Kern 440-47, 440-45, 440-33 Service Manual
E
KERN & Sohn GmbH
D-72322 Balingen-Frommern
Postbox 4052
E-Mail: info@kern-sohn.de
Service Manual
Electronic Precision Balances
Tel: 0049-[0]7433- 9933-0
Fax: 0049-[0]7433-9933-149
Internet: www.kern-sohn.de
Page 2
KERN 440-33 /-45/-47
1 PCB
Version 2.0
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E
KERN 440-33 /-45 /-47
Version 2.0 / 1 PCB
Service Manual
Electronic Precision Balances
1 INTRODUCTION.....................................................................................................3
1.1 Features ...........................................................................................................3
1.2 Digital auto calibration procedure .................................................................3
1.3 Internal calibration procedure........................................................................4
1.4 Display segment test ......................................................................................4
2 FUNCTIONAL BLOCK DIAGRAM / DESCRIPTION.............................................. 5
2.1 Functional block diagram............................................................................... 5
2.2 Function description....................................................................................... 6
3 TROUBLESHOOTING............................................................................................ 7
4 REPLACEMENT OF PCBA .................................................................................... 8
5 REPLACEMENT OF LOADCELL ASSEMBLY......................................................9
6 SCHEMATICS.......................................................................................................10
7 COMPONENTS LAYOUT..................................................................................... 11
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1. Introduction
1.1 Features :
Full Tare
•
Memory function with indicator
•
Stable indicator
•
Negative value indication
•
Two types of Digital Auto Calibration
•
Solder pads to prevent end-user internal calibration
•
Low battery indicator
•
Auto off function (battery mode only)
•
AC adaptable
•
Display segment test function
•
Overload protection
•
1.2 Digital Auto Calibration Procedure :
Turn balance on and allow the unit to acclimatize and stabilize for two minutes.
1.
Press and hold the [CAL/MODE] key until the display shows a flashing weight
2.
reading. The flashing weight reading indicates the correct weight that must be
placed on the tray.
With the display still flashing, press the off key. The display will now show [CAL 0].
3.
Then gently place the correct calibration weight on the center on the tray.
The display will now show [Cal F] and then return to normal operating mode. The
4.
calibration is complete when the display correctly shows the weight that is placed on
the tray and the display has stabilized.
Remove the calibration weight and press the [TARE] key to reset the zero point.
5.
In case [CAL E] is displayed instead of [CAL F], this indicates a calibration
procedure error. Turn the scale off and then on and repeat the procedure
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1.3 Internal Calibration Procedure :
Remove the top housing of the scale.
1.
Connect J1 by soldering the pads together.
2.
With tray top installed, turn balance on. Display shall show zero with the unit
3.
indicator on.
Press [CAL/MODE] key once. Display shall show the internal count. The reading
4.
shall fall in the range from 9000 to 12000. In case out of this range, connect J10 left
side or right side to reduce or increase the reading. Connecting or disconnecting
pads on J7, J8, or J9 can fine tune the reading.
Press [OFF] key once. Display will show [CAL 0] and then the required calibration
5.
weight. Place the corresponding calibration weight on the center of the tray.
Display will now show [CAL L] and then the next calibration weight. Place the
6.
corresponding calibration weight on the tray. Repeat this step until display shows
[CAL F].
Disconnect J1. Reset the zero point and check the accuracy at different weight.
7.
Install the top housing of scale.
8.
(refer to drawing : component layout)
In case [CAL E] is display instead of [CAL F], this indicates a calibration procedure error,
or wrong weight applied for calibration. Turn the scale off and then on and repeat the
procedure.
1.4 Display Segment Test :
Whenever the scale is power on, all segments of the LCD will be turn on for 2 seconds.
Check for any missing segment.
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