Calibration And Adjustments; Cal Mode General Information - ConMed Sabre 2400 Operators & Service Manual

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6. Set the DRB to 7 ohms and confirm that
the Resistance Indicator is dark and the Return
Monitor is lit.
7. Select Single Foil Mode. Confirm the
Resistance Indicator stops flashing and the
Return Monitor is not illuminated.
8. Increase the DRB in 1 ohm steps until an
audible Return Fault Alarm is sounded and the
Return Fault Indicator is lit. Confirm the DRB is
between 8 and 12 ohms.
9. Decrease the DRB setting in 1 ohm steps until
the Return Fault Indicator goes dark. Confirm
that the DRB reads from 1 to 4 ohms less than
the resistance read in Step 8.
10. Disconnect the DRB. This completes the
A.R.M. calibration test. If any readings were only
slightly out of range, first check the DRB with
an accurate ohmmeter. If the DRB is accurate,
recalibrate the A.R.M. limits in CAL Mode. See
Section 4.6.4. If one or more readings were far
from the mark, troubleshoot the A.R.M. circuitry
before attempting recalibration. See Section
4.7.6.

4.6 CALIBRATION AND ADJUSTMENTS

The Sabre 2400 is calibrated without selecting
or adjusting components. Instead, calibration
factors necessary to compensate for unit-to-unit
circuit variations are stored digitally in an electri-
cally erasable programmable read only memory
(EEPROM) A2U4. This device contains the
VBASE drive vs. output power lookup tables for
each of the operational modes, and the VARM
values for the upper and lower allowable resis-
tance limits of the dual foil return circuit.
The EEPROM contents remain intact for years
with no power applied, and redundant hard-
ware and software are used to prevent changing
EEPROM data in normal use. On every power
up and during normal operation, the integrity of
the EEPROM contents is validated using a Cyclic
Redundancy Check (CRC). Failure of the stored
EEPROM CRC to match the computed value
will result in declaration of a HLP-3 Fault code
and shutdown of all output.
4-8
A special operational mode, called CAL Mode,
permits the EEPROM data to be updated to
compensate for circuit performance changes due
to aging or replacement of components. In CAL
Mode, the microprocessor guides the technician
to simplify and expedite a complete and accurate
calibration. A second function "dIA" may also be
selected in CAL mode. See sections 4.7.2 and
4.7.3 for an explanation of its function.
NOTE: CAL Mode should not be used to per-
form routine calibration checks. Those tests are
better conducted in RUN Mode per Sections
4.5.3 and 4.5.7. If the unit proves to be out of
calibration, the possibility of a component failure
should be eliminated as the cause before recali-
brating. Once the physical health of the unit as
been confirmed, then CAL Mode may be entered
to correct the calibration.

4.6.1 CAL Mode General Information.

CAUTION: Do not enter CAL Mode without
first reading and understanding the follow-
ing material and ensuring that the necessary
equipment is on hand and accurate. Improper
calibration procedures can cause an otherwise
serviceable unit to become unusable until cali-
bration is corrected.
• On initial entry to CAL Mode, a calibration
validity test is done. If the test passes, then all
points in all modes are considered calibrated; if it
fails, ALL points are declared uncalibrated, and
the EEPROM is loaded with a set of nominal val-
ues which will bring a properly functioning unit
within range of its required calibration. The unit
will be unserviceable until fully recalibrated.
• If nonmonotonicity is detected on exit from a
Calibration mode, a HLP-11 code is displayed,
and all of the calibration points for the nonmono-
tonic operational mode are declared uncalibrated.
As with incomplete calibration, the menu selec-
tion for the affected mode will flash when the
"SEL" Key is pressed again.