TM 9-6625-1754-14
resistance measurements are made, the
lead and termination resistance should
a. Measurement of an AC Voltage of Unknown
be subtracted from the measurement.
Value.
( 2 ) The ohmmeter in this multimeter (search
(1) Set mode selector switch to the SEARCH
mode) is safe and effective for resistance
MODE.
m e a s u r e m e n t s in circuits with semi-
(2) Select an ac voltage range that gives an
conductors present.
i n d i c a t i o n greater than 1 on the AC
(3) When making resistance measurements
meter scale.
in the search mode, it is not necessary
(3) Estimate the analog reading and set the
to open circuit the test leads to make
digit wheels to the estimated reading.
adjustments. Simply depress the OHMS
(4) S e t the mode selector switch to the
∞ ADJUST control knob as it is rotated
DIGITAL MODE and resolve the meter
and the leads will be open-circuited auto-
pointer to the target line using the digit
matically within the instrument.
wheels, proceeding f r o m left to right.
(4) When making resistance measurements
(5) R e a d the in-line presentation of the
in the digital mode, depress the OHMS
measured value from the digit w-heels
∞ ADJUST control knob for increased
and note decimal point, location. Read
meter sensitivity. The control functions
the units in the window above the digit
like the galvanometers shunt on a wheat-
wheels.
tone bridge.
b. Measurement of a DC Voltage of Unknown
c. Protection System.
Value.
Caution: Normal power lines, because of
(1) Set mode selector switch to the SEARCH
their low impedance nature, are capable under
MODE.
certain conditions of delivering surge currents in
(2) Select a dc voltage range that gives an
excess of the protection specifications of this in-
indication greater than 1 on the meter
strument. Repeated exposure to this type of over-
scale.
load should be avoided as much as possible.
(3) Estimate the analog reading and set the
(1) This multimeter is protected against all
digit wheels to the estimated rending.
damaging overloads within its overload
(4) S e t the mode selector switch to the
protection specification. The protection
DIGITAL MODE and resolve the meter
systems generally provided with conven-
pointer to the target line using the digit
tional multifunction meters protect only
wheels, proceeding from left to right.
m e t e r movements. This multimeter is
(5) R e a d the in-line presentation of the
circuit protected since activation of its
measured value from the digit wheels
resettable protection system open-circuits
and note decimal point location. Read
the test leads for overloads, within the
the units in the window above the digit
specifications, which would be damaging
wheels.
to the meter and precision components.
c. Measurement of an Unknown AC Voltage on
M i l d overloads that drive the meter
an Unknown DC Level.
pointer off-scale in either direction are
(1) First measure the magnitude of the dc
n o t damaging to the meter or circuit
voltage using the, procedure outlined in
components.
paragraph b above.
( 2 ) Before depressing the RESET push-
(2) Choose a suitable coupling capacitor to
button, analyze the circuit to find the
block the dc voltage measured in step (1)
source of overload. This will eliminate
a b o v e and re-connect the multimeter
continued reapplication of the overload
t h r o u g h the capacitor to the voltage
to the instrument by continued use of
source.
the RESET pushbutton.
