8.
MULTIMETER MAINTENANCE.
a. Multimeter TS-352 B/U (fig 15) is a multirange AC and DC volt-ohm-
milliammeter using a single moving coil, 50-microampere meter of the D'Arsonval
type, with appropriate scales marked to indicate AC and DC volts, DC current, and
resistance in ohms. The voltmeter circuit is essentially a meter with series
multiplier resistors. The multiplier resistors are the same for AC and DC
measurements. However, since the meter is a DC milliammeter, the AC voltage input
must be rectified before being applied to the meter.. Wafer switches are used in
the switching circuits to control the functions and ranges of the multimeter. All
meter shunt resistors and some multiplier resistors are selected by the positioning
of the contacts in the switching circuits. The switching circuits also connect the
battery, or batteries, and appropriate shunt and series resistors into the
necessary circuit arrangements for resistance measurements in the different
ohmmeter ranges.
b. The daily and weekly maintenance duties assigned to the operator are
detailed in figure 16. Organizational preventive maintenance responsibilities are
detailed in figure 17. No special tools or test equipment other than those issued
with the equipment are required by the operators or organizational maintenance
personnel to accomplish their duties.
c. When troubleshooting this equipment organizational maintenance personnel
perform all functions of the multimeter operation. They proceed with the functions
until an abnormal condition or result is observed. Noting the abnormal condition
or result they refer to the troubleshooting chart (fig 18) and perform the checks
and corrective actions indicated. When the corrective measures indicated do not
result in correction of the trouble, a higher maintenance category repair is
required.
9.
LOW VOLTAGE CIRCUIT TESTER MAINTENANCE.
a. The LVCT test set (fig 19) is a self-contained, portable instrument,
used for checking and analyzing low voltage direct current electrical circuits.
The test set has four independent sections: voltmeter circuit, field rheostat
circuit, 1/4-ohm load resistor circuit, and ammeter load bank circuit. Necessary
test leads and a separate external shunt assembly come with the set and should be
stowed in the compartment provided when not in use. Pertinent publications are
stowed in a bracket provided in the cover.
b. Before and after-operation preventive maintenance services for the low
voltage test set are listed in figure 20. Operators should note minor defects
discovered during operation of the unit so that correction can be made as soon as
possible. Some deficiencies require that operations be ceased to avoid equipment
damage; therefore, all operators must be highly trained. Operators of the low
voltage circuit tester have a limited troubleshooting responsibility. When a-
malfunction occurs immediate steps should be taken to locate and correct the
problem. Figure 21 details the operator's troubleshooting responsibility.
c. Organizational maintenance is provided repair parts, common tools, and
equipment necessary for replacement of those parts most likely to become worn,
broken, or otherwise unserviceable. Weekly, monthly, and quarterly preventive
maintenance responsibilities are listed in figure 22. Close adherence to the
organizational maintenance troubleshooting procedures (fig 23) materially reduces
the time required to locate the cause of malfunctions and restore the equipment to
a serviceable condition.
OS 010, 8-P19
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