TB 9-4931-530-50
8. Scale Magnification Accuracy
a. Performance Check
(1) Place a 0.125 inch gage block under both ends of sine plate rolls.
HEAD A control for a 0 (mid-scale) indication on TI meter.
NOTE
0.024 inch is equal to 990 arc seconds.
(3) Replace a 0.125 inch gage block at one end of sine plate roll with 0.149 inch gage
block. If TI meter does not indicate +990 40 (right deflection), perform b below.
(4) Replace 0.149 inch gage block with 0.101 inch gage block. If TI meter does not
indicate -990 40 (left deflection), perform b below.
(5) Set GAGE HEAD selector switch to B and repeat technique of (1) through (4)
above for SENSING HEAD B (fig. 1). If TI meter indications are not within limits, perform
b below.
b. Adjustments
(1) Set GAGE HEAD selector switch to B.
(2) Replace 0.149 or 0.101 inch gage block with 0.125 inch gage block at end of sine
plate roll.
HEAD B (ZERO HEAD A) control for a 0 (mid-scale) indication on TI meter.
(4) Substitute 0.149 and 0.101 inch gage blocks in turn for a 0.125 inch gage block
at the same end of sine plate roll and adjust gain control (recessed in hole in center of range
selector switch) for best compromise or balance of + (right deflection) and - (left deflection)
indications on TI meter.
(5) Repeat (2) through (4) above until no further adjustments are required.
(6) Set GAGE HEAD selector switch to A and repeat technique of (2) through (5)
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