PS250
Service Manual
PS250 Services Manual
Page 1 of 11
Content
Scale Key layout
Page 3
Configuration settings
Page 3
RS232 Set up
page 5
Calibration procedure
Page 6
Gravity compensation
Page 7
Main Error messages
Page 8
General Fault finding
Page 8
Standard Repairs
page 9
Spare parts
page 11
PS250 Services Manual
Page 2 of 11
Scale Key layout
O N -O F F
N et
HOLD
U N IT S
kg
H o ld
ZERO
0
2 5 0 k g x 0 . 1 k g / 5 5 0 l b x 0 . 2 lb
TARE
T
PS250
Tare Key
Used to tare off the weight of a animal cage / container that
is placed on the scale.
On / Zero / Off key
Press once to turn on and Zero the scale.
Press once when scale is on to re-zero the scales display.
Press and Hold key will turn off scale
Units key
Toggles between the units of measure that the scale has
been configured to.
Hold key
when pressed the scale will average out the weight
Before holding this reading on the display.
If linked to a printer of PC the Held weight will be
automatically transmitted once the hold enunciator has been
activated.
Press a second time to release the hold function
Configuration settings
To get into the scales configuration menu first switches on the scale. Once the scale is on
press and hold the tare key until the display shows Set and then Unit.
Unit key
Hold key
Moves display to the right
Moves the display up /down or accept a change.
To exit move through the Set up menu until you get to the End.
When the End is displayed press the Hold key to accept changes.
Scale will return back to weight mode
Press & Hold Tare Key
PS250 Services Manual
Page 3 of 11
Set Unit
Unit Setting Function
Allows you to turn off or on the following units of measure. kg, lb, oz
(Default kg on, lb on , oz on )
AOFF
Auto Off Function
Enable Auto off the time delay to be changed. 120 sec, 240 sec, 300 sec and
(Default 120)
Off.
Off setting will turn off this auto off function allowing the scale to remain on
until the off key has been pressed.
Cap
Capacity setting
Enable the scale capacity to be change without the need for re-calibration.
250kg or 300kg. (Default 250kg)
CAL
Calibration Settings
Enables the scale to be re-calibrated at full load ½ load or ¼ load.
(Default FULL)
Weighing
units
kg
lb
Full load
½ load
¼ load
200kg
500lb
100kg
200lb
50kg
100lb
DivS
Division Setting
Enable the scale division to be changed without the need of re-calibrating the
scale: 1500 d, 3000d or 6000d (Default 3000 d)
GrAv
Gravity Compensation
For scales that are used out side Europe the gravity compensation can be
activated.
This will allow the operator to enter the pacific gravity of where the scale is to
be used without the need for re-calibrating the scale: On or Off (Default off)
See Gravity Compensation on page
TrAn
RS232 data transmission
Enable the PS250 to communicate to a basic printer of PC: d\n 1, d\n2 or off
(Default off)
d\n1
RS232 data transmission on continuous output
Will continually transmit the net weight of the scale
Data output string: (+/-)( )( )( )(Net weight)( )( )( )(unit of measure)(Line
Feed)(Carriage Return)(End of Text)
d\n 2, RS232 data transmission on demand
Allows the displayed data to be sent to a PC / printer once the hold
key has been pressed and the weight on the display has stabilised.
Data output string: (+/-)( )( )( )(displayed weight) ( )( )( )(unit of measure)
(Line Feed)(Carriage Return)(End of Text)
Off
Tr
Will deactivate the RS232 data output signal.
Board rate Transmission settings
Enables the operator to easily change the scales board rates settings from
2400, 4800, 9600 19200. (Default 2400)
Fixed data transmission setting: Data Bits: 8, Parity: None, Stop Bits: 1
End
By pressing the Hold key when the end is displayed will save all change and
switch back to normal weigh mode.
PS250 Services Manual
Page 4 of 11
RS232 Set up –This may not be available on your unit.
To connect the PS250 to a PC or basic printer first set up the PS250 to send the data
continuously (n\d1) or on command (n\d2).
In set up mode select TrAn and then select whether you want to data to be
transmitted continuously (n\d1) or on command (n\d2) and press hold to save.
Move to Tr and select the board rate you want the data to be transmitted at and then
press hold to save.
Move to End and press hold to save setting and exit back to weight mode.
Plug in the RS232 data lead (EDA908) to the side of the PS250 Head and the back of
the PC.
Testing data transmission
Open up HyperTerminal on the PC and set board rates as follows
Board rate (as selected) Data Bits: 8, Parity: None, Stop Bits: 1
Switch on scale, place a weight on the platform and press hold key, scale data should
now be displayed on the PC screen.
-
102.2
105.0
98.0
99.0
24.1
28.0
kg
kg
kg
kg
kg
kg
RS232 lead connections
(PS250 end )
9 way D-type (plug) connector
Pin 2
(TXD)
Pin 3
(RXD)
Pin 5 (Ground)
EDA-908
Wiring
White
Red
Yellow
(PC end)
9 way D-type (Socket) connector
Pin 2
(RXD)
Pin 3
(TXD)
Pin 5 (Ground)
Fault finding
Scale not transmitting data.
• Check PS250 configuration settings to make sure that the RS232 is
switched on.
• Check PC and PS250 Board rate are the same.
• Check PC Port settings
• Check pin connections are correct.
• Test lead for brakes in cable
• Test scale data with HyperTerminal
• Check Ps250 RS232 wiring by removing left-hand end cap.
• If scale is still not transmitting data replace PS250 head unit and
recalibrate
PS250 Services Manual
Page 5 of 11
Calibration procedure
In set up mode select CaL and then select whether you want to calibrate the scale to
full load ½ load or ¼ load and save change.
Weighing
units
kg
lb
Full load
½ load
¼ load
200kg
500lb
100kg
200lb
50kg
100lb
Switch off the scale.
Press and hold the ON-OFF key with one hand. You will see 8”s come up across
the display. Note: DO NOT release the on key at this time.
While still holding the ON-OFF key use your other hand and press the Units key 3
times, you must release the ON-Off key at the same time as you release the UNITS
key for the third time. Scale will display a 0 on the left hand side of the display
and will show a zero count value between 500 to 8000 on the right hand side of
the display.
Press the Tare key to save the zero count value. Scale will now display 0 kg.
Press the Units key to select the unit of measure the scale is to be calibrated in.
Place the required calibration weight on the platform and press Tare. The scale will
Display Cal for a few seconds before displaying the correct weight.
With 200kg on the platform the spanned counts should be between 8000 to 20000
counts. Note: If the counts are outside this tolerance range the Resistance over R1,
R2 on display PCB will have to change. Contact Service for further assistance.
Press and hold the ON-OFF key to shut off the scale, this completes the calibration of
the scale.
PS250 Services Manual
Page 6 of 11
Gravity compensation
This will allow the operator to enter the pacific gravity of where the scale is to be used
without the need for re-calibrating the scale.
70°
60°
50°
40°
30°
20°
10°
0°
10°
20°
30°
40°
50°
Latitude
70°
60°
50°
40°
30°
20°
10°
0°
General gravity
zones based at
sea level
9.826
9.819
9.810
9.801
9.793
9.786
9.781
9.780
Expected error at
full load 250kg
4 divisions
2 divisions
0 divisions
-3 divisions
-5 divisions
-7 divisions
-8 divisions
-8 divisions
To activate this function enter the set up mode select GrAv, and then select on.
Switch off the scale.
Press and hold the on key, at the same time press the Units key 3 times before
releasing the on key. Scale will now display the gravity the scale was last calibrated in
To adjust the gravity use the units key to increase
the number and the hold key to move to the next
Digit.
9.811
Press the Tare Key to accept the newly entered gravity setting and then turn off
scale.
Scale will now switch on and operate to the newly entered gravity.
PS250 Services Manual
Page 7 of 11
Main Error messages
Bat Low
Err
Errl
ErrE
Battery needs charging
Overload
Below Zero
EPROM error
General Fault finding
No display
Mainly due to loss of power
• Recharge scale with power adapter.
• Test or change power adapter
• Replace battery
Bat low enunciator not turning off
• Recharge scale with power adapter
• Test or change power adapter
• Replace battery.
Err
Normally indicates that the scale is over capacity or the load cell data is not getting to
the Indicator head.
• Check that the indicator is correctly attached to the platform.
• Check for lose wires in the indicator plug.
• Check for lose wires the platform socket.
• Measure mV reading across load cell signal wires to determine if one of the load
cell is faulty. If a big discrepancy is registered replace complete loadcell base
and recalibrate.
• Display Head unit must be faulty, Replace with new Head unit and recalibrate
scale.
Errl
Normally indicates that the zero counts have moved due to a faulty loadcell on the
platform.
• Attempt to re-calibration
• Measure mV reading across load cell signal wires to determine if one of the load
cell is faulty. If a big discrepancy is registered replace complete loadcell base
and recalibrate.
Scale showing unstable reading
• Check that the platforms not catching on something.
• Check that vibration or air movement is not affecting the scale i.e: Ventilation
fans, heaters open doors.
• Measure mV reading across load cell signal wires to determine if one of the load
cell is faulty. If a big discrepancy is registered replace complete loadcell base
and recalibrate.
• Display Head unit must be faulty, Replace with new Head unit and recalibrate
scale.
Scale not returning to zero
• Check that the platforms not catching on a wall or that something is trapped
underneath the scale.
• Measure mV reading across load cell signal wires to determine if one of the load
cell is faulty. If a big discrepancy is registered replace complete loadcell base
and recalibrate.
• Display Head unit must be faulty, Replace with new Head unit and recalibrate
scale.
PS250 Services Manual
Page 8 of 11
Hold function will not work
• Check to see it the stable enunciator comes on.
• Check to see if the hold enunciator comes on when pressed.
• Check that the animal being weighed is not to light (Hold will not operate under
4kg)
• Check hold feature works with a non-moving object
• Measure mV reading across load cell signal wires to determine if one of the load
cell is faulty. If a big discrepancy is registered replace complete loadcell base
and recalibrate.
• Display Head unit must be faulty, Replace with new Head unit and recalibrate
scale.
Scale will not auto-switch off
• Check in the set up mode to insure that the Auto off is not set to off.
• Check that the scale is not left in set up mode.
Standard Repairs
Replacing Display head
Unplug faulty display head from base and
Reconnect with new one.
Recalibrate scale as shown in the calibration
section of this manual.
Battery replacement
Undo the two screws on the right hand side end cap
of the display head.
Ease out the display PCB from the display housing
by gently pulling on the loadcell cabling.
Battery
lead
Unplug the old battery from the side on the display
PCB and replace with new battery.
Screw slots
Slide display PCB back into the display housing
insuring that the PCB is located within the two screw slots.
Replace the PCB location rod back into one of the screw
slots and push PCB back in to position.
Push replacement battery back into the side of the
display housing and replace end cap.
Recharge battery prior to using.
PS250 Services Manual
Page 9 of 11
Load cell base replacement
Unplug faulty base from display head unit.
Remove the four-loadcell feet
Unscrew the four top cover screws found on the side
of the platform.
Remove the faulty loadcell base frame from the top
cover and replace with new one.
Replace the top cover screws and plug in the display
head unit.
Recalibrate scale as shown in the calibration section of this manual.
Display head cable wiring
Display
Head Plug
PIN 1
PIN 2
PIN 3
PIN 4
PIN 5
+ 5V
+ Sig
- Sig
Ground
Wire
colours
RED
GREEN
WHITE
BLUE
Testing Platform for faulty loadcell
Remove top cover by undoing side screws.
With the scale turned on measure Excitation mV reading across black and red wires,
which come from the plug socket. This should read 5V
Then check the signal reading by measuring the mV reading across the LW2 ( -Sig)
and ground , The mV reading should increase evenly when weight applied
Then check the other signal reading by measuring the mV reading across the LW3
( +Sig) and ground , This mV reading should also increase evenly when weight
applied
Ground
LW2 ( -Sig)
LW3 (+ Sig)
If for some reason the mV reading is seen to be erratic or remain at 0 mV would
indicate that one of the loadcell have been damaged. To repair this replace loadcell
base frame as mentioned in the Load cell base replacement section of this manual.
PS250 Services Manual
Page 10 of 11
PS250 Parts list
Part number
Picture
52739-0132
Replacement Display
Head
52739-0512 – PS250-22S
52739-0520 - PS250-36
52739-0538 - PS250-36S
52739-0546 - PS250-42
52739-0553 - PS250-42S
Loadcell & Base frame
816965000890
Battery
52739-0587
One Foot
120VAC, 9W, 15VDC,
300ma AC adapter
(new style)
816965000906
52739-0355
PS250 Services Manual
Description
Power adapter (old
style)
Page 11 of 11
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