Philips PW 1720 - Manual (Page 3)

3-2
When the shutter is closed the generator will switch off, unless another shutter is still open in one of the
other tube shield positions. Alternatively. the generator can be switched off manually by operating the
GENERATOR 0 push-button. All lamps will extinguish. Before the generator is switched off the power
to the X-ray tube should be reduced, by first turning the mA control to minimum, and then the kV control.
Any generation of HT will be inhibited if the shutter does not fully close after a close shutter command.
Fig. 3.1. Opening the window shutter.
3.3. SHUTTER CONTROL
For camera work it is usual to control the exposure time of the film to X-rays by using a PW 1722 timer. Two
timers can be fitted: the left-hand timer will control the shutter of either window 1 or window 2, and the
other timer the shutter of window 3 or 4. This paragraph describes the automatic and manual control of the
shutter operation.
When the camera is installed on its bracket in front of the required exit window of the tube shield, open the
shutter disc and push the camera forward until the collimator enters the hole in the disc. Ensure that the
microswitch button on the tube shield is actuated by the pin or arm of the camera.
NOTE: The space between the front of the collimator and the exit opening of the tube shield should be kept
as small as possible to ensure that radiation does not escape. Take care that the filter disc is free
to move, and is not damaged.