E
Service Manual
Electronic Precision Balances
Page 2
KERN CH
version 1.0
CH-SH-e-0110
E
KERN CH
version 1.0
Service Manual
Electronic Precision Balances
1 INTRODUCTION .....................................................................................................3
1.1 Features............................................................................................................3
1.2 Simple span adjusting.....................................................................................3
1.3 Internal adjusting procedure ..........................................................................3
2 FUNCTIONAL BLOCK DIAGRAM / DESCRIPTION ..............................................4
2.1 Functional block diagram ...............................................................................4
2.2 Function description .......................................................................................5
3 TROUBLESHOOTING ............................................................................................6
4 REPLACEMENT OF PCBA ....................................................................................7
5 REPLACEMENT OF LOAD CELL ASSEMBLY .....................................................8
6 SCHEMATICS.........................................................................................................9
2 CH-SH-e-0110
1 Introduction
1.1 Features
• Tare function with indicator
• Display hold function
• Negative value indication
• Low battery indication
• Auto zero
• Auto off function
• Overload protection
• Internal adjusting by Variable Resistor
• Operated by 9 V alkaline battery
1.2 Simple span adjusting
1. Remove the label on the rear of the balance.
2. Turn the balance on by pressing the ON/TARE key.
3. Hang the weight onto the balance. Adjust the Variable Resistor (VR2) until the
balance reading matches with the weight.
4. Unload, reset to zero and repeat step 3 until there is no need to adjust VR2 to get
accurate readings.
1.3 Internal adjusting procedure
1. Remove the four screws and the rear housing of the balance.
2. Connect J4 on the analogue board.
3. With the balance on its weighing position, turn the balance on. The display will
show the internal counts. Adjust VR1 to set the reading within the range of 420 –
480.
4. Turn the balance off and disconnect J4. Turn the balance on again.
5. Hang a weight onto the balance. Adjust the Variable Resistor (VR2) until the
balance readings matches with the weight.
6. Unload, reset to zero and repeat step 5 until there is no need to adjust VR2 to get
accurate readings.
7. Install the rear housing of the balance with the four screws.
CH-SH-e-0110 3
2 Functional block diagram / description
2.1 Functional block diagram
9 V B a tte ry
Lo a d c e ll
(S e n so r)
Keybo ard
Po w er control /
Re g ulator &
Lo w b a tte ry
detector
Am plifier
LC D
Micro-
processor
Digita l signal
A/D C onverte r
Analogue signal
4 CH-SH-e-0110
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