Adam Equipment CBK-M Series User manual

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Adam Equipment
CBK-M SERIES
Service Manual
Software rev.: 4.07 & above
ADAM EQUIPMENT CO. LTD.
P.N. 9017, Rev. A2, July 2007
© Adam Equipment Company 2007

© Adam Equipment Company 2007

© Adam Equipment Company 2007 1
CONTENTS
1.0 INTRODUCTION.......................................................................................................2
2.0 SPECIFICATIONS....................................................................................................3
3.0 TROUBLESHOOTING..............................................................................................4
4.0 ERROR CODES .......................................................................................................5
5.0 CBK-M DESCRIPTION.............................................................................................6
6.0 LOAD CELL DAMAGE..............................................................................................6
7.0 CALIBRATION..........................................................................................................9
7.1 SECURITY SEALS..............................................................................................10
7.2 CALIBRATION PROCEDURE.............................................................................10
8.0 FACTORY PARAMETERS .....................................................................................11
8.1 F1 -CALIBRATION................................................................................................12
8.2 F2 -RESOLUTION................................................................................................13
8.3 F3 –CAPACITY....................................................................................................13
8.4 F4 -INITIAL ZERO RANGE...................................................................................13
8.5 F5 -RE-ZERO RANGE .........................................................................................14
8.6 F6 -SUCCESSIVE TARE......................................................................................14
8.7 F7 -A/D COUNT....................................................................................................15
8.8 F8 –ZERO ............................................................................................................15
8.9 F9 –LOW VOLTAGE DETECTION.......................................................................16
9.0 WIRING DIAGRAM.................................................................................................17
10.0 MECHANICAL ASSEMBLY ....................................................................................18
*****

1.0 INTRODUCTION
•The CBK-M series of scales provide an accurate, fast and versatile general
purpose weighing scales with counting, percent weighing and check-
weighing functions.
•CBK-M scales are kilogram only scales.
•There are 4 models with capacities up to 30kg.
•The scales have LEDs to indicate when a weight is below the low limit,
between the limits or above the high limit next to the display. These can
work in conjunction with an audible alarm for check weighing as well as LCD
showing LO, OK and HI.
•The scales have stainless steel weighing platforms on an ABS base
assembly.
•All scales are supplied with a RS-232 bi-directional interface and real time
clock (RTC). NOTE: For Approved applications, CBK-M Scales do not come
with the RS-232 interface. However, the scales can be supplied with RS-232
interface if they are not to be used for approved applications.
•The scales have sealed keypads with colour coded membrane switches and
a large easy to read liquid crystal type display (LCD) supplied with a
backlight.
•The scales include automatic zero tracking, semi-automatic tare,
accumulation facility that allows the count and weight to be stored and
recalled as an accumulated total.
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© Adam Equipment Company 2007 3
2.0 SPECIFICATIONS
CBK 3M CBK 6M CBK 15M CBK 30M
Grams
Max 3000 g 6000 g 15000 g 30000 g
d = 1 g 2 g 5 g 10 g
n = 3000 3000 3000 3000
Kilograms
Max 3kg 6kg 15kg 30 kg
d = 0.001kg 0.002kg 0.005kg 0.01 kg
OTHER SPECIFICATIONS
Units of measure Kg, g
Interface RS-232 bi-directional Interface
NOTE: For Approved applications, CBK-M Scales do not come with the RS-232
interface. However, the scales can be supplied with RS-232 interface if they are
not to be used for approved applications.
Stabilisation Time 2 Seconds typical
Operating Temperature -10°C to 40°C / 14°F to 104°F
Power supply 115/230 VAC Mains, 50/60 Hz
or 9 VDC, 800 mA through an external adapter
Battery Internal rechargeable battery (~90 hours operation)
Calibration Not available
Display 6 digits LCD digital display
with capacity tracker and symbol for unit
Scale Housing ABS Plastic, Stainless Steel platform
Pan Size 225 x 275 mm / 8.9” x 10.8”
Overall Dimensions
(wxdxh) 315 x 355 x 110 mm
12.4” x 14” x 4.3”
Net Weight 4.1 kg / 9 lb
Applications Weighing Scales
Functions Weighing, Parts counting, % weighing, Check weighing,
Check counting, Accumulation of weights
Date/Time Real Time Clock (RTC),
To print date and time information- battery backed.
NOTE: For Approved applications, CBK-M Scales do not come with
the RS-232 interface.

© Adam Equipment Company 2007 4
3.0 TROUBLESHOOTING
PROBLEM POSSIBLE CAUSE
Display is blank Power Switch faulty or not connected
No turn on test Battery not charged or faulty
Power supply faulty or incorrect type
“- - - - - -“appears on display Maximum capacity exceeded
Load Cell damaged
Electronics is faulty
Display is unstable Drafts or air currents
Obstruction under pan
Sample is moving (animal weighing)
Vibrations through table
Temperature changed dramatically
Electronics faulty or Battery low
Weight value incorrect Calibration error, Recalibrate
Unit calibrated with inaccurate weight
Balance not level
Obstruction between sample pan
Wrong unit of weight displayed
Cannot use Full Capacity Over-load Stops hitting pan support or hitting
bottom of load cell
Electronics faulty
Parameters set incorrectly
Load Cell Damaged
Not Linear Overload stops hitting too soon
Faulty factory calibration

© Adam Equipment Company 2007 5
Off Centre Loading error Overload Stops not correct
Obstruction under pan
Battery will not charge Charging circuit failure
BatteryFailure
Incorrect adapter (below 800 mA)
Processor failure
4.0 ERROR CODES
ERROR
CODE DESCRIPTION POSSIBLE CAUSES
Err 1* Time input Error Invalid time entry such as “268970” for
the time format “H-m-S”.
Err 2* Date input Error 34th day of a month is an invalid entry.
Err 4 Initial Zero is greater than
allowed (4% of maximum
capacity) when power is turned
on or when the [Zero/Enter]
key is pressed.
Weight on the pan when turning the
scale on.
Excessive weight on the pan when
zeroing the scale.
Platform is not installed.
Improper calibration of the scale.
Damaged load cell.
Damaged Electronics.
Err6 A/D count is not correct when
turning the scale on. Load cell is damaged. Electronics is damaged.
Err7 Percent input error Percent function is entered with no
reference mass on the pan.
Err 8 High limit input error Low limit is set first, then the high limit is
set lower than the low limit and high
limit not equal to zero.
Err9 Low limit input error High limit is set first, then the low limit is
set higher than the high limit and low
limit not equal to zero.
FAILHor
FAILL Calibration error Improper factory calibration). The old
calibration data will be retained until the
calibration process is complete.
*Err 1 and Err2are not applicable for scales used in approved applications.

© Adam Equipment Company 2007 6
5.0 CBK-M DESCRIPTION
The CBK-M scales have an enclosure with all components mounted within it. To gain
access to the components remove the 5 screws securing the cover to the base.
The basic unit consists of:
9Base
9Load Cell frame
9Power switch
9Main PCB assembly
9Battery
9Display PCB assembly
9Keypad
All models of CBK-M are similar except the selection of load cells and the program.
Normally if a problem is found with a circuit board the most cost effective method of
solving the problem is to replace the circuit board.
The main PCB assembly includes:
9A/D converter (AU1),
9Microprocessor (DU1) and
9Power supply/battery charger circuits (DU5, T2).
6.0 LOAD CELL DAMAGE
The most common reason why a scale fails is that the load cell has been damaged. The
damage can be from 2 primary causes. The first is physical damage due to an overload or
an impact from the side and the second is damage due to the environment, such as
moisture, extreme heat or a cut cable if the cables are exposed.
PRINCIPLE OF OPERATION
The stain gauge load cell is a method of measuring the amount of stress put onto a metal
structure due to a weight being supported by the structure. The stress is measured using
4 strain gauge sensors mounted in a particular way on the metal structure.
These 4 strain gauges are connected in such a way that they form a Wheatstone Bridge.
See figure below. In the simplest load cells there are only the 4 resistances of the strain

gauges to consider. Normally without a load on the load cell all the resistances are the
same. However when the load cell has a weight on it 2 of the strain gages will be in
compression (A and D) and the resistance will decrease and 2 will be in tension (B and C)
and their resistance will increase.
350 ohm
350 ohm
350ohm
350ohm
AB
CD
+E
-S
-E
+S
BALANCED BRIDGE
10 VOLT POWER
SUPPLY
Vout = O VOLTS,
BETWEEN +S AND -s
351ohm
349ohm
351ohm
349ohm
AB
CD
+E
-S
-E
+S
UNBALANCED BRIDGE
FULL CAPACITY LOAD
ON THE LOAD CELL
10 VOLT POWER
SUPPLY
Vout = 0.028 VOLTS (28mv),
BETWEEN +S AND -s
This will cause the bridge to become unbalanced. When the bridge has a voltage across it
from +E to -E then the signal output at +S and -S will show a voltage of zero volts with no
load and a small voltage proportional to the load as the load is increased. Typical load
cells show 20-30mv of signal if the excitation voltage is 10volts and the load cell is fully
loaded.
Most load cells used in scales are not as simple as this example. They have additional
resistance elements added to compensate for temperature variations and to set the
outputs to correct voltages. The circuit of a typical load cell is shown below-
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A method to check the basic function and integrity of a load cell can be done using a
ohmmeter and voltmeter with up to a 10volt power supply.
Before the load cell is connected to the power supply use the ohmmeter to measure the
resistance between the wires. Typical resistance values are:
+E to -E 410 ohms ±30 ohms
+S to -S 350 ohms ± 2 ohms
+E to +S or any other combination similar approximately 270 ohms.
If the load cell has Sense connections in addition they are connected to the excitation
internal to the load cell.
Connect the load cell +E and -E to a power supply, typically 10 volts. Never use more
than 12 volts as it may damage the load cell.
Measure the voltage between +S and -S.
With no load the voltage should be approximate 0mv ±3mv.
With a mass on the load cell the output voltage should increase. The amount by which it
increases will be dependent upon the sensitivity of the load cell, capacity of the load cell,
the excitation voltage and the amount of mass placed on the load cell. Most load cells
have a sensitivity of either 2mv/V or 3mv/V.
The expected change to the output is:
Vout = (2mv/V) * Vext * Mass
capacity of load cell
For example a 2mv/V load cell of 30Kg capacity with 20Kg placed on it. Vext is 5 volts
would give a output of approximately:
Vout = (2mv/V) * Vext * Mass = 2mv/V * 5V * 20Kg = 6.7mv
capacity of load cell 30kg
If the load cell has been damaged the no load voltage will likely be greater than 3mv or the
loaded voltage will be grossly different from the expected value. Remember the loaded
voltage will be offset by the amount of zero load voltage measured.