VOLT-OHM MILLIAMPERE METER (VOM)
or
MULTI-TESTER
Prepared by:
Mr. TC ABUSTAN
VOLT-OHM-MILLIAMPERE METER (VOM )
A VERSATILE ELECTRICAL AND ELECTRONIC
INSTRUMENT USED TO MEASURE VOLTAGE, CURRENT,
AND RESISTANCE.
PANEL
MIRROR SCALE
TEST PIN
POINTER
TEST LEADS or
ZERO POSITION PROBE
ADJUSTER
ZERO OHM
RANGE ADJUSTER
SELECTOR
KNOB TEST LEAD
STORAGE
The parts of the VOM is built to
accurately detect and display an
electrical quantity in a form readable
by a human being.
THE SCALE AND POINTER
POINTER
SCALE
Used to align the
pointer right to the
zero position
ZERO
POSITION
ADJUSTER
Aknob for selecting the proper
range for the quantity to be
measured.
RANGE
SELECTOR
KNOB
Used to connect the instrument to
the circuit or devices
to be measured.
TEST
PIN
TEST
LEADS or
PROBE
TEST LEAD
STORAGE
Used to align the
pointer right zero
the zero position
on the ohm
scale.
ZERO OHM
ADJUSTER
NOTE:
When reading, be sure that you are perpendicular to the
VOM to avoid parallax error.
NO SHADOW
MIRROR
POINTER
Used in measuring resistance ( Ohms )
METER RANGE READINGMULTIPLIER
X1 1
X 10 10
X I00 I00
X 1K 1K
X100K 100K
Ω
Ω
RESISTANCE MEASURING
PROCEDURE:
Set to a certain resistance range
Short the two probe and adjust zero
ohm adj. knob to zero ohm resistance.
Do this in all range setting before the
start of resistance measurement.
Start measuring, look the scale and
resistance range.
NOTE: Never touch the probe tips because our
body have a resistance
MEASUREMENT:
USE
APPROPRIATE
RANGE SETTING
POINTER MUST
BE NEAR CENTER
NOTE:
NEVER USED OHMMETER
TO A CIRCUIT WITH A
SUPPLY VOLTAGE
EX. RANGE X 1 = 10 X 1 RANGE X 10 = 10 X 10
= 10 Ohms = 100 Ohms
B C
A D
B
A C
D
Give the resistance measurement of different pointer and range
setting.
A. Range X 1 = ________ Ω B. Range X10 = ______ Ω
C. Range X1K = ________ Ω D. Range X10K = ______ Ω
AC VOLTS DC VOLTS
RANGE RANGE
1000 1000
250 250
50 50
10 2.5
Ω
0.5
Ω
0.1
VOLTAGE MEASUREMENT
1. Pull out the
leads from the _
+
store space.
VOLTAGE MEASUREMENT
2. Place the
function switch in DCV 1000 1000 ACV
the appropriate
position (Volts
and AC or DC)
NOTE: Select the
highest range if the DCmA Ω
voltage to be measured
is unknown.
3. Connect the test
leads parallel to
the component you
are measuring.
4. Switch down the
ranges, one range at a time,
until you reach the lowest
unusable range, (with the
pointer still on the scale).
DCV or ACV AC10V
VOLTAGE SCALE
A B
C
A
B
Give the voltage measurement of different pointer and range setting
A. Range 10 = _________ ACV Range 250 = _________ DCV
B. Range 1000 = _________ ACV Range 50 = _________ DCV
C. Range 50 = _________ ACV Range 0.5 = _________ DCV
