 Heating lamps will not
turn on at any time
Check lamps
Check wiring of lamps
Temperature sensor
16 Lamps will not turn off Damaged temp. sensor
Recalibrate temp. sensor
Lamp control circuits damaged
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3. Error Messages
Fault messages Error
number
Description
Error of control sum 1.1 Error data transfer
Error A/D 1.2 Error A/D converter
Overcrossed range 2.1 Outside maximum range
Overcrossed range 2.2 Outside maximum range
A/D Null 2.3 Error A/D converter
A/D Full 2.4 Error A/D converter
Tare/zero above the range 2.5 Outside of weighing range
Tare above the range 2.6 Outside of taring range
Result > 10% Max 2.7 Result > 10 %
Result > 4% Max 2.8 Load on weighing plate too heavy
Difference > 1% Max 2.9 Difference between cal. weight
stored/current cal. weight > 1%
Sample mass < 20 mg 2.10 Sample < 20 mg
Sample mass above the
range
2.11 Sample out of set range
Above the range 3.1 Value of parameter outside
Faulty value 3.2 Value of parameter outside
Incorrect password 3.4 Wrong password
Error of notice 4.1
Parity error 4.2
Table error 4.3
Suspended transmission
CTS
4.4
Suspended transmission
XOFF
4.5
Error data transfer
Incorrect date 5.1 Wrong data
Overcrossed time 6.1 Timeout
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4. Factory Menu (service menu)
Contents of the factory menu are parameters needed to start, settings and
regulations.
4.1 How to enter the service menu
Open the housing and set jumper „JP1“ on main board 172xxx.PCB to access the
service menu.
Plug the balance into the power outlet and enter service menu.
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4.2 Description of factory parameters
Press the ON/OFF key (main switch) to turn on the balance
Enter main menu
Set index next to parameter
P0 Factory
Enter submenu P0 Factory
Parameter
number
Parameter name
Description
P0 01
Factory deff Delete all settings in balance and load program
primal settings
» Factory setting (Reset) / PLEASE NOTICE you
have to set all parameters new!!!
P0 02
Balance Id Change factory number (serial number)
P0 03
Full scale
(scale capacity)
Scale capacity (max) = weighing range +9
divisions: e.g. max range 50,09g
P0 04
Div Reading precision (resolution), e.g. 0.001
P0 05
Ext. cal. mass Value of external calibration weight [g], e.g. 50.0g
P0 06
Autozero range Range of autozero function (possibility to change
value from 0.1d to 10.0d) Normal 12= 3.0 d
P0 07
Autozero delay Time of autozero (possibility to change value from
0.2s to 3.0s) Normal 6= 2.0 s
P0 08
Stable range Stable range of measuring results (possibility to
change value from 0.1d to 10.0d)
Normal 11= 2.0 d
P0 09
Stable speed Time to define stable measuring results (possibility
to change value from 0.2s to 3.0s)
Normal 6= 2.0 s
P0 10
Filter range Digital filter (possibility to change value from 1d to
10000d)
Normal 5 – 20 d
P0 11
Show A/D div Value of A/D converter (of the load)
P0 12
Show A/D T1 A/D value of temperature sensor in the coil
P0 13
Show A/D T2 A/D value of temperature sensor in the drying
chamber
P0 14
Factory cal. Starts factory calibration with external calibration
weight
P0 15
Factory T cal. Starts calibration of the temperature sensor inside
the drying chamber
P0 16
Linear. corr. Starts linearity procedure with external weights.
You can inscribe max. 16 points of linearity.
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P0 17
Temp. corr. Starts temp. compensation in a room with
regulated temperature (range ± 1°C). Correction is
done in temp. 18°C up to 28°C.
The parameters/values are stored after doing
temperature compensation (parameters P0 27, P0
28).
P0 18
Start div Preload (with pan) - balance find it automatically
P0 19
Cal. factor Calibration factor during factory calibration
P0 20
Start div f. Preload after correction
P0 21
Cal. factor f. Not documented
P0 22
T. max Not documented
P0 23
Start T Not documented
P0 24
Factor T The factor during the temperature compensation
P0 25
Start f. T Not documented
P0 26
Factor f. T The factor during temperature compensation after
filtering
P0 27
1’st point T First temperature correction set by 18°C
P0 28
Start T 2 Not documented
P0 29
Factor T 2 Factor during temperature compensation 2’nd point
P0 30
Start f.T2 Not documented
P0 31
Factor f. T 2 The factor during temperature compensation after
filtering 2’nd temperature point
P0 32
2’nd point T Second temperature correction set by 28°C
P0 33
Temp. Z factor Temperature compensation factor of zero
P0 34
Temp. S factor Temperature compensation factor of sensitivity
P0 35
Lin. points
Lin. value 1
Lin. factor 1
Lin. value 2
Lin. factor 2
Lin. value 3
Lin. factor 3
.
.
.
.
.
.
.
.
P0 64
Lin. value 15
P0 65
Lin. factor 15
P0 66
Lin. value 16
P0 67
Lin. factor 16
Those parameters are stored after doing linearity
correction. These parameters (the stored values)
can be changed manually (max. 16 points).
Here you can change the linearity factor manually
also without doing the linearity correction by using
external weights.
P0 68
Lin. factor A Parabolic linearity factor
P0 69
Lin. factor B Parabolic linearity factor
P0 70
Up/Down par. Printout of factory parameters, printout of moisture
analyzer parameters or receipt of moisture
analyzer parameters
P0 71
Stack info. Information about the stored settings when the
moisture analyzer will be started
P0 72
Bootloader Select this parameter for software download /
update
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P0 73
Fat perc. fun Function of large content in user menu
0= disabled (function not available in user menu)
1= enabled (function available in user menu)
P0 74
Heater type Type of heating element in moisture analyzer:
0= Halogen
1= IR
P0 75
Cor, factor T Service parameter for characteristic of drying
chamber thermometer
5. Factory Calibration
Enter submenu P0 Factory and press
key to start factory calibration P0 14
Return to weighing mode:
Press the ESC-key repeatedly until the query ”SAVE?“ appears. Confirm query by
pressing the PRINT-key or reject it by pressing the ESC-key.
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6. Temperature Calibration
We recommend checking the temperature value of the device from time to time. Before you
do this, allow the device to cool down for at least 3 hours after the last heating phase. Push
the probe into the designated hole in the disk. Push the probe as closely as possible to the
thermal sensor of the MLS. The temperature is measured at two points and it is possible to
correct it at both temperature points.
Procedure using temperature calibration set MLB-A11
Select by using the arrow keys (Ð Ï) „04 Temp.cal“
Press Î key
Temperature calibration starts.
Setup29.12.04 Setup
Setup
29.01.08
Setup
Temperature calibration
1 point 14:59
Temperature calibration of first point will take 14.59
min after which you will hear an acoustic signal.
Now you can correct the temperature value (e.g.
25/24), as required, by using the arrow keys (Ð Ï).
Setup
29.01.08
Setup
Temperature calibration
1 point 00:00
Setup
29.01.08
Setup
Temperature calibration
Set temp. value [°C]
25
Setup
29.01.08
Setup
Temperature calibration
Set temp. value [°C]
24
To import the temperature values, press the PRINT-
key; temperature calibration for the second point will
be started.
Setup
29.01.08
Setup
Temperature calibration
2 point 14:59
Temperature calibration of first point will take 14.59
min after which you will hear an acoustic signal.
You can now correct the temperature value (e.g.
120/122), as required by using the arrow keys (Ð Ï).
To import the temperature values, press the PRINT-
key.
Setup
29.01.08
Setup
Temperature calibration
2 point 00:00
Setup
29.01.08
Setup
Temperature calibration
Set temp. value [°C]
120
Setup
29.01.08
Setup
Temperature calibration
Set temp. value [°C]
122
Return to weighing mode:
Press the ESC-key repeatedly until the query ”SAVE?“ appears. Confirm query by
pressing the PRINT-key or reject it by pressing the ESC-key.
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7. Linearity Correction
7.1 Linearity correction (single-stage)
Enter submenu P0 Factory
Set index next to parameter P0 16
and press the
Î button
Return to weighing mode:
Press the ESC-key repeatedly until the query ”SAVE?“ appears. Confirm query by
pressing the PRINT-key or reject it by pressing the ESC-key.
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7.2 Parabolic linearity correction
Enter submenu P0 Factory
Set index next to parameter P0 16
and press the
Î button
Return to weighing mode:
Press the ESC-key repeatedly until the query ”SAVE?“ appears. Confirm query by
pressing the PRINT-key or reject it by pressing the ESC-key.
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7.3 Linearity correction (multi-stage)
Enter submenu P0 Factory
Set index next to parameter P0 16
and press the
Î button
Return to weighing mode:
Press the ESC-key repeatedly until the query ”SAVE?“ appears. Confirm query by
pressing the PRINT-key or reject it by pressing the ESC-key.
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7.4 Changing linearity factors
1. After come back to weighing mode do calibration.
2. Check balance readings in all measuring points.
3. In case of differences make a note.
4. If there is a positive difference you should add this difference to the factor.
If there is a negative difference you should subtract this difference to the factor.
Æ changing in the factory menu (service menu), parameters P0 37 until P0 67
E.g.:
weight mass 40g Æ reading 40.007
stored linearity factor at 40g Æ 0.001
input new linearity factor at 40g Æ 0.008
weight mass 40g Æ reading 39.995
stored linearity factor at 40g Æ 0.001
input new linearity factor at 40g Æ - 0.004
5. After inscribing correction you should do calibration again.
6. Check balance readings in all measuring points.
7. Repeat this process until you will get the expected results.
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8. Off-Center Load Adjustment
Scews to adjust the
of
f
-center load
Zero the display with nothing on the pan. Place a mass of ⅓ of maximum load at the
centre, than at the left, rear, right and front side of the pan, ½ of the way out from the
centre. The readings should agree within ± 5mg.
Using the attached figure. It is necessary to change the screws to make the readings
of the weight equal as it is moved around the pan.
Recheck corner load after 1 hour again.
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9. Printout of Factory Parameters
Open the housing and set jumper „JP1“ on main board 172xxx.PCB to access the
service menu.
Connect a standard printer to RS 232 data interface of the moisture analyzer.
Press the ON/OFF key (main switch) to turn on the balance.
Enter main menu
Set index next to parameter
P7 Globals
P1 alibration
P2 GLP
P3 D
P5 RS-232
P6
P7
C
ate/Time
P4 Redout
Printouts
Globals
Setup29.12.04
Enter menu P7 Globals
Enter submenu P7 09 Par. printout
To get a printout of the factory
parameters P0 01 to P0 75 set
Start= 0.01
Stop= 0.75
Confirm your setup with PRINT
Press PRINT to start the printout
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