Manual

Model 475

3.1 CALIBRATION PROCEDURE

Equipment Required:

Precision resistance decade box: resolution, .01 ohm; accuracy, + .02%.

Precision milliamp source: resolution, 1 uA; accuracy + .01% (+ 2uA).

Potentiometer adjusting tool.

Figure 3-1. Potentiometer Adjustment/Testpoint Locations

R53

R52

R33

R27

R10

R24

R19

R17

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Model 475 3.1 CALIBRATION PROCEDURE Equipment Required: Precision resistance decade box: resolution, .01 ohm; accuracy, + .02%. Precision milliamp source: resolution, 1 uA; accuracy + .01% (+ 2uA). Potentiometer adjusting tool. R24 R2 R53 R52 R5 R10 R7 R33 R17 R19 R27 Figure 3-1.
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3.1.1 Disassembly a. Remove battery from instrument (refer to 2.4.1). b. Remove bottom case half from printed circuit board assemblies by extracting three screws from case bottom and one screw holding wrist strap lug. c. Remove top case half from printed circuit board assemblies by extracting screw on clad side of Analog board between output controls. d. Re-connect battery to connector. 3.2.1 a. b. c. d. e. f. g. h. i. j. k. l. m. n. o. p. q. r. s. t. u. v. w. x. y. z. aa. bb. cc. dd. ee. ff.
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gg. hh. Adjust R53 for a display reading of 390.0 ohms. Repeat steps 3.1.2.z through 3.1.2.gg until no further adjustments are required for correct display readings. 3.1.2 mA Input Calibration a. Observing proper polarity, connect precision mA source to mA input jacks of instrument. b. Set instrument to calibrate/mA input mode. c. Adjust mA source output to 32.00 mA. d. The display should read 32.00 mA. If not, adjust R10 for correct reading. e. Adjust mA source output to 3.2 mA. f.