KERN PNJ User manual

KERN & Sohn GmbH
Ziegelei 1
D-72336 Balingen
E-Mail: [email protected]
Tel: +49-[0]7433- 9933-0
Fax: +49-[0]7433-9933-149
Internet: www.kern-sohn.com
Servicemanual
Precision balances
KERN PNJ/PNS
Version 1.1
03/2020
GB

PNJ_PNS-SH-e-2011 - 2 -
GB
KERN PNJ/PNS
Version 1.1 03/2020
Servicemanual
Content
1Basic Information...........................................................................................- 3 -
2Introdution......................................................................................................- 3 -
3Keyboard overview ........................................................................................- 4 -
3.1 Overview of display...............................................................................................................- 5 -
3.2 Removing the case................................................................................................................- 6 -
3.3 Attaching the case.................................................................................................................- 7 -
4Trouble shooting table ..................................................................................- 8 -
4.1 Initial inspection ....................................................................................................................- 9 -
5Troubleschooting procedure ......................................................................- 10 -
6Inspection of electrical section (AJDP circuit board)................................- 11 -
7Adjustment ...................................................................................................- 12 -
7.1 Adjustment with internal weight (only models PNJ)........................................................- 12 -
7.2 Adjustment with external weight (only models PNS) ......................................................- 13 -
7.3 CALIBRATION OF BUILT-IN WEIGHT (REFCAL)..............................................................- 15 -
7.4 Resetting address data and linearity calibration..............................................................- 17 -
7.5 Resetting address data (coefficients)................................................................................- 18 -
7.5.1 Location for where to attach..................................................................................... - 18 -
7.5.2 How to read the data sheet....................................................................................... - 18 -
7.6 Linearity calibration ............................................................................................................- 19 -
7.7 Corner Error Adjustment ....................................................................................................- 20 -
7.8 Overload adjustment...........................................................................................................- 22 -
8Replacing the AJDP circuit board ..............................................................- 23 -
8.1 How to remove the AJDP circuit board.............................................................................- 23 -
8.2 Install the AJDP circuit board ............................................................................................- 25 -
9Removing the mechanism unit...................................................................- 27 -

- 3 - PNJ_PNS-SH-e-2011
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.
Detailed 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.
2 Introdution
This service manual covers the PNJ/PNS 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.
I

PNJ_PNS-SH-e-2011 - 4 -
3 Keyboard overview
Button
Function
Turn on/off
Transfer weighing data via interface
Exit menu / back to weighing mode.
Save settings/back to weighing mode
Switch-over weighing unit
Menu access (longer pressing of the button)
Scroll forward in menu
Taring
Zeroing
Change menu settings

- 5 - PNJ_PNS-SH-e-2011
3.1 Overview of display
Display
Description
g
Weighing unit “gram”
Zero indicator
NET
Display net weight values
Display of stable values
The balance is in stand-by mode
Illuminated during data transfer
Pcs
Application icon for piece counting
%
Application icon for percentage determination

Tolerance mark during check weighing
(mom)
Weighing unit „Momme“
M
The balance processor is just processing a function.
CAL
Illuminates and flashes during an adjustment process
Brackets for identifying non verified digits
(only verified models)
Capacity display
The bar graph display moves from the left to the right and
proceeds equally to the weight loaded onto the weighing
balance. Its full width is reached at maximum load. This is an
analogue display of the current allocation of the weighing area.
Units field
[ ] (ct) Carat
[ ] (oz) Ounze
[ ] (lb) Pound
[ ] (ozt) Feinunze
[ ] (dwt) Penny weight
[ ] (tl ) Tael (Hong Kong)
[
upper right] (tl
upper right) Tael (Singapore,Malaysia)
[
[ lower right ] (tl
lower right) Tael (Taiwan)
[ ] (to) Tola

PNJ_PNS-SH-e-2011 - 6 -
3.2 Removing the case
Remove the weighing pan and the pan base.
Circle p
a n (for ca pacity of 620 g or less) Square pan (for ca pacity of 1200 gr a ms or more)
Remove the hexagon head bolts attached in two locations and then remove
the protector and dust cover.
Circle p a n (for ca pacity of 620 gr a ms or less) Square pan (for ca pacity of 1200 gr a ms or more)
1. Dust cover
2. Protector
3. Hexagon bolts M3 x 8







- 7 - PNJ_PNS-SH-e-2011
Remove the tapping screws attached in two locations and then remove the case.
case Tabs (
i ns i d e )
Notches
Tapping Screw 4 mm x 10 mm long
3.3 Attaching the case
Attach the case by performing the reverse of the procedure in “3.2.1 Removing the case.”

PNJ_PNS-SH-e-2011 - 8 -
4 Trouble shooting table
Symptom
Cause and troubleshooting
Nothing appears
on display.
1. AJDP circuit board failure
2. AC adapter failure
3. Poor cable connection in scale
4. Uncharged battery
1. Replace the AJDP
circuit board.
2. Replace the AC
adapter.
3. Inspect inside of
scale.
4. Charge the battery.
“u-Err”or
“o-Err”appears
after “AA---”
appears.
1. Use of an irregular weighing pan
2. Tuning fork assy failure or
mechanical unit failure
3. AJDP circuit board failure
4. Incorrect setting of address data
(During data entry)
5. Coefficient memories (address
data) have changed by noises or
static electricity
1. Check the weighing
6. pan.
2. Replace the
mechanical unit.
3. Replace the AJDP
circuit board.
4. Check the address
data.
5. Check the address
data
Display value
is unstable.
Poor reproducibility
Zero point
fluctuates
1. Weighing pan (pan base) is
binding on something.
2. Foreign object inside scale
3. Tuning fork assy failure or
mechanical unit failure
4. Effect from wind or vibration (Is
the response speed too high?)
1. Check the weighing
pan.
2. Inspect the inside of
scale.
3. Replace the
mechanical unit.
4. Reconsider the
installation
location and
response speed.
“ ” appears
on display before
“Capacity + 9d”is
reached.
1. Sum of tare and weight exceeded
capacity
2. Coefficient memories (address
data) have changed by noises
or static electricity
3. Incorrect address data setting
(during data entry)
4. Span calibration utilized a weight
with a large error
1. Check the tare.
2. Check the address
data.
3. Check the address
data.
4. Check the weight.
Span has
large
deviation.
1. Tuning fork assy failure or
mechanical unit failure
2. AJDP circuit board failure
3. Incorrect address data setting
(during data entry)
4. Coefficient memories (address
data) have changed by noises
or static electricity
1. Replace the
mechanical unit.
2. Replace the AJDP
circuit board.
3. Check the address
data.
4. Check the address
data.
Poor linearity
1. Tuning fork assy failure or
mechanical unit failure
2. Incorrect address data setting
(during data entry)
3. Coefficient memories (address
data) have changed by noises
or static electricity
4. Span calibration used a weight
with a large error
1. Replace the
mechanical unit.
2. Check the address
data.
3. Check the address
data.
4. Check the weight.

- 9 - PNJ_PNS-SH-e-2011
Corner error
is too much
1. Mechanism failure
2. The weighing pan (pan base) is
binding on something.
1. Replace the
mechanical unit.
2. Check
installation of the
weighing pan
(pan base).
Display
disappears
during
measurement.
1. AJDP circuit board failure
2. AC adapter failure
1. Replace the AJDP
circuit board.
2. Replace the AC
adapter.
Display shows
“b-Err”
Display shows
“d-Err”
1. AJDP circuit board failure.
2. Coefficient memories (address data)
have changed by noises or static
electricity
1. Replace the AJDP
circuit board.
2. Check the
address data.
Display shows
“L-Err“
1. Sample weight is too light.
(Number of weights; in the %
(percentage weighing) mode)
1. Check the sample
weight.
Display shows
“I-Err”
1. Balance weight was lighter
than 50% of capacity during
span calibration.
1. Check the balance
weight.
Display shows
“2-Err”
1. Error exceeding 1%
occurring in span calibration
1. Check the error.
4.1 Initial inspection
1. Check that no wind or vibration affects the scale.
2. Check that the pan base and the weighing pan are properly installed.
3. Check that there are no foreign objects below the weighing pan (pan base).
4. Check that a regular weighing pan is used.
5. Check that the stand on which the scale is placed is stable.
6. Check that the scale is level.
7. Check that anAC adapter is connected.
8. Check that the battery is sufficiently charged (in the battery option).

PNJ_PNS-SH-e-2011 - 10 -
5 Troubleschooting procedure
START
„88" appears on
display
Perform initial inspection
YES
Display shows
Is display stable?
Weight
Is capacity display
stable?
YES
Corner error
inspection
YES
Linear error check
OK
Balance operates normal
OK
Check stopper typeNO Re-adjustFAULTY
Is AC Adaptor
connected?
Connect AC Adaptor.
NO
Connectors ar
inserte?
Check memory
content
0- er r / u- er r
Reset address data
Not good
Return to initial
inspection
Check output
waveforms
OK
Tunning fork assy failure
FAULTY
Replace tunning fork
assy
Mechanical unit failure
GOOD
Replace mechanical unit
Is supply voltage of
circut correct?
YES
APS-LF board is
normal
AJDP circut board failure
YES
APS-LF board failure
NO
Replace the AJDP circut
board Replace the APS-LF board
Linearity calibration
Not Good
Corner error adjustment
Not Good
NO
Display weight
Insert connection
NO
NO
OK