KERN MBC M User manual

KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [e-mail]
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
Service Manual
Baby scale
KERN MBC_M
Version 1.0
05/2013
GB
MBC-M-SH-e-1310

2 MBC-M-SH-e-1310
GB
KERN MBC-M
Version 1.0 05/2013
Servicemanual
Contents
1Basic Information........................................................................................... 3
2Introdution...................................................................................................... 3
3MAINTENANCE .............................................................................................. 4
3.1 General....................................................................................................................................... 4
3.2 Error Codes ................................................................................................................................ 4
3.3 Determine the Problem............................................................................................................... 4
3.4 Check the Load cell.................................................................................................................... 4
3.5 Load Cell Connections ............................................................................................................... 5
3.6 Checking the different Voltages ................................................................................................. 5
3.7 Trouble Shooting ........................................................................................................................ 6
4DRAWING ....................................................................................................... 7
4.1 MBC HM..................................................................................................................................... 7
4.2 MBC oHM................................................................................................................................... 8

MBC-M-SH-e-1310 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 MCC 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-M-SH-e-1310
3 MAINTENANCE
3.1 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
3.2 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
3.3 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
3.4 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

MBC-M-SH-e-1310 5
3.5 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
3.6 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

6 MBC-M-SH-e-1310
3.7 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

MBC-M-SH-e-1310 7
4 DRAWING
4.1 MBC HM

8 MBC-M-SH-e-1310
4.2 MBC oHM

MBC-M-SH-e-1310 9
MBC
No. in Drawing
No. in Drawing
KERN Art.Nr.
HM
oHM
Key panel (15kg)
27
19
RMBC-4001
Key panel (20kg)
27
19
RMBC-4002
Battery cover
37
29
RMCC-8001
MBC-A04
MBC-A04
Footstand 1/2
48, 49
41, 42
RMBC-8001
Level bubble
26
18
RMPE-8003
Adapter socket
40
34
RMCC-5001
Plastic scale pan
1
1
RMBC-6001
Battery
50
43
MBC-A03
Pipe plug
20
RMBC-9001
Star (+) screw M4x30, Nut M4
46
16
RMBC-9002