MAGUIRE FLEXBUS Lite, Installation Operation & Maintenance

Page: 93 / 143

93
VERIFYING LOAD CELL FUNCTION
Most Problems are related to LOAD CELL function.
There are several ways to VERIFY that the load cells are functioning properly. The slightest touch
on the weigh bin should result in a change in the readout. If this is not the case, something is
wrong. When the light touch is removed, the display should return to its starting point. If this does
not happen, something is interfering with free movement of the cell or the bin. Make a careful
inspection of EVERYTHING around the load cells, the hanger bolts, the weigh bin tray and the
weigh bin. NOTHING should interfere with free movement.
It is normal for load cell readout to drift several grams over time and with different
temperatures. Since all the component dispenses are weighed by a single set of
load cells, this drift will affect all components equally and, therefore, the ratio of
the components will remain accurate. Empty weight is always TARED so each
dispense is accurately measured.
The following observations will verify proper load cell operation:
When the bin is empty, between cycles, the display should read near zero. An error of several
grams is not important since this empty weight reading is "tared" at the start of a cycle. The
"empty weight" readings should be consistently within 1 or 2 grams of each other.
The addition of several pellets to the weigh bin should result in a change in the readout. 1 gram is
about 40 pellets.
Most load cell problems are caused by interference to the movement of the load cell. The load
cell must be free to respond to the weight of a single pellet as well as free to move far enough to
record a full 20,000 gram weight deflection. (10,000 grams per cell - 10K cells)
If weight readout is very erratic check for damage to the load cell wires. Check for a pinched wire
in the connector.
An over stressed load cell will read high. The top limit is 3100.0 for a 200 series or 31000 for a 400
or 900 series. A load cell that was forced or pried upward too far will read 0.0.
We supply and replace load cells in matched sets and we always include the mounting
enclosures. You may remove the back plate from the enclosure for visual inspection. It is not
safe to remove the load cell itself from the enclosure. To do so may stress the cell itself.
To OPERATE with DAMAGED load cells in a VOLUMETRIC mode, see Volumetric Operation on
page 68.
To RECALIBRATE the LOAD CELLS, see the Load Cell Recalibration on page 68.
If you suspect load cell damage or failure, see: LOAD CELL RAW SIGNAL READOUT.