Non-Functioning Key(S); Preparing For Calibration; Entering The Calibration Mode - Grainger 4802 Operating And Service Manual

when measured from its terminals.
4.36

NON-FUNCTIONING KEY(S)

Check the front panel keyboard for visible signs of
damage (punctures, dents, etc.).
keyboard tail with connector is properly inserted into
the display board.
If a particular function does not work (example: no
kilogram units) check if that particular function is
turned off in the "SET-UP" mode (see section 2.40)
REMEMBER: Some hospitals have specified that
the scale weigh in kilograms ONLY-- this should not
be modified or changed.
4.37 ERROR
"E-FAIL" OR "r-FAIL"
This indicates a
mircocomputer's memory during the start-up self-test.
"E-FAIL" indicates a failure of the microcomputer's
EPROM memory during the checksum test. "r-FAIL"
shows a failure of the random access memory. Both
conditions require replacement of the microcomputer.
4.40 CALIBRATION
Your scale has been carefully calibrated at the
factory. This calibration involves matching and tuning
of the load cells and readout electronics. Since there
are no moving parts in the weighing mechanism there
should never be a need to recalibrate the scale.
Errors are typically caused by external interference or
forces. We suggest that the scale calibration be
checked annually. Only use calibrated, certified scale
test weights for this purpose. Traction or physical
therapy weights are NOT ACCEPTABLE SINCE
THEIR ACTUAL WEIGHT CAN OFTEN BE IN
ERROR AS MUCH AS +/-10%. Calibration weights
may be purchased from SCALE-TRONIX® or a local
scale dealer. An alternative to calibration weights is
the weight comparison method.
known accurate, calibrated scale. A fixed weight is
"weighed" on the calibrated scale; then the same
weight is placed on the scale for comparison.
PRECISION TEST CALIBRATION WEIGHTS ARE
AVAILABLE FROM SCALE-TRONIX®.
TWO (2) 10 KILOGRAM TEST WEIGHTS ARE
RECOMMENDED.
ORDER PART NO. 390025 / 20022: 10 kilogram
test weight (1)
Check that
MESSAGE DISPLAYED:
failure of the
This requires a
If only "pound" test weights are available, conversion
is as follows:
Large changes in calibration often indicate a
damaged load cell or faulty readout component. It is
generally
necessary for your scale that it should be returned to
the factory. Calibration procedure follows for those
situations where this is not desirable.
should not be attempted by those not having the
proper tools or knowledge of electronic systems and
their attendant shock hazards.
4.41
internal
Unplug the scale from the AC line. Unplug the cradle
from the scale. Detach the top cover of the scale's
enclosure by removing the eight (8) #10 button head
screws. The scale's instrument board should now be
in full view.
potentiometer, "P1 Span".
4.42
Enter the "calibration mode" by following exactly the
procedure outlined below:
1. Be sure scale is off.
2. Press
3. While pressing the "REWEIGH" pushbutton,
4. NOTE: The "Print/Send/Data" pushbutton is
5. Press the "Print/Send/Data" pushbutton
18
1.0 Pound = 0.454 Kilograms
5.0 Pounds = 2.268 Kilograms
10.0 Pounds = 4.536 Kilograms
20.0 Pounds = 9.072 Kilograms
25.0 Pounds = 11.34 Kilograms
recommended that

PREPARING FOR CALIBRATION

Note the location of the trimmer

ENTERING THE CALIBRATION MODE

and hold
pushbutton.
press and release the "ON / (OFF) / ZERO"
pushbutton.
a special hidden programming and test
pushbutton located to the right of the front
panel "RECALL
pushbutton. After the scale displays the test
pattern of "888888" release the "REWEIGH"
button and press the "Print/Send/Data"
pushbutton five (5) times. This will cause the
readout to enter the calibration mode. The
display will indicate "CAL".
once more; the display will indicate "A-d".
This indicates the start of the "raw"
if calibration is
Calibration
in the "REWEIGH"
PRIOR WEIGHT"