Quantronix CUBISCAN 325, Service Manual

Page: 34 / 98

BALANCING THE LOAD CELLS Balancing the load cells
Cubiscan 325 Service Manual 2 4
6. Remove the eight screws holding the load cell
summing board lid in place and remove the lid.
Refer to
Figure 13 .
7. To balance the load cells you will need to adjust the
variable resistors, which are also known as
potentiometers or POT’s. To adjust a POT, use the
small flathead screwdriver to rotate the screw. See
Figure 14 .
Rotating a POT clockwise will increase the added
weight from a load cell.
Rotating a POT counterclockwise will decrease the
added weight from a load cell.
Adjusting a POT will affect the other 3 POT readings.
The goal is to have all four corners display the same
weight value.
If you are ever adjusting a POT and hear a quiet
clicking, or notice that the weight value is not
changing when you make adjustments, you will need
to center that particular POT. Center the POT by
turning it at least 25 times in the same direction.
Then turn the POT the opposite direction 12 times.
The POT should now be centered.
8. Place the 25 lb weight on each corner of the
Cubiscan 325. Record all four values. Figure 15
shows which Cubiscan 325 corner (where the load
cells are located) corresponds with each POT.
9. Choose the two corners that are closest to 25 lb.
These will be your first and second corners. Move
the weight back and forth between them. Adjust the
appropriate POT until the displayed weight values
for both corners are the same (this does not
necessarily need to be exactly 25 lb).
10. Choose your third corner. Move the weight back and
forth between corners one and three. Adjust the
POT’s until the same weight value is displayed for all
three of your selected corners.
11. Now move the weight to the fourth corner. Move the
weight back and forth between corners one and four.
Adjust the POT for corner four until the displayed
weight values are the same for each corner.
Figure 14
POT’s (Potentiometers)
Figure 15
Load cell wire connections
POTS