GE Healthcare Senographe DS
Revision 1 Service Information and Procedures Class A 2385072-16-8EN
Job Card CAL A001 - Heater Current Scale Factor
Page no. 1649 Chapter 9
JC-CAL-A-001.fm
Job Card CAL A001 - Heater Current Scale Factor Chapter 9
1SUPPLIES
None
2TOOLS
• Multimeter (Fluke 87) or a multimeter that can operate in true RMS AC ammeter mode
(e.g.: Fluke 8060).
• HV unit/cable adaptor
!
Notice:
IMPORTANT NOTE: To ensure accurate measurement:
• For ALL Digital Multimeters: The Autorange function MUST NOT be used, as it can lead to severe
measurement errors (>40%).
• For ALL Digital Multimeters: The Relative Measurement function MUST NOT be used to reset to zero
the natural offset displayed when there is no current measured. The offset is automatically reset to
zero by the principle of the rms measurement.
• Measurement configurations to be used are as follows:
- Fluke 87: no shunt, in the 10 A AC range.
- Fluke 8060: used with 20 A shunt in the 200 mV AC range (shunt reference: 80J10).
3 REQUIRED EFFORT
Personnel: 1 Field Engineer
Time: 67 minutes
4 SAFETY PRECAUTIONS
CAUTION
In case of equipment breakdown or service engineer error during this calibration proce-
dure, the resulting parameter values might become so unreasonable as to render the X-ray
tube filament supply circuit unusable. This can show up as an error message during
power up, and thus inhibit use of the calibration software. If this happens, the only way to
cancel the error is to manually re-enter the default parameter values (see section 6 for
default parameter values), and then switch the Senographe off and back on again before
again attempting a calibration.
5 PREREQUISITES
None
6 CALIBRATION OF HEATER CURRENT SCALE FACTOR
The objective is to determine the scale factor K and fixed offset VOF between the X-ray tube filament
current command from the software and the real filament current value obtained. Each tube track has its
own filament supply circuit, so this calibration procedure is to be performed for each of the two tracks.
DEFAULT PARAMETER VALUES ARE K = +9.450E+0 (9.45) AND VOF = +0.000E+0 (0.0).
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