Quantum ODYSSEY HF Series, Service Manual

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Chapter 4 Theory of Operation
Revision W HF Series X-ray Generators - Service Manual
4-16
Quantum Medical Imaging
Current/Voltage signal is output to HSS Control Board A20A1. In response to
the Over Voltage/Current signal, the HSS Control Board A20A1 monitors the
signal and sends a Fault signal to the generator Logic Board A1, and a "Rotor
Current" error appears on the Operator Control Panel display.
The x-ray Tube Temperature input signal is applied through terminal block
A20A2TB4. The Tube Temperature input is protected with Fuse A20A2F5. If
the voltage on A20A2TB4-1 is above one volt, a Temp error signal is gener-
ated. The TEMP signal is output through connector A20A2J2 to HSS Control
Board A20A1, which then activates a temperature signal to generator Logic
Board A1. In response, a "Rotor Temp" error is indicated on the Operator
Control Panel display.
The following are the ratings of the various fuses located on HSS Drive Board
A20A2:
• F1, F3: AC Input voltage - 15A/500VAC
• F4: Rotor output drive - 15A/500VAC
• F5: Temperature sense input - 0.1A/250V
AEC BOARD CIRCUIT
The automatic exposure control (AEC) option is available in either of two types:
Standard or Universal. The standard type provides for connection of up to two
ion chambers, one for a wall mounted image receptor and one for a table
mounted receptor. Both ion chambers must be of the same type, i.e., either
"slope" or "level". The universal type provides for connection of up to four sepa-
rate ion chambers, each one can be either type (slope or level). The following
paragraphs describe general circuit functions of each AEC type.
Standard Type AEC
The standard type AEC Board A11 (AY40-031S) controls the exposure time to
maintain uniform optical density (O.D.) with respect to various kV and mA
settings. Using AEC, the operator sets the desired kV and mA; the exposure
time is determined by the AEC circuit. AEC calibration is required in order
establish a desired or optimal optical density (refer to Chapter 3, AEC Calibra-
tion).
The AEC Board is designed for use with ion chambers having the following
characteristics:
• Positive slope
• Ion chamber selection signal: active low
• Ion chamber on signal: active low
The AEC Board can control two separate ion chambers; each of the ion cham-
ber connectors is a D-type connector (A11J2 = Wall 1 and A11J5 = Table).
The ion chamber is selected from the operator control console via the TABLE
and WALL receptor keys. These selections are input to control logic con-
tained on Logic Board A1 AY40-006S, which controls the selection of the ion