Model 4 12A Section V
SECTION V
MAINTENANCE
5-1. INTRODUCTION. 5-10. VOLTMETER ACCURACY CHECK.
5-2. This section contains information necessary to a. A dc voltage standard and a variable line
maintain the kp- Model 412A/AR. The following transformer are required for this chcck. If an -tip-
paragraphs describe the Performance Checks, Calibration
Model 738BR Voltmeter Calibrator is used, it
Procedures, Troubleshooting, and Servicing Procedures. should be allowed a 30-minute warm-up period.
5-3. REQUIRED TEST EQUIPMENT.
b. Connect 412A to variable line transformer, and set
line voltage switch (1 15/230) to correspond to line
54. Recommended test equipment for maintaining and voltage being used. Turn 412A ON and allow
checking performance of the Model 412A is listed in Table
5-1. Test instruments other than those recommended may 5-minute warm-up period.
be used if their specifications equal or exceed the required c. Set 412A FUNCTION to VOLTS, POLARITY to
characteristics.
+.
55. PERFORMANCE CHECKS.
d. Connect VOLTS and COM leads to dc standard
5-6. Use the following procedures to verify proper out put.
operation of the Model 412A. The 412A and test
equipment should be operated at 115/230 Vac unless e. Check 412A indication against dc standard output
otherwise specified. A Performance Test Card is provided at at full scale on each 412A range. Maximum error
the end of this section for recording the performance of the should be no greater than f 1% of full scale (one
Model 412A. The card may be removed from the manual small division on top scale).
and used as a permanent record of the incoming inspection
or of a routine performance check. If the Model 412A does NOTE
not meet specifications at any point in this procedure, refer
to Paragraph 5-1 5, Adjustment and Calibration procedure. When checking the Modcl 412A on
the .001 and .003 volt ranges, turn
5-7. METER ZERO.
off the dc standard output and note
any 412A zero offset due to
5-8. The meter pointer should rest over the zero thermoelectric voltage. Add or
calibration mark when the instrument is at normal subtract as necessary any offset from
operating temperature, is turned off, and is in the normal
the 412A reading.
operating position. If the pointer is off zero, perform the
mechanical adjustment procedure outlined in Paragraph f. Check 412A meter tracking on the 1 V rang at all
5-1 8 before proceeding with the performance checks.
cardinal points on the meter scale. Maximum crror
should be no greater than 0.01 V with cithcr
5-9. Turn the Model 412A POWER switch ON. After a polarity input. .
5-minute warm-up period, the meter pointer should rest on
zero when the input leads are shorted. If not, perform the
g. Repeat step e on 1 V range at line voltages of 103
electrical zero adjustment outlined in Paragraph 5-22. and I27 volts (or 207 and 253 V).
NOTE
5-11. MILLIAMMETER ACCURACY CHECK.
Operating the Model 412A/AR without
grounding the third (power line ground) a. A dc voltage standard and the prccision rcsistors
wire of the power cable will result in a listed in Table 5-2 rcquircd for this chcck.
zero offset of the meter and oscillation of
the printer. b. Set 4 12A FUNCTION to MA. I?OLARITY to +.
001 29-5 5-1 |
ACEC
