KERN DE, DE6K2, DE15K5, DE30K10, DE60K20 Service Manual

KERN & Sohn GmbH

D-72322 Balingen-Frommern
Postbox 4052
E-Mail: [e-mail]

Tel: 0049-[0]7433- 9933-0
Fax: 0049-[0]7433-9933-149
Internet: www.kern-sohn.de

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Service Manual

Electronic Precision Balances

Page 2

KERN DE

version 1.1 06/01

DE-SH-e-0111

E

KERN DE

version 1.1 06/01

Service Manual
Electronic Precision Balances

1 INTRODUCTION .....................................................................................................3

1.1 Features............................................................................................................3

1.2 Digital auto adjusting procedure....................................................................3

1.3 Internal adjusting 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

4.1 Replacement of analogue PCBA ....................................................................8

4.2 Replacement of display PCBA .......................................................................8

5 SCHEMATICS.........................................................................................................9

6 SPARE PARTS LIST ............................................................................................13

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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 Adjusting

• Solder Pads to prevent end-user internal adjusting

• Low battery indicator

• Auto off function (battery mode only)

• AC adaptable

• Display segment test function

• Overload indication / protection

1.2 Digital auto adjusting procedure

1. Turn balance on and allow the unit to acclimatise and stabilise for two minutes.

2. Press and hold the MODE key until the display shows a flashing weight reading.
The flashing weight reading indicates the correct weight that must be placed on the
platform.

3. With the display still flashing, press the OFF key. The display will now show CAL 0.
Then gently place the correct adjusting weight on the centre of the platform.

4. The display will now show CAL F and then return to normal operating mode. The
adjusting is complete when the display correctly shows the weight that is placed on
the platform and the display has stabilised.

5. Remove the adjusting weight and press the TARE key to reset the zero point..

In case CAL E is display instead of CAL F, this indicates an adjusting procedure error.
Turn the balance off and then on and repeat the procedure.

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1.3 Internal adjusting procedure

1. Remove the bottom housing of the remote display box.

2. Connect J2 on the display board (by soldering).

3. With platform empty, turn the balance on. The display should now zero with the unit
indicator on.

4. Press the MODE key once. The display should show the internal count. The
reading should fall in the range from 9.500 to 10.000. In case out of this range,
adjust VR 1 located on the balance board inside the platform. Connecting pads on
J1 located underneath R4 on the solder side of the balance board can further
increase or reduce the reading.

5. Press the OFF key once. The display will show CAL 0 and then the required
adjusting weight. Place the corresponding adjusting weight in the centre of the
platform.

6. The display will now show CAL L and then the next adjusting weight. Place the
corresponding adjusting weight on the platform. Repeat this step until the display
shows CAL F.

7. Disconnect J2 on the display board. The adjusting is completed. Reset the zero
point and check the accuracy at different weights.

8. Install the bottom housing of the remote display box.

In case CAL E is displayed instead of CAL F, this indicates an adjusting procedure
error, or a wrong weight has been applied for adjusting. Turn the balance off and then
on and repeat the procedure.

1.4 Display segment test

Whenever the balance is turned on, all segments of the LCD will appear for 2 seconds.
Check for any missing segment.

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