Maguire Products Weigh Scale Blender WSB, Руководство по эксплуатации и техническому обслуживанию

Страница: 78 / 99

M A G U I R E P R O D U C T S , I N C .
Edition: August 6, 2014
78
W E I G H S C A L E B L E N D E R
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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" from all dispense readings. 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 38.
To RECALIBRATE the LOAD CELLS, see the Load Cell Recalibration on page 82.
If you suspect load cell damage or failure, see: LOAD CELL RAW SIGNAL READOUT.
Load Cell Raw Signal Readout
Press Options, Special Functions, Diagnostics, Load Cell Diagnostics to check this RAW number for several seconds.
Load cells put out a very small voltage that varies slightly as the load cell is deflected. This voltage is converted, on the circuit
board, to a pulse train and these pulses are counted for 1 full second to determine a weight load. The software can handle a
range of counts from 0 to approximately 249,850.
A properly operating set of 3 K cells will range from about 55,000 to 120,000; a span of about 65,000 from empty weight (weigh
bin in place), to a full bin weight of 2000 grams. (10 K load cells range about 90,000 from empty to a full 9000 grams). The system
will work correctly as long as the empty bin weight readout is between 1 and 149,248. 149,248 is the highest number that the
software will accept for zero weight calibration (see parameters, LCZ). If the number is over this when you press the ZERO weight
key, the display will say (ZERO LOW).
This RAW COUNT number is converted to the proper gram readout, by the software, based on load cell calibration information.
The RAW COUNT numbers are more useful in diagnosing load cell problems because they bypass the calibration math and,
therefore, bypass any calibration errors that might have occurred.
To enable the Raw Signal Readout, press Options, enter password (22222 is the default password), press Special Functions,
Diagnostics, Load Cell Diagnostics. Select ADC capture to enable/disable. Press EXIT 4 times to get out of program mode.