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S T A R T I N G   A N D   T E S T I N G

Page 16

also serve to make contact for the lamp circuit. The bracket can be removed by simply pulling it sideways. Four adjustments for the exciting lamp are provided on this bracket, namely:

Clamping Adjustment

The lamp base is held in a socket which is clamped by means of a thumbscrew. At the bottom of the socket is a spring contact stud. The lamp base has a pin in the side, and the socket is slotted to clear this pin. When putting in a lamp, see that the clamp screw is loosened, then push the lamp down until the pin is out of the slot, and turn It so that the pin locks it in place, like a bayonet joint. The lamp must always have the filament perpendicular to the length of the lens tube, that is, parallel with the film. Except when putting in a new lamp, this adjustment should not need attention.

Vertical Adjustment

Loosen the clamping screw of this adjustment, then by means of the adjusting screw move the lamp bracket up or down as required until the light is vertically centered on the slit in the lens tube. Tighten clamping screw.

Sideways Adjustment

Loosen the clamping screw of this adjustment, then by means of the adjusting screw move the lamp bracket sideways so as to center the light on the slit horizontally. When trying to move bracket away from you, press steadily on the clamping screw at the same time; otherwise the bracket will not move. Finally tighten clamping screw.

Focusing Adjustment

Loosen the clamping screw of this adjustment, then turn the adjusting screw so as to get the sharpest possible focus of the light on the slit. Tighten clamping screw.

The filament image should now be bright and sharp and perfectly centered on the slit. Check the illumination in front of the aperture plate by means of the white card test. If the light spot shows any shadows at top or bottom or sides, move the lamp slightly up or down or sideways, as required, until these shadows disappear. Do not change the focus.

After an exciting lamp has been used considerably, the filament may show a tendency to sag. This has a bad effect on the volume, as the filament image no longer coincides with the slit. Another result of ageing that tends to cut down the volume is blackening of the lamp bulb, which reduces the amount of light emitted. Therefore, as soon as the filament begins to sag noticeably or the glass begins to darken, replace the lamp.

On account of the number of operations involved in adjusting the exciting lamp, and the possibility that one may have to be replaced during a show, it is very necessary to have some means of putting in a new lamp and operating it at a moment's notice. This can be done by setting up in the machine each spare lamp and bracket supplied, and making all bracket adjustments needed for proper operation.
As already explained, the bracket can be slipped bodily off the supporting parts without disturbing any adjustmerits; the spare lamp and bracket can therefore be removed and stored away ready for immediate use. If possible, keep the lamp in the bracket; otherwise, mark each lamp so to permit quick identification. Lubrication of Mechanism

The mechanism should be lubricated regularly in the manner that will now be specified. Avoid lubricating at irregular intervals and avoid using more lubricant