HF scientific DRT-100B Research Turbidimeters - Manual (Page 18)

Page 10 DRT-100B (5/00)
Figure 2
VII. SOURCE LAMP REPLACEMENT & ALIGNMENT
Turn instrument power OFF and disconnect power source. Remove cover from instrument by unscrewing
collar ring on top surface.(Spanner Wrench provided.) Remove the range switch knob (Hex key wrench
provided) and six (6) screws from the sides of the cover. Also remove nut and washer from alarm set
switch. (older models) Remove the four (4) screws that secure heat shield to chassis. Remove heat shield.
The lamp is removed by loosening Screw #1 and removing the electrical leads from TB2 - 5 & 6. Insert new
lamp assembly in place and reconnect electrical leads. The lamp should be positioned so the filament is
perpendicular to the baseplate of the instrument. The new lamp must now be aligned and focused. Insert
lamp alignment tool, HF catalog number 70820, into the Optical Well. Turn instrument on to 1000 NTU
range. Position the lamp so that an image of the filament falls within the rectangular box on the lamp
alignment tool. If necessary, the height of the filament image may be adjusted by loosening Screw #2.
Loosen Screw #3 and move lamp bracket assembly in or out until a narrowly focused image of the
filament is obtained within the rectangular box. Once the filament image has been aligned and focused,
tighten Screws #1, 2, and 3 snugly. Check the focus and alignment to be certain no movement had taken
place during tightening of the screws.
*IMPORTANT - Do not tighten Screw #1 too much as it may crush the base of the lamp.
Replace heat shield. Position the cover in place over the instrument and replace the screws, the
knobs, the rubber gasket, the locking collar, and alarm set switch nut and washer. (older models)
FOCUS LAMP
FOR SHARPEST
VERTICAL
IMAGE OF FILAMENT
CENTERED ON
TARGET
PT. NO.-70820
*NOTE: Dotted line shown represents
lamp filament image.
Lamp shown here from top view.