KERN MWA NM Series 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
Multi-function weighing balance
KERN MWA_NM
Type MWA300K-1NM
Type MWA300K-1PNM
07/2018
GB
MWA_NM-SH-e-1810

2 MWA_NM-SH-e-1810
GB
KERN MWA_NM
Version 1.0 07/2018
Servicemanual
Contents
1Basic Information........................................................................................... 3
2Appliance overview ....................................................................................... 4
3Keyboard overview........................................................................................ 7
4Overview of display....................................................................................... 8
4.1 Balance assembly and installation ............................................................................................. 9
4.2 Mains connection........................................................................................................................ 9
4.3 Battery operation is possible by obtaining an optional battery power pack. .............................. 9
4.4 Battery operation...................................................................................................................... 10
4.5 Insert batteries.......................................................................................................................... 10
5Menu ............................................................................................................. 11
5.1 Navigation in the menu............................................................................................................. 11
5.2 Menu overview ......................................................................................................................... 12
6Data output RS 232...................................................................................... 14
6.1 Pin allocation of balance output bushing:................................................................................. 14
6.2 Technical data .......................................................................................................................... 14
7Verification ................................................................................................... 15
7.1 Verification validity period (current status in G)........................................................................ 15
8Adjustment................................................................................................... 16
8.1 Procedure:................................................................................................................................ 17
9MAINTENANCE ............................................................................................ 18
9.1 General..................................................................................................................................... 18
9.2 Error Codes .............................................................................................................................. 18
9.3 Determine the Problem............................................................................................................. 19
9.4 Check the Load cell.................................................................................................................. 19
9.5 Checking the different Voltages ............................................................................................... 19
9.6 Trouble Shooting ...................................................................................................................... 21
10 Parts Replacement....................................................................................... 22
10.1 Replace load cell ...................................................................................................................... 22
10.2 Replace the mainboard ............................................................................................................ 23
11 DRAWING ..................................................................................................... 24

MWA_NM-SH-e-1810 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
This service manual covers the MWA_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.
For operation, please use the operating instructions corresponding to the device

4 MWA_NM-SH-e-1810
2 Appliance overview
The wheelchair platform scale MWA-NM with
folded and unfolded ramps and the display (serial
fitting).
The wheelchair platform scale
MWA-PNM with folded and
unfolded ramps, the display and
the rail with a stand (serial
fitting).
The possibility of retrofitting with
2nd rail MWA-A02 (without a
stand).
Folded wheelchair platform
scale MWA-PNM.

MWA_NM-SH-e-1810 5
Weighing balance suitable as
wheelchair or stand assist
balance.
1. Display Unit
2. Handrail optional
MWA-A01with tripod
(cannot be retrofitted)
MWA-A02 without tripod
3. Ramps
4. Bubble level
5. Carrying handle
Wheelchair balance
(Collapsible ramps)
Suitable as wheelchair and
stand assist balance
Handrail collapsible
Assembly of the rail:
Carefully mount the rail and fasten it
with screws.
The activity should preferably be
performed by two people.

6 MWA_NM-SH-e-1810
Display unit back
6. Adjustment switch
7. Terminal power supply unit
8. Connecting cable
”display unit - platform"
9. Connector RS232
Display unit at rear
5 Rechargeable battery /
battery compartment
6Mains port
7 RS 232 C
8 Adjustment switch

MWA_NM-SH-e-1810 7
3 Keyboard overview
Type MWA 300K-1NM
Type MWA 300K-1PNM
Button
Designation
Function
ON/OFF button
Turn on/off
Hold-key
Print-key
Hold function /determination of stable weighing value
Print (press and hold for a while):Data transmission via
interface RS 232
BMI key
Determination of body mass index
In the menu:
Confirm selection
For numeric entry:
Confirm numerical value
Function key
In menu:
Call up menu
Select menu items
For numeric entry:
Increase numerical value
Zeroing key
Weighing scale will be reset to „0.0“
For numeric entry:
Change decimal place
TARE key
Tare balance

8 MWA_NM-SH-e-1810
4 Overview of display
Display
Designation
Description
Stability display
Scales are in a steady state
Zeroing display
Should the balance not display exactly
zero despite empty weighing plate, press
the button.Your balance will be set
to zero after a short standby time.
NET
Net weight display
Illuminated when net weight is displayed
Illuminated after weighing scale was
tared
GROSS
Gross weight display
Illuminated when gross weight is
displayed
HOLD
HOLD function
HOLD function active
BMI
BMI function
Illuminated while BMI function is enabled
Rechargeable /Battery
display
Shows the capacity of the rechargeable /
batteries

MWA_NM-SH-e-1810 9
4.1 Balance assembly and installation
Level balance with foot screws until the air bubble of the
water balance is in the prescribed circle.
Check levelling regularly.
4.2 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.
Always use genuine approved KERN power pack units as per EN 60601-1 directive.
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 informs you during loading about the loading status of the
rechargeable battery.
green:
Rechargeable battery is completely discharged
blue:
Charging rechargeable battery
4.3 Battery operation 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. Charge the battery for at least 12 hours before initial use.
The appearance of the symbol in the weight display indicates that the battery
is almost exhausted. The weighing scale will remain ready for operation for a few
more minutes before switching off in order to save battery (s. operating instructions
corresponding to the device chap. 11.6 Auto off).Load rechargeable battery.
Voltage has dropped below prescribed minimum.
1

10 MWA_NM-SH-e-1810
Rechargeable battery very low.
Rechargeable battery completely reloaded
If the balance is not used for a longer time, take out the rechargeable battery and
store it separately. Leaking liquid could damage the balance.
4.4 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.
Capacity of batteries exhausted.
Batteries will soon be flat.
Batteries are completely charged
4.5 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.