CEM DT-912 User manual

OPERATING INSTRUTION
DIGITAL MULTIMETER
10A COM V mA
OFF
600
200
2000
20m
200
m
10A
1.5V
9V
200
2000
20k
200k
2000
k
600
200
20
2000
m
200
m
V AC
A DC
BATT.
CAT III 600V
V DC
HOLD

1

2
SAFETY INSTRUCTIONS
This meter has been designed for safe use, but must be
operated with caution. The rules listed below must be
carefully followed for safe operation.
1. NEVER apply voltage or current to the meter that
exceeds the specified maximum:
Input Limits
Function
Maximum Input
VAC
600V DC/AC
V DC or V
AC
600V DC/AC, 200Vrms on 200mV
range
mA DC
200mA 250V fast acting fuse
A DC 10A 250V fast acting fuse
(30 seconds max every 15 minutes)
Resistance
, Continuity
250Vrms for 15sec max
2. USE EXTREME CAUTION when working with high
voltages.
3. DO NOT measure voltage if the voltage on the "COM"
input jack exceeds 500V above earth ground.
4. NEVER connect the meter leads across a voltage source
while the function switch is in the current, resistance, or
diode mode. Doing so can damage the meter.
5. ALWAYS discharge filter capacitors in power supplies

3
and disconnect the power when making resistance or
diode tests.
6. ALWAYS turn off the power and disconnect the test
leads before opening the doors to replace the fuse or
batteries.
7. NEVER operate the meter unless the back cover and the
battery and fuse doors are in place and fastened
securely.
SAFETY SYMBOLS
This symbol adjacent to another symbol,
terminal or operating device indicates that
the operator must refer to an explanation in
the Operating Instructions to avoid
personal injury or damage to the meter.
This WARNING symbol indicates a
potentially hazardous situation, which if not
avoided, could result in death or serious
injury.
This CAUTION symbol indicates a
potentially hazardous situation, which if not
avoided, may result damage to the
product.
This symbol advises the user that the
terminal(s) so marked must not be
MAX
WARNING
CAUTION

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connected to a circuit point at which the
voltage with respect to earth ground
exceeds (in this case) 500 VAC or VDC.
This symbol adjacent to one or more
terminals identifies them as being
associated with ranges that may, in normal
use, be subjected to particularly hazardous
voltages. For maximum safety, the meter
and its test leads should not be handled
when these terminals are energized.
This symbol indicates that a device is
protected throughout by double insulation
or reinforced insulation.
CONTROLS AND JACKS
10A COM V mA
OFF
600
200
2000
20m
200
m
10A
1.5V
9V
200
2000
20k
200k
2000
k
600
200
20
2000
m
200
m
V AC
A DC
BATT.
CAT III 600V
V
DC
HOLD
1
6
2
3
7
5
4

5
1. LCD Display
2. Function switch
3. 10A jack
4. COM jack
5. Positive jack
6. Data Hold Button
7. Backlight Button
Note: Tilt stand, fuse and battery compartment are on rear
of unit.
SYMBOLS AND ANNUNCIATORS
•))) Continuity
Diode test
µ micro (amps)
m milli ( volts, amps)
k kilo (ohms)
 Ωohms
VDC volts direct current
VAC volts alternating current
ADC amps direct current
BAT Battery test

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SPECIFICATIONS
Function
Range
Resolution
Accuracy
DC Voltage
(V DC)
200mV
0.1mV
±(0.5% reading + 2
digits)
2000mV
1mV
20V
0.01V
200V
0.1V
±(0.8% reading + 2
digits)
600V
1V
AC Voltage
(V AC)
200V
0.1V
±(1.2% reading + 10
digits
(50/60Hz)
600V
1V
DC Current
(A DC)
2000µA
1µA
±(1.0% reading + 2
digits)
20mA
10µA
200mA
100µA
±(1.2% reading + 2
digits)
10A 10mA ±(2.0% reading + 2
digits)
Resistance
200Ω
0.1Ω
±(0.8% reading + 2
digits)
2000Ω
1Ω
20kΩ
0.01kΩ
200kΩ
0.1kΩ
2000kΩ
1kΩ
±(1.0% reading + 2
digits)
Battery Test
9V
10mV
±(1.0% reading + 2
digits)
1.5V
1mV
NOTE: Accuracy specifications consist of two elements:
•(% reading) – This is the accuracy of the measurement
circuit.

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•(+ digits) – This is the accuracy of the analog to digital
converter.
NOTE: Accuracy is stated at 65oF to 83oF (18oC to 28oC) and
less than 75% RH.
SPECIFICATIONS
Diode Test Test current of 1mA maximum,
open circuit voltage 2.8V DC
typical
Continuity Check Audible signal will sound if the
resistance is less than
approximately 30Ω
Battery Test current 9V (6mA); 1.5V (100mA)
Input Impedance >1MΩ
ACV Bandwidth 45Hz to 450Hz
DCA voltage drop 200mV
Display 3 ½ digit, 2000 count LCD, 1.1”
digits
Overrange indication “1” is displayed
Polarity Automatic (no indication for
positive polarity); Minus (-) sign
for negative polarity.
Measurement Rate 2 times per second, nominal
Low Battery Indication “BAT” is displayed if battery
voltage drops below operating
voltage
Battery one 9 volt (NEDA 1604) battery

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Fuses mA, µA ranges; 0.2A/250V fast
blow
A range; 10A/250V fast blow
Operating Temperature 32oF to 122oF (0oC to 50oC)
Storage Temperature -4oF to 140oF (-20oC to 60oC)
Relative Humidity <70% operating, <80% storage
Operating Altitude 7000ft. (2000) meters maximum.
Weight 255g
Size 150mm x 70mm x 48mm
Safety For indoor use and in accordance
with Overvoltage Category II,
Pollution Degree 2. Category II
includes local level, appliance,
portable equipment, etc., with
transient overvoltages less than
Overvoltage Category III.
BATTERY INSTALLATION
WARNING: To avoid electric shock, disconnect the test
leads from any source of voltage before removing the
battery door.
1. Disconnect the test leads from the meter.
2. Open the battery door by loosening the screw using a
Phillips head screwdriver.
3. Insert the battery into battery holder, observing the correct
polarity.
4. Put the battery door back in place. Secure with the screw.

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WARNING: To avoid electric shock, do not operate the
meter until the battery door is in place and fastened
securely.
NOTE: If your meter does not work properly, check the fuses
and batteries to make sure that they are still good and that
they are properly inserted.
OPERATING INSTRUCTIONS
DATA HOLD BUTTON
The Data Hold function allows the meter to "freeze" a
measurement for later reference.
1. Press the DATA HOLD button to “freeze” the reading on
the indicator. The indicator “HOLD” will be appear in the
display.
2. Press the DATA HOLD button to return to normal
operation.
BACK LIGHT BUTTON
1. The BACK LIGHT button is used to turn the back light on
or off. Press the BACK LIGHT BUTTON to turn the back
light on.
2. Press the BACK LIGHT BUTTON to turn the back light
off.
WARNING: Risk of electrocution. High-voltage
circuits, both AC and DC, are very dangerous and
should be measured with great care.

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1. ALWAYS turn the function switch to the OFF position when
the meter is not in use.
2.If “OL” appears in the display during a measurement, the
value exceeds the range you have selected. Change to a
higher range.
NOTE: On some low AC and DC voltage ranges, with the test
leads not connected to a device, the display may show a
random, changing reading. This is normal and is caused by
the high-input sensitivity. The reading will stabilize and give a
proper measurement when connected to a circuit.
DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the
circuit is being switched ON or OFF. Large voltage surges
may occur that can damage the meter.
1. Set the function switch to the highest V DC position.
2. Insert the black test lead banana plug
into the negative (COM) jack.
Insert the red test lead banana plug
into the positive (V) jack.
3. Touch the black test probe tip to the
negative side of the circuit.
Touch the red test probe tip to the
positive side of the circuit.
4. Read the voltage in the display. Reset the function
switch to successively lower V DC positions to obtain

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a higher resolution reading. The display will indicate
the proper decimal point and value. If the polarity is
reversed, the display will show (-) minus before the
value.
AC VOLTAGE MEASUREMENTS
WARNING: Risk of Electrocution. The probe tips may not
be long enough to contact the live parts inside some 240V
outlets for appliances because the contacts are recessed
deep in the outlets. As a result, the reading may show 0
volts when the outlet actually has voltage on it. Make sure
the probe tips are touching the metal contacts inside the
outlet before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the
circuit is being switched ON or OFF. Large voltage surges
may occur that can damage the meter.
1. Set the function switch to the highest V AC position.
2. Insert the black test lead banana
plug into the negative (COM) jack.
Insert red test lead banana plug into
the positive (V) jack.
3. Touch the black test probe tip to the
negative side of the circuit.
Touch the red test probe tip to the
positive side of the circuit.

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4. Read the voltage in the display. Reset the function
switch to successively lower V AC positions to obtain
a higher resolution reading. The display will indicate
the proper decimal point and value.
DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the
10A scale for longer than 30 seconds. Exceeding 30
seconds may cause damage to the meter and/or the test
leads.
1. Insert the black test lead banana
plug into the negative (COM) jack.
2. For current measurements up to
200mA DC, set the function switch
to the highest DC mA position and
insert the red test lead banana plug
into the (mA) jack.
3. For current measurements up to
10A DC, set the function switch to
the 10A range and insert the red test lead banana plug
into the (10A) jack.
4. Remove power from the circuit under test, then open up
the circuit at the point where you wish to measure
current.

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5. Touch the black test probe tip to the negative side of the
circuit.
Touch the red test probe tip to the positive side of the
circuit.
6. Apply power to the circuit.
7. Read the current in the display. For mA DC
measurements, reset the function switch to successively
lower mA DC positions to obtain a higher resolution
reading. The display will indicate the proper decimal
point and value.
RESISTANCE MEASUREMENTS
WARNING: To avoid electric shock, disconnect power to
the unit under test and discharge all capacitors before
taking any resistance measurements. Remove the
batteries and unplug the line cords.
1. Set the function switch to the highest Ω position.
2. Insert the black test lead banana plug
into the negative (COM) jack
Insert the red test lead banana plug
into the positive Ω jack.
3. Touch the test probe tips across the
circuit or part under test. It is best to
disconnect one side of the part under
test so the rest of the circuit will not interfere with the
Ohms

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resistance reading.
4. Read the resistance in the display and then set the
function switch to the lowest Ω position that is greater
than the actual or any anticipated resistance. The display
will indicate the proper decimal point and value.
CONTINUITY CHECK
WARNING: To avoid electric shock, never measure
continuity on circuits or wires that have voltage on them.
1. Set the function switch to the position.
2. Insert the black lead banana plug into the negative
(COM) jack
Insert the red test lead banana plug into the positive (Ω)
jack.
3. Touch the test probe tips to the circuit or wire you wish to
check.
4. If the resistance is less than approximately 30, the
audible signal will sound. If the circuit is open, the display
will indicate “1”.
DIODE TEST
1. Insert the black test lead banana plug into the
negative COM jack and the red test lead banana
plug into the positive diode jack.

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2. Turn the rotary switch to the /•))) position.
3. Touch the test probes to the diode under test.
Forward voltage will indicate 400 to 700mV.
Reverse voltage will indicate “I”. Shorted devices
will indicate near 0mV. Shorted devices will
indicate near 0mV and an open device will indicate
“I” in both polarities.
BATTERY TEST
1. Insert the black test lead banana plug into the
negative COM jack and the red test lead banana
plug into the positive Vjack.
2. Select the 1.5V or 9V BAT position using the
function select switch.
3. Connect the red test lead to the positive side of the
1.5V or 9V battery and the black test lead to the
negative side of the 1.5V or 9V battery.
4. Read the voltage in the display.
Good
Weak
Bad
9V battery:
>8.2V
7.2 to 8.2V
<7.2V
1.5V battery:
>1.35V
1.22 to 1.35V
<1.22V

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REPLACING THE BATTERIES
WARNING: To avoid electric shock, disconnect the test
leads from any source of voltage before removing the
battery door.
1. When the batteries become exhausted or drop below the
operating voltage, “BAT” will appear in the right-hand
side of the LCD display. The batteries should be
replaced.
2. Follow instructions for installing batteries. See the
Battery Installation section of this manual.
3. Dispose of the old batteries properly.
WARNING: To avoid electric shock, do not operate your
meter until the battery door is in place and fastened
securely.
REPLACING THE FUSES
WARNING: To avoid electric shock, disconnect the test
leads from any source of voltage before removing the fuse
door.
1. Disconnect the test leads from the meter and any item
under test.
2. Open the fuse door by loosening the screw on the
door using a Phillips head screwdriver.
3. Remove the old fuse from its holder by gently pulling it

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out.
4. Install the new fuse into the holder.
5. Always use a fuse of the proper size and value
(0.2A/250V fast blow for the 200mA range, 10A/250V
fast blow for the 10A range).
6. Put the fuse door back in place. Insert the screw and
tighten it securely.
WARNING: To avoid electric shock, do not operate your
meter until the fuse door is in place and fastened securely.