Servicemanual for electronic precision
balances series
KERN EW/EG
Version 1.1 07/98
EW/EG-SU-e-9811
EW/EG-SU-e-9811
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CONTENTS
1 SECTION 1. TOTAL VIEW OF EW/WG...........................................................................................3
2 SECTION 2. ELECTRONIC CONSTRUCTION ...................................................................................4
2.1 Block diagramm KERN EW type..............................................................................................4
2.2 Block diagramm KERN EG type ...............................................................................................5
2.3 Whole wiring KERN EW type ...................................................................................................6
2.4 Whole wiring KERN EG type ...................................................................................................7
3 SECTION 3. TROUBLESHOUTING PROCEDURE .............................................................................8
3.1 Troubleshooting procedure .....................................................................................................8
3.2 Troubleshooting table .............................................................................................................9
3.3 Primary checks..................................................................................................................... 10
3.4 How to remove the case ....................................................................................................... 11
3.5 ON/OFF of lock switch ...........................................................................................................12
3.6 How to cover the case........................................................................................................... 12
4 SECTION 4. ADJUSTMENTS AND SETTINGS............................................................................... 13
4.1 Span calibration (Cal) - EW type ........................................................................................... 13
4.2 Corner error adjustment........................................................................................................ 14
4.3 How to adjust overload stopper............................................................................................ 15
4.4 Calibration of Built - In Weight (Ref Cal) - EG type.............................................................. 17
5 SECTION 5. PARTS REPLACEMENT............................................................................................ 19
5.1 Sequence of mechanism unit replacement .......................................................................... 19
6 Parts list for EW type ...................................................................................................................23
EW/EG-KB-e-9811
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1 SECTION 1. TOTAL VIEW OF EW/WG
Total view of round pan type - 150g --> 600g -
Total view of square pan type - 1500g --> 6kg -
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2 SECTION 2. ELECTRONIC CONSTRUCTION
2.1 Block diagramm KERN EW type
EW/EG-KB-e-9811
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2.2 Block diagramm KERN EG type
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2.3 Whole wiring KERN EW type
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2.4 Whole wiring KERN EG type
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3 SECTION 3. TROUBLESHOUTING PROCEDURE
3.1 Troubleshooting procedure
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3.2 Troubleshooting table
Symptoms Causes & Remedy
No display lights on 1. EW/EG board is defective.
2. AC adapter is defective.
3. Wrong connection of connection cords inside.
4. Built-in battery (option) is discharged.
u-Err or o-Err
appears after self
test of segments
(888...)
1. Wrong weighing pan is applied.
2. Tuning-fork sensor or mechanism unit is defective.
3. EW/EG board is defective.
4. Setting of address data has mistake.
5. Coefficient memories (address data) have changed
by noises or static electricity.
Adjust linearity.
Display does not
get settled down
Display does not
repeat correctly
Zero point drifts
1. Some parts such as stopper touches others.
2. Weighing pan touches other parts.
3. Foreign substance is in the scale.
4. Tuning-fork sensor or mechanism unit is defective.
5. Affected by a wind or disturbing oscillation.
Check environment or working base.
Check also setting of stabilization time.
See page 9 of operation manual.
o-Err appears
with a net load
less than specified
capacity (FS + 9d)
1. Big weight applied to the scale pan (net weight
+ tare value) exceeds the scale capacity.
2. Coefficient memories (address data) have changed
by noises or static electricity.
Adjust linearity.
3. Setting of address data has mistake.
4. Calibration weight is not correct.
Span is out of
specified range
1. Tuning-fork sensor or mechanism unit is defective.
2. EW/EG board is defective.
3. Setting of address data has mistake.
4. Coefficient memories (address data) have changed
by noises or static electricity.
Linearity is out of
specified range
1. Tuning-fork sensor or mechanism unit is defective.
2. Setting of address data has mistake.
3. Coefficient memories (address data) have changed
by noises or static electricity.
Adjust linearity.
4. Calibration weight is not correct.
Corner error is too
much
1. Mechanism unit is defective, such as Roberval
plate (spring) has been bent or twisted.
2. Pan base touches other parts.
Display suddently
disappeared in
operation
1. Built-in battery (option) has been consumed.
2. EW/EG board is defective.
3. AC adaptor is defective.
b-Err appears 1. EW/EG board is defective.
2. Coefficient memories (address data) have changed
by noises or static electricity.
Adjust linearity.
d-Err appears 1. Adress data related to determine the capacity
has been destroyed -----Contact the shipper.
2. EW/EG board is defective.
1-Err 1. The calibration weight is less than ½ F.S.
2-Err 1. The data error exceeds 0.4%.
Or perhaps the scale may be defective.
Contact the shipper.
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3.3 Primary checks
1. Is any wind around the site?
Is any oscillation?
Is the working table stable?
2. Is anything under the pan base or the weighing pan?
3. Is the weighing pan a right one?
4. Is AC adapter connected both with the scale and with the outlet properly?
5. Is battery option charged sufficiently?
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3.4 How to remove the case
1. Unplug the AC adapter.
Remove the pan and pan base.
2. Remove (2) case fixing screws with a philip driver.
3. Locate two hooks beneath the scale near to front.
Pull those two hooks toward you to lift the case up, then shift the case to rear
to release it from rear hooks.
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4. Remove the upper case and place it to the left.
Remove protector beforehand, if any.
3.5 ON/OFF of lock switch
Set the lock switch to "ON" before stamping or sealing so that
the user is unable to change parameters or to calibrate the scale.
3.6 How to cover the case
1. Cover the scale with the upper case, seeing cables are just stored
inside properly.
Insert the rear hooks first, then press the upper case gently
until two front hooks are set securely.
2. Drive in two case fixing screws securely.
3. Set pan base and then weighing pan on the scale.
4. Verify the setting of the Lock Switch.
When the setting of the Lock Switch is "OFF", display shows "8.8.8....."
followed by "ADJ." by energizing.
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4 SECTION 4. ADJUSTMENTS AND SETTINGS
4.1 Span calibration (Cal) - EW type
1. It is recommended to use a calibration weight of
better accuracy than the scale.
2. The calibration is available with ½ of F.S.
Nevertheless, it is recommended to use weight closer
to F.S. for accurate calibration.
3. Error messages:
0 - E r r : The calibration weight is over the full capacity.
1 - E r r : The calibration weight is less than ½ of the capacity.
2 - E r r : The data error exceeds 0.4%.
Or perhaps the scale may be defective.
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4.2 Corner error adjustment
Remove the upper case referring to page 9.
Place the pan base, then place the weighing pan on the mechanism.
Adjust the level.
Remove two fixing screws on EW/EG board and place the screws on the
plastic part of the lower case.
Adjust corner errors by adjusting bolts reffering to following illustrations.
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4.3 How to adjust overload stopper
1. Apply the pan base on the mechanism.
Then slide out stoppers by loosening two fixing screws with a hexagon wrench of 3 x 3.
2. Press the ON/OFF key to on while pressing F key and T key together
Release both keys when DJr____ appears.
3. Apply reference weights up to the Stopper Setting Value specified in the
table in page 15*1.
Press the T key to clear the display to zero (0).
4. Insert stoppers until they slightly touch corresponding guide link.
Holding the stopper with a screw driver
or the like, fix the stopper by driving
the cap screw securely.
5. The adjustment is good if display shows
between -5g and -50g.
Even the display shows "0", if the guide
link touches (stopped by) stoppers by increasing reference weights up to
Maximum specified in the table 15*2, the adjustments is good.
HOW TO KNOW WHEN LINK TOUCHES STOPPER
While increasing weights, when the guide link touches the stopper, the
display will not show as much value as increased weight.
This indicates the guide link has touched the stopper.
6. How to correct the setting
If the display value in above 5. Is less than -50g, such as -100g for
example, slide out stoppers a little from the guide link.
If the display value in above 5. Is over -5g, such as +5g for example,
insert the stoppers slightly more into the guide link.
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Table for stopper positioning
Models Weight applied
for setting *1
Weight to be
increased
Maximum weight
to be applied *2
EW - 300 - 2M
EG - 300 - 3M
600g 100g 700g
EW - 600 - 2M
EG - 600 - 2M
1000g 100g 1100g
EW - 6000 - 1M 8000g 500g 8500g
Caution
Erroneous setting of stoppers may cause destroying the tuning-fork sensor,
which is very delicate.
Guide link should be stopped with the Maximum Weight *2 without fail.
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4.4 Calibration of Built - In Weight (Ref Cal) - EG type
* Following does not describe the procedure of ordinary span calibration.
* This is the procedure of Calibration of the built- in weight
with EG scales.
* It is necessary to adjust the linearity of the scale beforehand.
Refer to page 19.
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Cautions are on next page --------->
-------------> continued from page 21
Cautions: 1. r E F. Cal must be carried out in following cases:
(1) When built-in weight is added or replaced.
(2) When linearity adjustments is done.
(3) When DJD board is replaced.
2. The quality/tolerance of the reference weight determine
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the accuracy of the scale.
Use weights of higher accuracy than the scale.
3. Adjust the level beforehand.
The ref-calibration must be done in a good environment, no wind, no oscillation
and no temperature changes.
4. I - E r r : The reference weight is less than ½ of F.S.
2 - E r r : The data error exceeds 0.4%.
Adjust the linearity.
5 SECTION 5. PARTS REPLACEMENT
5.1 Sequence of mechanism unit replacement
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1. How to remove weighing mechanism
(1) Remove the upper case referring to page 9.
(2) Remove three mechanism fixing nuts by a nut driver of opp. 7mm.
(3) Remove wires to the tuning-fork sensor, by welding solders at DJD circuit board.
(4) Remove the mechanism unit by holding at the lower case
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2. How to install weighing mechanism
(1) Place the mechanism on the lower case.
Fix it with three fixing nuts.
(2) Solder wires of the tuning-fork sensor to the DJD circuit board.
3. Cover the scale referring to page 10
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(1) Remove DJD board
(1) Remove the upper case referring to page 9.
(2) Unplug connectors at CN6 and CN4 on DJD board.
With battery option, unplug CN3 with output option, unplug CN1 and CN2 in addition.
(3) Unsolder T1, T2 and T3.
(4) Remove DJD board by removing two DJD fixing screw.
2. Installation of new PCB
(1) Install a new DJD board with two fixing screws.
(2) Plug connectors.
CN1 Output cord
CN3 Battery cord
CN6 DJ power cord (DC 9V in)
T1, T2, T3 Tuning-fork cord
(3) Cover the scale refering to page 10.
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6 Parts list for EW type
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Parts list for EW type
Part No. Part Name Material
1 140 ∅ round pan Stainless steel
2 140 ∅ round pan base assembly Aluminum
3 140 ∅ protector Stainless steel
4 Square pan Stainless steel
5 Square pan base assembly Iron
6-1 EW panel Polyester film
6-2 ----------------------------------------------- ------------------------------------------7 Top cover ABS
8 Side cover ABS
9-2 EW 300 - 2M Mechanism assembly Aluminum
9-3 EW 600 - 2M Mechanism assembly Aluminum
9-6 EW 6000 - 1M Aluminum
10 DJD circuit board assembly (Display PCB)
11 Mechanism unit base Iron
12 DJLF circuit board assembly (Power PCB)
13 Rear cover ABS
14 Under cover ABS
15 DJ level assembly ABS + glass
16-1 Adjuster Plastic
16-2 Adjuster Rubber
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Parts list for EG type
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Parts list for EG type
Part No. Part Name Material
1 110 ∅ round pan Stainless steel
2 110 ∅ round pan base assembly Aluminum
3 110 ∅ protector Stainless steel
4 140 ∅ round pan Stainless steel
5 140 ∅ round pan base assembly Aluminum
6 140 ∅ protector Stainless steel
7-1 EG panel Polyester film
7-2 ------------------------------------------------ ------------------------------------------8 Top cover ABS
9-1 EG 300 - 3M Mechanism assembly Aluminum
9-2 EG 600 - 2M Mechanism assembly Aluminum
10 DJD circuit board assembly (Display PCB)
11 Mechanism unit base Iron
12 Span holder Brass
13 Span weight Stainless steel
14 DJLF circuit board assembly (Power PCB)
15 Rear cover ABS
16 Under cover ABS
17 DJ level assembly ABS + glass
18 Adjuster Rubber
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