KERN MBC-(E) User manual

KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: info@kern-
sohn.com
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-
149
Internet: www.kern-
sohn.com
Service Manual
Baby scale
KERN MBC-(E)
Typ MBC 15K2DNM (DEM)
Typ MBC 20K10NM (EM)
Version 1.1
02/2020
GB
MBC-NM-SH-e-2011
Importør:
Impex Produkter AS
Gamle Drammensvei 107
1363 Høvik
www.impex.no
[email protected]
Tel.: [phone]

2 MBC-NM-SH-e-2011
GB
KERN MBC
Version 1.1 02/2020
Servicemanual
Contents
1Basic Information........................................................................................... 3
2Introdution...................................................................................................... 3
3Appliance overview ....................................................................................... 4
3.1 Overview of display .................................................................................................................... 5
3.2 Keyboard overview..................................................................................................................... 6
4Levelling ......................................................................................................... 7
4.1 Rechargeable battery operation (MBC-A08).............................................................................. 7
4.2 Battery operation........................................................................................................................ 8
4.3 Insert batteries............................................................................................................................ 8
4.4 Mains connection........................................................................................................................ 9
4.5 Initial Commissioning.................................................................................................................. 9
5Menu ............................................................................................................. 10
5.1 Navigation in the menu............................................................................................................. 10
5.2 Menu overview ......................................................................................................................... 11
6Position adjustment switch and seals:...................................................... 13
7Adjustment................................................................................................... 14
7.1 Procedure:................................................................................................................................ 15
8MAINTENANCE ............................................................................................ 17
8.1 General..................................................................................................................................... 17
8.2 Error Codes .............................................................................................................................. 17
8.3 Determine the Problem............................................................................................................. 17
8.4 Check the Load cell.................................................................................................................. 17
8.5 Load Cell Connections ............................................................................................................. 18
8.6 Checking the different Voltages ............................................................................................... 18
8.7 Trouble Shooting ...................................................................................................................... 19
9DRAWING ..................................................................................................... 20
9.1 MBC HM................................................................................................................................... 20
9.2 MBC oHM................................................................................................................................. 21

MBC-NM-SH-e-2011 3
1 Basic Information
The device must be repaired only by trained specialist staff or personnel with professional
formation (such as a repair-specialist accredited by law concerning verification). The service
manual is obligatory for repair work. After repair, original conditions of the device have to be
restored. Only original spare parts should be used.
Instructions about conformity-evaluated scales:
Repair must be carried only at 100% compliance with the type approval. A violation of this
specification will result in a loss of the type approval! After successful repair the balance will
have to be reverified before it can be used again in a statutorily regulated field.
The operation and configuration of each scale is described in the accompanying manual of
the scale. Any safety information in respect for verification are also described in the
accompanying manual
2 Introdution
This service manual covers the MBC-NM series and is edited for the authorized servicing
personnel.
Note all rights are reserved. Copying any part of this manual is prohibited without our
permission.

4 MBC-NM-SH-e-2011
3 Appliance overview
1. Height measuring rod (optional)
2. Bubble level
3. Display Unit
4. LED
5. Baby weighing pan
6. Weighing pan
7. Rubber feet (height adjustable)
8. Mains connection
9. Battery compartment
10. RS232

MBC-NM-SH-e-2011 5
3.1 Overview of display
Display
Description
Description
GROSS
Gross weight display
Lights up during indication of the gross
weight of the baby (after drinking)
NET
Net weight display
Lights up during indication of the net weight
of the baby (before drinking)
Illuminated after weighing scale was tared
ZERO
Zeroing display
Should the balance not display exactly zero
despite empty scale pan, press the
button. Your balance will be set to zero after
a short standby time.
STABLE
Stability display
Scales are in a steady state
DRINK
DRINK function
Is displayed with active drink function
HOLD
HOLD function
Is displayed with active hold function
Rechargeable battery
symbol
Lights when the voltage drops below the
prescribed minimum.
Lights when the rechargeable battery
capacity is almost exhausted.
Lights when the rechargeable battery is fully
charged.

6 MBC-NM-SH-e-2011
3.2 Keyboard overview
Typ MBC 15K2DNM
Typ MBC 20K10NM
Key
Description
Function
ON/OFF-switch
Turn on/off
Zeroing key
Weighing scale will be reset to „0.0“ kg.
For numeric entry:
Change decimal place
HOLD button
Hold function
TARE button
Tare balance
Feeding Function
key
Differential weighing before and after the baby drinks
The net weight of the baby will be shown:
Before drinking
In menu:
Call up menu
How to select menu items
For numeric entry:
Edit numeric value
The gross weight is displayed:
After drinking
In menu:
Confirm selection
For numeric entry:
Confirm numerical value

MBC-NM-SH-e-2011 7
4 Levelling
Level balance with foot screws until the air bubble of the water
balance is in the prescribed circle.
4.1 Rechargeable battery operation (MBC-A08)
(is possible by obtaining an optional battery power pack)
Open the battery compartment cover (1) at the base of the display unit and insert the
rechargeable battery pack. Charge the battery for at least 12 hours before initial use.
The appearance of the symbol in the weight display indicates that the battery packs
is almost exhausted. The weighing scale will remain ready for operation for a few more
minutes before switching off in order to save battery. Load rechargeable battery.
Voltage has dropped below prescribed minimum.
Rechargeable battery very low.
Rechargeable battery completely reloaded
If the balance is not used for a longer time, take out the battery pack and store it separately.
Leaking liquid could damage the balance.

8 MBC-NM-SH-e-2011
4.2 Battery operation
As an alternative to rechargeable battery operation, the balance may also be operated with
6x AA batteries.
Open battery compartment cover (1) at the lower side of the display unit and insert batteries
according to the example below. Lock the battery cover again. If the batteries are empty, in
the balance display appears the symbol . Change batteries. To save battery power,
the balance switches off automatically (see Instruction manual MBC chap.11.6 Auto off).
Capacity of batteries exhausted.
Batteries will soon be flat.
Batteries are completely charged
4.3 Insert batteries
Remove battery compartment cover
Connect battery holder to housing contact
acc. to illustration
Insert battery holder
Insert batteries into battery compartment
and lock with battery compartment cover.

MBC-NM-SH-e-2011 9
4.4 Mains connection
Power is supplied by the external power unit which also serves to isolate the mains supply
from the scale. The stated voltage value must be the same as the local voltage.
Only approved genuine KERN power supply units may be used in compliance with Directive
EN 60601-1.
The small sticker attached to the side of the display unit indicates the power port:
The LED remains illuminated as long as the weighing scale remains connected to the mains.
The LED display provides information about the battery's charging status.
Green: battery is fully charged
Blue: battery is charging
4.5 Initial Commissioning
In order to obtain exact results with the electronic balances, your balance must have reached
the operating temperature (see warming up time chap. During this warming up time the
balance must be connected to the power supply (mains, accumulator or battery) and be
switched on.
The accuracy of the balance depends on the local acceleration of gravity.
The value of gravity acceleration is shown on the type plate.

10 MBC-NM-SH-e-2011
5 Menu
Access to service menu „tCH“is locked in verified balances.
To disable the access lock, destroy the seal and actuate the
adjustment switch. For position of adjustment switch, see Instruction
manual MBC chap. 13.
Attention:
After destruction of the seal the weighing system must be re-verified
by an authorised agency and a new verification wire/seal mark fitted
before it can be reused for applications subject to verification.
5.1 Navigation in the menu
Call up menu
Turn on the scale during the self-test press , the first
function [F1 oFF] is displayed.
Select function
With help of , the individual functions can be selected one
after the other.
Change settings
Confirm selected function by . The current setting will be
displayed.
Select the desired setting with and press to confirm or
to reject, the balance returns to the menu.
Exit menu/
Return to weighing
mode
Press , the balance will return to weighing mode.

MBC-NM-SH-e-2011 11
5.2 Menu overview
Function
Settings
Description
F1 oFF
Automatic cutout
Auto Off
oFF 0*
Automatic shutdown off
oFF 3
Automatic shutdown after 3 min
oFF 5
Automatic shutdown after 5 min
oFF 15
Automatic shutdown after 15 min
oFF 30
Automatic shutdown after 30 min
F2 bk
Background
illumination
of display
bl on
Back lighting for display on
bl oFF
Display background illumination off
bl AU*
Backlighting for display will come on automatically
as soon as the weighing scale is operated.
tCH
Service menu
Pin
If display shows "Pin" adjust switch.
Then press , ., subsequently.
P1 Spd
Display speed
15*
Not documented
30
60
7.5

12 MBC-NM-SH-e-2011
P2 CAL
duA in
dESC
C 0.00
C 0.000
C 0.0000
C 0
C 0.0
inC
Sd iv 1
div 1, 2, 5, 10, 20, 50
Sd iv 2
div 1, 2, 5, 10, 20, 50
CAP
CAP 1
CAP 2
CAL
UnLoAd
StrAnG
St 100
St 200
St 500
duA rA
dESC
C 0.00
C 0.000
C 0.0000
C 0
C 0.0
inC
Sd iv 1
div 1, 2, 5, 10, 20, 50
Sd iv 2
div 1, 2, 5, 10, 20, 50
CAP
CAP 1
CAP 2
CAL
Justierung
UnLoAd
StrAnG
St 100
St 200
St 500
SnG rA
dESC
C 0.00
C 0.000
C 0.0000
C 0
C 0.0
inC
Sd iv 1
div 1, 2, 5, 10, 20, 50
Sd iv 2
div 1, 2, 5, 10, 20, 50
CAP
CAP 1
CAP 2
CAL
UnLoAd
StrAnG
St 100
St 200
St 500

MBC-NM-SH-e-2011 13
P3 Pro
tri
Not documented
CoUnt
Not documented
rESEt
Reset weighing scale to factory setting
SEtGrA
Not documented
* default setting
6 Position adjustment switch and seals:
1. Self-destroying seal mark
2. Cover
3. Adjustment switch
1
1
2
3

14 MBC-NM-SH-e-2011
7 Adjustment
As the acceleration value due to gravity is not the same at every location on earth, each
display unit with connected weighing plate must be coordinated - in compliance with the
underlying physical weighing principle - to the existing acceleration due to gravity at its place
of location (only if the weighing system has not already been adjusted to the location in the
factory). This adjustment process must be carried out for the first commissioning, after each
change of location as well as in case of fluctuating environment temperature. To receive
accurate measuring values it is also recommended to adjust the display unit periodically in
weighing operation.
Prepare the required adjustment weight. The adjustment weight to be applied
depends on the capacity of a weighing scale, see Instruction manual MBC
chap. 1.
Carry out adjustment as closely as possible to admissible maximum load of
weighing scale. Information about test weights you will find in the internet
under http://www.kern-sohn.com
Observe stable environmental conditions. For warm-up time required for
stabilisation see Instruction manual MBC chpt 1.
Access to service menu „tCH“is locked in verified balances.
To disable the access lock, destroy the seal and actuate the adjustment
switch. Position of the adjustment switch see nstruction manual MBC chap.
13.
Attention:
After destruction of the seal the weighing system must be re-verified by an
authorised agency and a new verification wire/seal mark fitted before it can
be reused for applications subject to verification.

MBC-NM-SH-e-2011 15
7.1 Procedure:

Turn on the scale during the self-test press , the first function
[F1 oFF] is displayed.
Press repeatedly until "t CH" is displayed.
Press , [Pin] is displayed
Operate adjustment switch; for position see chap.13
Press , and subsequently, [P1 SPd] will appear

Press , „P2 CAL“ will be displayed


Press , the currently set balance type is displayed.
SnGrA = single range balance
dUArG = dual range balance
To change select scale type with and confirm with ,
[dESC] appears.
Press repeatedly until „CAL“ will be displayed.
Confirm with , [UnloAd] appears

16 MBC-NM-SH-e-2011
Ensure that there are no objects on the weighing pan.
Wait for stability display "STABLE", then confirm with
(example)
The size of the currently set adjustment weight is displayed, the
active site flashes.
If required, select with he digit to be altered and change the
digit with .
Confirm with , [LoAd] appears

Put the required adjustment weight carefully in the centre of the
weighing pan.
Wait until stability display „STABLE“ appears
Confirm with [PASS] is displayed.
After the adjustment the balance will carry out a self-test. Remove
adjusting weight during selftest, balance will return into weighing mode
automatically.
An adjusting error or incorrect adjusting weight will be indicated by the
error message; repeat adjustment procedure.
An adjusting error or incorrect adjustment weight will generate an error
message („Err 4“), repeat the adjustment process.

MBC-NM-SH-e-2011 17
8 MAINTENANCE
8.1 General
Please clean the scale each week and do calibration every year.
If the scale does not operate properly, find out the problem as possible.
Determine whether the problem is constant or alternate. Be aware that problems can be
caused by mechanical or electrical influences.
Check the following.
Water
Corrosive materials
Vibrations or temperature or wind
Physical damage
Check the scale cables for damage, and check all connections and connecters for any loose
contact or incorrect connection
8.2 Error Codes
Error Code
Description
POSSIBLE CAUSES
Err 4
Zero range exceeded, due to
turning on or by pressing
Goods on the platform
Overload, when zeroing
the scale.
Improper calibration
Load cell problem
PCB problem
Err 6
A/D Count out of the range
Platform not installed
Load cell problem
PCB problem
8.3 Determine the Problem
Determine whether the problem is in the PCB or the Load Cell
Disconnect the power supply from the scale, and disconnect the load cell connection
from the PCB
Reapply power and test the PCB
If problem goes away, its source is probably in the Load cell. Check the wiring,
connecter, load cell and mechanical components of the load cell.
If problem persists, its source is probably in the PCB. Check the PCB voltages,
connecters, cables and function programs
8.4 Check the Load cell
Remove power from the system, and disconnect the PCB from the Load cell
Make sure all leads are connected and correctly.
Check load cell for proper input and output resistances

18 MBC-NM-SH-e-2011
8.5 Load Cell Connections
Signal + Green
Supply + Red
Signal - Black
Supply - White
Shield
Measuring Points
Resistance
Red (+ Exc) to White ( –Exc)
420 ±20Ω
Green (+Sig) to Black ( –Sig)
350Ω ±5Ω
8.6 Checking the different Voltages
If the problem is in the PCB, use a multimeter to check the following voltages
AC Power
Check the AC power socket out put voltage.
Adaptor Voltage
Check the adaptor output cable connecter voltage
Compare the value with the name plate on the scale
PCB Input Voltage
Check the PCB input power connecter voltage
Voltage must be minimum 9VDC in to the pin AD+
Check Battery Voltage and Charging Voltage
Check the Battery Voltage,
Voltage must be minimum 6VDC. If below the 6VDC connect the adaptor for charging
The battery voltage below the 5.5VDC, replace the battery and install new 6V/3.4Ah
battery.
Check the Battery Charging Voltage;
Remove the battery connection terminals (Red and Black) from the battery. Connect the
power and turn on the scale Voltage into the terminal minimum 6.5VDC

MBC-NM-SH-e-2011 19
8.7 Trouble Shooting
Problems
Possible cause
Common Solutions
Display is blank.
No self test
Mains power is turned
off. Power supply faulty
or not plugged. Internal
battery is not charged.
On/Off switch problem
Check power is getting inside the scale
and on/off switch is working.
Verify the voltages, which is on the
power labels.
Blank display after
self test
Pan not installed.
Unstable weight, load
cell damaged
Check the pans are installed correctly.
Try to turning on again.
OL or -------
Maximum capacity
exceeded. Load cell or
mechanics damaged.
Power supply faulty
Check the platform is installed
correctly. Try to turn on the scale
again. Do the calibration again
------- or NULL
displayed
Weight is on the platform
is below permissible limit.
Pan not installed
correctly.
Power supply faulty.
Load cell or mechanism
faulty
Check the platform is installed
correctly. Try to turn on the scale
again.
Do the calibration again
Display is unstable
Goods touching
somewhere. Air variation
or any vibrations.
Temperature changed .
Load cell or connections
faulty.
Power supply faulty
Check the scale is in acceptable
location.
Check the connecters and load cell.
Check the power supply and battery
Weight value
incorrect
Calibration error.
Platform of load cell
touching somewhere.
Wrong weighing unit
Use accurate weight for to do the
calibration
Check the pan and load cell is installed
proper and touching.
Check the parameter settings.
Check the load cell and connecters
Can not use full
capacity
Over load protection
stoppers or transport
locks are not removed.
Parameters are set
incorrectly.
AD problem.
Load cell or mechanism
damaged
Check the stoppers and locks under
the platform.
Check the weighing unit and parameter
settings.
Check the load cell.
Platform Corner
Weight different
Over load protection
stoppers or transport
locks are not removed.
Load cell or mechanism
damaged
Check the stoppers and locks under
the platform.
Use accurate weight for to do the
calibration
Check the load cell.
Battery not
charging
Mains voltage problem
Charging circuit problem
Battery Problem
Check the mains and adaptor.
Check the battery.
Check the charging circuit

20 MBC-NM-SH-e-2011
9 DRAWING
9.1 MBC HM