OEC 9800C-Arm, Service Manual, Page: 142 / 490

kV Generation
Circuit/Mechanical Descriptions
The kV generation and control for the system is accomplished on four PCB cards and the High Voltage Tank. The kV value is
sensed in the tank and fed back to the HV Regulator PCB to modify and stabilize the drive to the section. The battery bank
supplies the high current needed by the tank to generate the high voltage for the X-ray tube anode. The reservoir capacitors
allow the high ripple current generated by the switching of the IGBTs to bypass the battery.
The microprocessor on the X-Ray Controller PCB triggers kV generation on commands received from the Control Panel
Processor and Fluoro Functions PCB via ARCNET. The X-ray Controller PCB supplies an analog voltage to the HV Regulator
PCB to control the kV voltage required. The XRAY_ENABLE signal allows X-rays to be generated and the XRAY_ON signal
switches a control signal through circuitry on the HV Regulator PCB to adjust the kVP waveform rise time. These two signals are
generated when the X-ray button or the hand switch or foot switch buttons are depressed to make X-rays.
The output of the HV Regulator PCB is combined with output of a sense circuit from the High Voltage Tank. The signals, equal
amplitude and opposite polarity, are used by the HV Regulator PCB to regulate the output of the Generator Driver PCB to the
Insulated Gate Bipolar Transistors (IGBTs) on the Snubber PCB.
The B+ from battery packs is applied to the bus all the time after precharging is completed. IGBTs Q1 and Q2 drive the HV Tank step-up transformer
through the series tuned circuit formed by L1, C1 and C2.
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Service Periodic Maintenance Contents Schematics Illustrated Parts Installation