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4.4.2
Precalibration Alignment
* NOTE:
If instrument has not been disturbed and requires only calibration, proceed to 4.4.3 Zero
Adjustment.
1. Remove connecting link at lower end, noting which pivot hole was used. The hole
selected in original manufacture is identified by a scribed circle. See Figure 12.
2. See that upper end of link is attached to yoke arm pivot as originally manufactured. If
position is unknown, refer to Figure 12 and use pivot hole B or G.
When link is on correct side of yoke, (either pivot hole B or G) pen will move in the
required direction on chart. This may be checked by temporarily reconnecting link to
measuring element, applying an input and verify correct pen direction.
3. Center the micrometer screw on pen arm. If equal thread exposure cannot be obtained,
remove screw and start both small and large diameter threads simultaneously. See
Figure 13.
4. Hold pen at the mechanical center of chart. (50% on a uniform chart.) The yoke, Figure
13, should be vertical. If it is not, check for parallel assembly of pen arm to yoke in the
area of the 2 mounting screws. Adjust if necessary.
Precalibration alignment is required only if the recorder has been
disassembled or if a major component has been replaced.
Figure 12. Scribed Pivot Holes
76J Pneumatic Fulscope Recorder
MAINTENANCE
21
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