Philips PW 1720 User Manual

PHILIPS

Table-top X-ray Generator

1720

Instruction manual

3. OPERATION

This paragraph describes the method of operating the PW 1720 and the options, such as timers etc., but does not include operating instructions for accessory devices such as cameras and vertical goniometers.

The initial installation of the PW 1720 is described in the Service part of the manual.

3-1

3.1.

INITIAL CHECKS

Before switching on the generator, check the following:

Check that HT tank transport fixing screw is removed, see Service installation section.

Cooling water for the X-ray tube is turned on.

The tube shield is fixed in the required position

The X-ray tube installed is suitable for the analysis program.

The kV and mA controls are in minimum position (10 kV and 5

The PW 1161 X-RAYS ON lamp (if fitted) is correctly wired, and is placed in a conspicuous position.

The timers (if required) are installed.

The accessory units, required for the analysis program, are correctly fitted to the tube shield.

The white push-button must be depressed by the accessory, and the shutter disc is rotated to allow the X-ray beam to pass.

Set the filter disc to the desired position.

Check that the a.c. mains stabiliser is correctly installed, when required.

3.2. SAMPLE ANALYSIS

The procedure for analysis will depend on the accessories being used, and the operation of these devices is described separately in the respective manuals. They should be made ready for analysis by loading the sample, film (etc.), or positioning the goniometer or other device -see also paragraph 3.4.

l Momentarily operate the GENERATOR I push-button, and when the safety circuit is complete the X-RAYS

ON lamp(s) will light to show that X-rays are being generated. The lamp in the push-button is also lit.

Increase the kV control to the required value, then adjust the mA control until the desired X-ray tube

current is indicated by the meter. Do not exceed the rated maximum power to the X-ray tube, i.e. the setting of

shown in the “X-ray diffraction tubes” leaflet (9499 300 10311) are not applicable.

(0°, 45°,

90°).

mA),

also refer to paragraph 3.6.

and mA must not exceed the values shown for X-ray tubes in Appendix 1. The ratings

Determine the exposure time, and set the timer if fitted - also refer to paragraph 3.3.

l Place the SHUTTERS three - position switch to select the desired window shutter (with timer), or

infinite time (middle position).

l Open the shutter by simultaneously pressing the lowest SHUTTERS push-button, and the SHUTTERS I

push-button corresponding to the window shutter which is to be opened, refer to figure 3.1. The shutter will remain open until the timer exposure time has elapsed, or until the SHUTTERS 0 push-button is

operated (when a timer is not fitted or used). During the time that the shutter is opened, the X-ray beam is allowed into the camera or goniometer, the red lamps on the tube shield below the shutter/filter disc are lit, and the red flags will appear in the side holes of the cover over the tube shield mechanism In the event of a failure of one of the lamp bulbs in the tube shield, the shutter is closed immediately.

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

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.

3.3.

Fig. 3.1. Opening

the

window shutter.

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.

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