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4-1
4. MEASUREMENTS AND ADJUSTMENTS
Checking the angle setting
The angle setting can be checked with the glass-disc
method which is explained below.
41 459 At2
Put glass disc 4822 395 90204 on the turntable.
Make sure that the glass disc beds down well on the
turntable.
Place the CD mechanism under a light source, under
which there is a straight line (e.g. under a fluorescent
tube with grid).
Set the arm to mid-position of its radial track.
Turn the mechanism until the arm is parallel to the line
under the light source (see figure below).
Look into the direction and in the extension of the line to
the reflection there of on the glass disc and in the
objective.
Locate the CDM in such a way that the line reflected by
the glass disc runs across the centre of the objective.
The line reflected by the objective should fall just within
the surface of the objective. If this is the case, the two
lines are not more than 4 mm apart and squareness is
correct.
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Lee
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OBJECTIVE
41 460 Al2
Fig. 5
Turn the CD mechanism through 90° relative to the
previous position. The arm must be kept in mid-position
(see figure above).
Repeat the previous check.
CS 9 488 cs
DISC (TRANSPARENT)
Adjusting the angle setting
For adjusting the angle settig one or both of the two
locking knocks for the bearing plate on pos. 59 must be
broken.
If a check on the angle setting shows that the angle
falls outside the tolerance, the angle should NOT be
adjusted for minimum deviation, but it should be
adjusted within the tolerance.
The new setting should lie between the old setting and
the optimum setting. After adjusting the setting, the
friction of the arm must be checked. This is done by
means of a spring pressure gauge which is held against
the magnet of the focusing unit.
The friction of the arm, measured over the entire meter
reading, should not be greater than 25 mN.
When the friction appears to be too high, the RAFOC unit
must be replaced and the angle between disc and light
path adjusted.
The lock is adjusted as follows:
SS
ws F
41 458 Al2
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Fig. 6
Loosen screws C (see figure above) unitl bearing plate D
can be displaced. Correct the angle setting by moving
the bearing plate into the direction shown in figure below.
Tighten screws C, ensuring that the setting does not drift.
Then double check the setting in two directions.
OBJECTIVE =)
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ADJUST SCREWS
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CD
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> 5
Fig. 7
38 692 A12
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