mA Generation
Circuit/Mechanical Descriptions
mA generation and regulation is accomplished with four printed circuit cards, with feedback from the High Voltage Tank. Prior to
X-ray generation, the initial technique is setup, i.e., filament, select, kV, and mA. The correct filament selection is output to a
relay on the Filament Driver PCB, and the correct FILAMENT SUPPLY voltage set up. Filament drive is provided from the X-Ray
Controller PCB to the optocouplers on the Generator Driver PCB. The optocouplers isolate the filament drive signals and in turn,
drive to the Filament Driver PCB through a coupling transformer. The transformer output drives a pair of MOSFETs that drive the
selected filament transformer in the high voltage tank.
The amplitude of the filament drive is regulated on the Filament Drive PCB by changing the output stage supply voltage
FIL_B_PLUS. The measured mA is compared with the commanded mA in the X-ray Controller to generate the FIL_ERROR
signal. The FIL_B_CNTL signal is set up by the X-Ray Controller to make the Filament Driver PCB supply voltage 160V for the
small filament and 140V for the large filament. . FIL_B_SEN is compared with the FIL_B_CNTL and FIL_ERROR voltages to
adjust FIL_REG_BASE so that the FIL_B_PLUS varies ±5V to control the mA. This circuitry is split between the Generator Driver
and Filament Driver PCBs.
2
Service
Periodic Maintenance
Contents
Schematics
Illustrated Parts
Installation
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