InnoVet Select
™
HF APR
Service Manual
57
9.1.1 Using the Required Test Equipment
The installer is responsible for achieving waveforms which are both of the proper
amplitude and of the proper “square” waveshape, where the desired amplitude is achieved
and maintained throughout the entire exposure.
A Machlett Dynalyzer (or equivalent high voltage divider) and a storage oscilloscope
are required for calibration.
The Dynalyzer will indicate total kVp and mA, while the
scope allows a view of the waveform shape. It is preferable for the scope to be dual
trace, 100 MHz response. Some hand-held scope/meters have a frequency response and
pixel resolution that do not give a reliable and discernible view of the output waveforms.
Using a dual trace storage oscilloscope, connect to the Dynalyzer kV and mA
output. Set the scope to trigger from the kV waveform.
If no Dynalyzer is available
an alternate method is to use a mAs meter between the mA
jumpers on the HV transformer, a kVp meter in the x-ray beam, and a scope on the kV/mA
test points on the 01003-000System Controller board. The meters and scope will give the
proper total output, and the scope the proper waveshape.
Connect the scope to the kV and mA test points on the 01003-000System Controller
board. Set the scope to trigger from the kV waveform.
TP8 is the kVp feedback test point.
One volt is equal to 33.3 kVp.
TP9 is the mA test point. One volt is equal to 100 mA.
TP2 is ground
.
The test points are located in the upper left hand corner of the 01003-000System
Controller pcb, which is on the front of the hinged door in the Power Module. Make
exposures, monitoring and adjusting the leading edge and stabilized levels of mA and kVp
until satisfactory outputs have been achieved across the operating range.
A mAs meter can be put between the red and black terminals behind the cathode
receptacle.
Be certain to remove the jumper when using the mAs meter and replace
the jumper when removing the meter at end of calibration.
NOTE: While it is possible to calibrate this generator without a Dynalyzer, is it
absolutely essential that an oscilloscope be used for calibration. Because the
leading edge and stabilized levels of kV and mA are independently controlled, the
shape of the waveforms must be verified and adjusted to proper levels during
installation. Using a kV meter and mAs meter alone will not allow the installer to
calibrate the unit properly, with component damage a possible result.