KERN RFC 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
Service Manual
Price calculating balance
KERN RFC
Version 1.0
02/2018
GB
RFC-SH-e-1810

2 RFC-SH-e-1810
GB
KERN RFC
Price calculating balance
Version 1.0 03/2018
Service manual
Content
1Basic Information .........................................................................................4
2Introdution.....................................................................................................4
3Appliance overview......................................................................................5
3.1 Overview of display............................................................................................................6
3.2 Display weight.....................................................................................................................7
3.3 Display basic price .............................................................................................................7
3.4 Display sale price ...............................................................................................................7
3.5 Battery loading status display ..........................................................................................7
1.1 Keyboard overview.............................................................................................................8
4Basic Information (General).........................................................................9
4.1 Proper use...........................................................................................................................9
4.2 Improper Use.......................................................................................................................9
4.3 Warranty ..............................................................................................................................9
4.4 Monitoring of Test Resources...........................................................................................9
5Basic Safety Precautions...........................................................................10
5.1Pay attention to the instructions in the Operation Manual ..........................................10
5.2 Personnel training ............................................................................................................10
6Transport and storage................................................................................10
1.2 Testing upon acceptance ................................................................................................10
6.1 Packaging / return transport ...........................................................................................10
7Unpacking, Setup and Commissioning....................................................11
7.1 Installation Site, Location of Use....................................................................................11
7.2 Unpacking .........................................................................................................................11
8Placing.........................................................................................................12
8.1 Scope of delivery / serial accessories: ..........................................................................12
8.2 Mains connection .............................................................................................................12
8.3 Storage battery operation (optional) ..............................................................................12
9Adjustment..................................................................................................13
10 Verification...............................................................................................15
10.1 Adjustment switch and seals ..........................................................................................16
10.2 Checking the balance verification settings ...................................................................16
11 The menu .................................................................................................17
11.1 Access to menu ................................................................................................................17
11.2 Navigation in the menu:...................................................................................................17
11.3 Menu overview..................................................................................................................18
12 Instant help..............................................................................................20
13 Error messages.......................................................................................21

RFC-SH-e-1810 3
14 Drawing....................................................................................................23
14.1 without pole.......................................................................................................................23
14.2 with pole ............................................................................................................................24
15 Circuit diagram........................................................................................25
15.1 MCU....................................................................................................................................25
15.2 Power.................................................................................................................................26
15.3 Display board....................................................................................................................26
16 Trouble shooting.....................................................................................27
17 Maintanace...............................................................................................29
17.1 General ..............................................................................................................................29
17.2 Cleaning.............................................................................................................................29
17.3 Determine the Problem....................................................................................................29
17.4 Check the Load ce ll ..........................................................................................................29
17.5 Load Cell Connections.....................................................................................................30
17.6 Check PCB Voltages........................................................................................................30
17.7 AC Power...........................................................................................................................30
17.8 Adaptor Voltage................................................................................................................30
17.9 PCB Input Voltage............................................................................................................30
17.10 Check Battery Voltage and Charging Voltage ..........................................................31
17.11 Replace Main Board .....................................................................................................31
17.12 Replace Load Cell.........................................................................................................31
17.13 Replace Battery.............................................................................................................32

4 RFC-SH-e-1810
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 RFC 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.
In this lineup it is an eco product, Therefore, it is not intended to represent the repair
manual in detail, since the construction of the balance is very simple. It is therefore only
referring to the list of related to disposal spare parts.

RFC-SH-e-1810 5
3 Appliance overview
Models without vertical display:
Models with post-mounted display:
1. Weighing pan
2. Bubble level
3. Post-mounted display
4. Footscrews
5. Mains adapter connection
6. ON/OFF switch
7. RS 232 interface
8. Battery compartment
9. Adjustment switch

6 RFC-SH-e-1810
3.1 Overview of display
Operator and secondary display (standard on the backside of models without
post-mounted display):
Additional post-mounted display for models with tripod:

RFC-SH-e-1810 7
3.2 Display weight
Here, the weight of your goods is displayed.
Indicator next to symbol displays:
Rechargeable battery very low
NET
Net weight
Stability display
a
Zeroing display
3.3 Display basic price
Basic price, can be switched over from € / kg or € / 100 g.
Indicator next to symbol displays:
€/kg
Basic price in €/kg
€/100 g
Basic price in €/100 g
AUTO CLEAR
Set basic price is deleted automatically when balance
is unloaded
3.4 Display sale price
Here the sales price is displayed in Euro [€].
Indicator next to symbol displays:
BAR
Calculating the change (see chap. 10.3)
3.5 Battery loading status display
red
Charging storage battery
green
Rechargeable battery completely reloaded

8 RFC-SH-e-1810
3.6 Keyboard overview
Selection
Function
~
Numerical keys, PLU-keys
In menu: Invoke parameter
Delete
Save basic price (press key for a long time),
see chap. 10.2
Call-up basic price (press and hold key for a short time), see
chap. 10.2
Switch-over unit € / kg € / 100g
Issue to external device
In menu:Parameter selection
Calculating the change, see chap. 10.3
Taring, see chap. 9.3
In menu: Storing settings
For activated function, the set basic price is automatically
deleted when the balance is unloaded.
Enter basic price per piece (without weighing)
Zeroing
In menu: Back to weighing mode
Decimal point

RFC-SH-e-1810 9
4 Basic Information (General)
4.1 Proper use
The balance you purchased is intended to determine the weighing value of material to be
weighed. It is intended to be used as a “non-automatic balance”, i.e. the material to be
weighed is manually and carefully placed in the centre of the weighing pan. As soon as a
stable weighing value is reached the weighing value can be read.
4.2 Improper Use
Do not use balance for dynamic weighing. In the event that small quantities are removed
or added to the material to be weighed, incorrect weighing results can be displayed due
to the “stability compensation“! (Example: Slowly draining fluids from a container on the
balance.)
Do not leave permanent load on the weighing pan. This may damage the measuring
system.
Impacts and overloading exceeding the stated maximum load (max) of the balance,
minus a possibly existing tare load, must be strictly avoided. Balance may be damage by
this.
Never operate balance in explosive environment. The serial version is not explosion
protected.
The structure of the balance may not be modified. This may lead to incorrect weighing
results, safety-related faults and destruction of the balance.
The balance may only be used according to the described conditions. Other areas of use
must be released by KERN in writing.
4.3 Warranty
Warranty claims shall be voided in case
Our conditions in the operation manual are ignored
The appliance is used outside the described uses
The appliance is modified or opened
Mechanical damage or damage by media, liquids, natural wear and tear
The appliance is improperly set up or incorrectly electrically connected
The measuring system is overloaded
4.4 Monitoring of Test Resources
In the framework of quality assurance the measuring-related properties of the balance
and, if applicable, the testing weight, must be checked regularly. The responsible user
must define a suitable interval as well as type and scope of this test. Information is
available on KERN’s home page (www.kern-sohn.com with regard to the monitoring of
balance test substances and the test weights required for this. In KERN's accredited
DKD calibration laboratory test weights and balances may be calibrated (return to the
national standard) fast and at moderate cost.

10 RFC-SH-e-1810
5 Basic Safety Precautions
5.1 Pay attention to the instructions in the Operation Manual
Carefully read this operation manual before setup and commissioning, even if
you are already familiar with KERN balances.
5.2 Personnel training
The appliance may only be operated and maintained by trained personnel.
6 Transport and storage
1.1 Testing upon acceptance
When receiving the appliance, please check packaging immediately, and the appliance
itself when unpacking for possible visible damage.
6.1 Packaging / return transport
Keep all parts of the original packaging for a possibly required return.
Only use original packaging for returning.
Prior to dispatch disconnect all cables and remove loose/mobile parts.
Reattach possibly supplied transport securing devices.
Secure all parts such as the glass wind screen, the weighing platform,
power unit etc. against shifting and damage.

RFC-SH-e-1810
11
7 Unpacking, Setup and Commissioning
7.1 Installation Site, Location of Use
The balances are designed in a way that reliable weighing results are achieved in
common conditions of use.
You will work accurately and fast, if you select the right location for your balance.
On the installation site observe the following:
Place the balance on a firm, level surface;
Avoid extreme heat as well as temperature fluctuation caused by installing next
to a radiator or in the direct sunlight;
Protect the balance against direct draughts due to open windows and doors;
Avoid jarring during weighing;
Protect the balance against high humidity, vapours and dust;
Do not expose the device to extreme dampness for longer periods of time. Non-
permitted condensation (condensation of air humidity on the appliance) may
occur if a cold appliance is taken to a considerably warmer environment. In this
case, acclimatize the disconnected appliance for ca. 2 hours at room
temperature.
Avoid static charge of goods to be weighed or weighing container.
If electro-magnetic fields or static charge occur, or if the power supply is unstable major
deviations on the display (incorrect weighing results) are possible.In that case, the
location must be changed.
7.2 Unpacking
Carefully remove the balance from the packaging, remove plastic cover and
setup balance at the intended workstation.

12 RFC-SH-e-1810
8 Placing
Level balance with foot screws until the air bubble of the water
balance is in the prescribed circle.
8.1 Scope of delivery / serial accessories:
Balance, see chap. 3
Mains adapter
Protective cover
Operating manual
8.2 Mains connection
Power is supplied via the external mains adapter. The stated voltage value must be the
same as the local voltage.
Only use KERN original mains adapter. Using other makes requires consent by KERN.
8.3 Storage battery operation (optional)
The optionally supplied battery is charged with the supplied power supply.
Before the first use, the battery should be charged by connecting it to the mains power
supply for at least 15 hours.
If an arrow appears on the weight display above the battery symbol ,
the capacity of the rechargeable battery will soon be exhausted. The balance
will be ready to operate for about another 10 hours, then it will switch off
automatically. Charge the battery with the help of the supplied power pack.
If in the weight display appears „bat Lo“ followed by a flickering display, the
capacity of the rechargeable battery is below the prescribed minimum. The
balance will be ready to operate for about another 5 minutes, then it will switch
off automatically. Charge the battery with the help of the supplied power pack.
The LED display informs you during loading about the loading status of the rechargeable
battery.
red:
Battery is almost discharged
green:
Rechargeable battery completely reloaded

RFC-SH-e-1810
13
9 Adjustment
As the acceleration value due to gravity is not the same at every location on earth, each
balance must be coordinated - in compliance with the underlying physical weighing
principle - to the existing acceleration due to gravity at its place of location (only if the
balance has not already been adjusted to the location in the factory).This adjustment
process must be carried out for the first commissioning, after each change of location as
well as in case of fluctuating environment temperature.To receive accurate measuring
values it is also recommended to adjust the balance periodically in weighing operation.
The adjustment is locked for verified balances. Carrying out adjustment requires
that the seal is destroyed and the adjustment switch is confirmed in step 3 when
turning on the scale. For position of adjustment switch, see chap. 6.8.1
Attention:
After destruction of the seal the balance must be re-verified by an
authorised agency and a new verification wire/seal mark fitted before it can
be reused for applications subject to verification.
Procedure when adjusting:
Observe stable environmental conditions. A warming up time (see chapter 1) is
required for stabilization. Ensure that there are no objects on the weighing pan.
Arrange adjustment weight, details see chap.1 „Techn. data“
To turn on/off operate the on/off switch at the
underneath side on the right of the scale and
keep pressed for a little while. During the selftest
press and keep pressed until Pn is
displayed.
Use the numeric keys to enter the standard
password 0000. Pn---- is displayed.
Confirm password with , the adjustment
function F0 CAL will be displayed.
Press adjustment switch on the lower side of the balance.
Press , UnLoAd will be displayed. Ensure
that there are no objects on the weighing pan.
Press again, CAP LOADxx will be
displayed.
(example)

14 RFC-SH-e-1810
Set the displayed adjustment weight with the help
of .Place the adjustment weight.Wait for the
stability display appears,
then press .PASS will be displayed.Remove
the adjustment weight.F0 CAL appears on the
display.Now the process of adjustment is
successfully completed.Return to weighing mode
using
In case of an adjustment error or incorrect adjustment weight, the display will show
an error message (FAKLH), then repeat adjustment process.

RFC-SH-e-1810
15
10 Verification
UUGeneral hints:
According to EU directive 2014/31/EU balances must be officially verified if they are
used as follows (legally controlled area):
a) For commercial transactions if the price of goods is determined by weighing.
b) For the production of medicines in pharmacies as well as for analyses in the
medical and pharmaceutical laboratory.
c) For official purpose.
d) For manufacturing final packages.
In cases of doubt, please contact your local trade in standard.
After verification the balance is sealed at the indicated positions.
Verification of the balance is invalid without the "seals".
Verification notes
An EU type approval exists for balances described in their technical data as verifiable. If
a balance is used where obligation to verify exists as described above, it must be verified
and re-verified at regular intervals.
Re-verification of a balance is carried out according to the respective national
regulations. The validity for verification of balances in Germany is e.g. 2 years.
The legal regulation of the country where the balance is used must be observed!
Balances with obligation to verify must be taken out of operation if:
The weighing result of the balance is outside the error limit.Therefore,
in regular intervals load balance with known test weight (ca. 1/3 of the
max. load) and compare with displayed value.
The reverification deadline has been exceeded.

16 RFC-SH-e-1810
10.1 Adjustment switch and seals
1. Seal of approval
2. Adjustment switch
10.2 Checking the balance verification settings
For the adjustment, the balance must be switched over to service mode.
In the service mode the parameters of the balance can be modified.
If this happened accidentally, please contact KERN.
In verified scales the service mode is locked individually for each switch. To disable the
access lock, destroy the seal and actuate the switch.
Attention:
After destruction of the seal the balance must be re-verified by an authorised agency and
a new verification wire/seal mark fitted before it can be reused for applications subject to
verification.

RFC-SH-e-1810
17
11 The menu
11.1 Access to menu
To turn on/off operate the on/off switch at the
underneath side on the right of the scale and keep
pressed for a little while. During the selftest press
and keep pressed until the password inquiry "P in"
appears.
Using numeric keyboard, enter the standard password
"0000". "P in ----" is displayed.
Confirm with password, the adjustment
function F0 CAL will be displayed.
Press adjustment switch on the lower side of the balance
11.2 Navigation in the menu:
Use the numeric keys or to scroll up or down in the menu.
Confirm selected function by pressing . Select desired setting with or
and acknowledge by .
Exit menu:
Press the button as often as necessary until the zero display appears. The
balance is now again in weighing mode.

18 RFC-SH-e-1810
11.3 Menu overview
Function
Settings
or and
Description
or and
F0
CAL
Adjustment function
F1
rES
Resolution
Press adjustment switch
rES dUAL-i
rES dUAL-r
3000
6000
F2
CAP
Weighing range (max)
30KG
3KG
6KG
15KG
F3
PdECi
Decimal point price
PdSL 0.00
PdSL 0.000
PdSL 0.0000
PdSL 0
F4
PdESC
not documented
PdESC Fix
PdESC FLoAt
F5
SPEEd
A/D converter
SLow
MEdiuM
FASt
F6
Min Coin
Interval size currency
Coin 1 Coin
Coin 2 Coin
Coin 5 Coin
Coin 10 Coin
F7
SCSiUE tArE
Multi-Tare function
S tArE oFF
S tArE on
F8
iSn
Internal value
iSnxxxxx

RFC-SH-e-1810
19
F9
GrA
Gravity
GrA x.xxxxx
F10
rESEt
Back to factory setting
F11
rS232
Interface RS232
ModE
oFF
Cont
Continuous data transfer
StC
Stable value continuous
toLEdo
Log Type 1
nCiECr
Log Type 2
nCiGEn
Log Type 3
tEC
Log Type 4
EASY
Log Type 5
PrintEr
Printout via printer
tPuP
Printout by pressing
LP50
Printout by pressing
PoS
not documented
bAUd
Baud rate
9600
19200
38400
115200
1200
2400
4800
Pr
8n1
8 data bits, no parity, 1 stop bit
7E1
7 data bits, even parity, 1 stop bit
7o1
7 data bits, odd parity, 1 stop bit

20 RFC-SH-e-1810
12 Instant help
In case of an error in the program process, briefly turn off the balance and
disconnect from power supply. The weighing process must then be restarted
from the beginning.
Fault
Possible cause
The displayed weight does not
glow.
The balance is not switched on.
The mains supply connection has been interrupted
(mains cable not plugged in/faulty).
Power supply interrupted.
Batteries are inserted incorrectly or empty
No batteries inserted.
The displayed weight is
permanently changing
Draught/air movement
Glass doors not closed
Table/floor vibrations
Weighing pan has contact with other objects.
Electromagnetic fields / static charging (choose different
location/switch off interfering device if possible)
The weighing result is
obviously incorrect
The display of the balance is not at zero
Adjustment is no longer correct.
The balance is on an uneven surface.
Great fluctuations in temperature.
Electromagnetic fields / static charging (choose different
location/switch off interfering device if possible)
Should other error messages occur, switch balance off and then on again. If the error
message remains inform manufacturer.