TM 5-6640-212-14
Figure 3-5. Analytical Balance, Side View
recessed lamp housing in the left rear of the balance.
that this method cannot be used to zero the knob
Slide the cover from side to side and up and down until
midrange, it is necessary to zero the macro system as
the desired illumination is obtain-ed. Tighten the knurled
described in (6) below.
head screw firmly while holding the cover in position. A
(6) To perform macro zero adjustments, check
replacement bulb is available and is stored in the lower
zero calibration as described in (1) above; then arrest the
spare mount.
beam and remove the hood. Loosen the locking screw
(3) Scale focusing is controlled by the long knurled
or knurled screw as required to zero the macro scale.
knob (1, fig. 3-5) at the rear of the scale. Carefully
Retighten the locking screw, release the beam, and
adjust the knob until the desired focus is achieved on the
check zero again. Repeat the correction if the deviation
optical scale.
exceeds one scale division. As soon as the deviation is
reduced to one scale division, replace the hood and use
(4) Zeropoint adjustment is accomplished by first
the zero control knob to adjust to zero.
rotating the weight control knobs and micrometer drum
(7) Check sensitivity by rotating the weight control
knob until the macro weight scale and optical scale are
knobs until 01 appears on the macro scale while the
returned to zero. Move the arrestment lever into PRE-
beam is arrested. Place a 1-gram weight on the pan,
WEIGH position (fig. 2-22) and adjust the micro scale to
release the beam, and check zero on the optical scales
zero by turning screw (1, fig. 3).
as described in (1) above. Rotate the weight control
(5) Range adjustment of the zero control knob has
knobs to show zero on the macro scale. Let the optical
the effect of recentering the knob. Set the knob in the
scale swing in and read the result. If the full deflection of
center of its adjusting range without regard to micro
0100 is not obtained, adjust the sensitivity by turning the
scale reading.
Arrest the beam by moving the
knurled nut (3, fig. 3-4) to adjust the scale accordingly.
arrestment lever to horizontal position (fig. 2-22).
Turn weight control knob so that 01 appears on the
Remove the balance hood and adjust the knurled knob
macro scale and set zero point as described in (4)
(6, fig. 3-4) until optical and micro scales are zeroed. If
the scale deviation is so great
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