Steren MUL-300 User manual

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Before using your new Professional Multimeter, please read
this instruction manual to prevent any damage. Put them
away in a safe place for future references.
SECURITY INFORMATION
This multimeter has been designed according to IEC-1010
specifications for electronic testing equipment.
When using your multimeter, observe the following safety rules:
Protection against damages caused by electrical current.
Protection against damages caused by inadequate use.
The testing points meet all safety standards, if you need to
replace these make sure the new testing points have the
same characteristics or are the same model points.
Never exceed the indicated limits in each measuring range.
When the multimeter forms a bridge with the circuit that is to
be measured, don’t touch the points that are being used to
measure.
When you don’t know the range of the equipment to be
measured, set the dial to the highest range possible.
Before adjusting the dial to a different range or a different
function, disconnect the testing points from the multimeter.
When you break the power circuits, remember that the
voltage amplitude pulses can be higher than normal, and
this pulses can damage the meter.
Never measure resistance, capacity, inductance, diode, or
continuity on live circuits.
Whenever measuring voltages above 60 VDC or 30 VAC
rms, place your fingers above the protection rings on the
testing points.
Do not store or use this meter in places exposed to direct
sun light, high temperatures, humidity or condensation.
MAINTENANCE
1.- Before opening your multimeter, always disconnect the
testing points from the multimeter’s source of electrical current.
2.- For an effective protection against fire, always replace a fuse
with one that has the same characteristics in voltage and current:
15A / 250V.
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Before usin
g
y
our new Professional Multimeter, please read
t
his instruction manual to prevent an
y
dama
g
e. Put them
a
wa
y
in a safe place for future references
.

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3.- If you notice any kind of malfunction or abnormality, stop all
use of your multimeter until it is checked by authorized
personnel.
4.- Never use your multimeter if the protective cover is not
properly placed.
5.- Clean your multimeter periodically with a clean humid rag and
soft detergent. Never use solvents or abrasives in order to clean
your multimeter.
6.- If the multimeter is going to be stored without use for an
extended period of time, remove the batteries in order to prevent
damage to your multimeter.
DESCRIPTION
This multimeter is a professional instrument.
3 ½ digit LCD screen, 28 mm tall, with polarity indicator and
readings up to 1999 counts.
DC voltage measurements
AC voltage measurements
DC Amps measurement
AC Amps measurement
Temperature measurement
Resistance measurement
Capacity measurement
Diodes measurement
Audible continuity test
On / Off button
Light button (5 seconds length)
Hold button
RANGE FUNCTION AND SELECTOR
This multimeter is a professional, portable instrument, with a
large LCD screen for an easy reading. It has special
characteristic, in order to avoid a bad connection of the testing
points. The input female jacks (red colour) are made specially
for functions and ranges. Using a mechanic block system, it will
allow us to choose the right position of the testing points.
If the testing points are plugged and you turn the dial, you
cannot perform the operation until you remove the red testing
point. Then first, remove the point and then set the dial in the
required range, after that, replace the testing point in the
available connector (the others are blocked)
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The dial allow us to choose the range and the function to be
measured.
GENERAL SPECIFICATIONS
PRECISION
This unit is specified for a one year period in 64ºF to 82 º F
temperatures and 75% relative humidity.
Operation temperature: 32ºF to 104ºF
Input: 9V (alkaline or carbon zinc battery) (1x9V)
Maximum voltage between connectors and ground:
1000VDC or VAC (peak value).
Includes 30 ranges for all scales.
Protection against over range, for all ranges.
LCD screen, 1999 counts, 3 1/2 digits, 28mm tall
Over range indicator: “1” or “-1”
Polarity indicator: “ – “
Low battery indicator
Approximate time for sample request: 0,4seconds
Temperature factor: < 0,1 x accuracy/ ºC
Operation altitude: 7000ft maximum
Dimensions: 191 x 82 x 36 mm
Weight : 380g including battery and case
DC VOLTAGE
10Mohms input impedance, in all ranges
Protection against over range:
in 200mV range: 250VDC or VAC rms
In 2 to 1000V range: 1000VDC or 700VAC rms
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Ran
g
e Resolution Accurac
y
200mV 0,1mV ±0,5 % of rgd ± 1d
2V 1mV ±0,5 % of rgd ± 3d
20V 10mV ±0,5 % of rgd ± 3d
200V 100mV ±0,5 % of rgd ± 3d
1000V 1V ±0,8 % of rgd ± 3d

In the smallest voltage range, the meter may display an
unstable reading, specially when the testing leads have
not reached the circuit , this is normal because of the high
sensitivity of the meter. When the testing points touched the
circuit, you will get a true reading.
AC VOLTAGE
10Mohms input impedance, in all ranges
Protection against over range:
in 200mV range: 250VDC or VAC rms
in 2 to 1000V range: 1000VDC or 700VAC rms
Response: Average response, calibrated in sine wave rms
Frequency: 40 to 400Hz
Test in 60/50Hz
In the smallest voltage range, the meter will show an
unstable reading, specially when the testing leads have
not reached the circuit , this is normal because of the high
sensitivity of the meter. When the testing points touched the
circuit, you will get a true reading.
DC AMPS
Protection against over charge:
In 2mA to 200mA range: F1: 200mA / 250V fuse
in 10A range: F2: 10A / 250V
Maximum current input: mA connector: 200m
10A connector: 10A
Voltage loss: 200mV
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Ran
g
e Resolution Accurac
y
2V 1mV ±1,0 % of rgd ± 5d
20V 10mV ±1,0 % of rgd ± 5d
200V 100mV ±1,0 % of rgd ± 5d
1000V 1V ±1,2 % of rgd ± 5d
Ran
g
e Resolution Accurac
y
2mA 1A ±1,0 % of rgd ± 3d
20mA 10A ±1,0 % of rgd ± 3d
200mA 100A ±1,5 % of rgd ± 5d
10A 10mA ±2,0 % of rgd ± 10d
I
n t
h
e sma
ll
est vo
l
ta
g
e ran
g
e, t
h
e meter ma
y
di
sp
l
a
y
an
u
nstable readin
g
, speciall
y
when the testin
g
leads have
not reached the circuit , this is normal because of the hi
g
h
s
ensitivit
y
of the meter. When the testin
g
points touched the
c
ircuit,
y
ou will
g
et a true readin
g.
I
n t
h
e sma
ll
est vo
l
ta
g
e ran
g
e, t
h
e meter w
ill
s
h
ow an
u
nstable readin
g
, speciall
y
when the testin
g
leads have
not reached the circuit , this is normal because of the hi
g
h
s
ensitivit
y
of the meter. When the testin
g
points touched the
c
ircuit,
y
ou will
g
et a true readin
g.

AC AMPS
Protection against over charge:
in 2mA to 200mA range: F1: 200mA / 250V fuse
In 10A / 250V range
Maximum current input: mA connector:200mA
10A connector : 10A
Voltage loss : 200mV
Frequency: 40 to 400Hz
Test in 60 / 50Hz
Response: Average response, calibrated in sine wave rms
RESISTANCE (ohms)
Maximum voltage in an open circuit:
in 20Mohm range: 3,0V
Other ranges: <700mV
Protection against over charge: 250VDC or VCA rms in all
ranges
CAPACITANCE
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Ran
g
e Resolution Accurac
y
2mA 1A ±1,2 % of rgd ± 5d
200mA 0,1mA ±2,0 % of rgd ± 5d
10A 10mA ±3,0 % of rgd ± 10d
Ran
g
e Resolution Accurac
y
200Ohms 0,1Ohms ±1,0 % of rgd ± 10d
2000ohms 1Ohm ±1,0 % of rgd ± 1d
20kOhms 10Ohms ±1,0 % of rgd ± 1d
200kOhms 100Ohms ±1,0 % of rgd ± 1d
2Mohms 1kOhm ±1,0 % of rgd ± 1d
20Mohms 10kOhms ±1,0 % of rgd ± 5d
Ran
g
e Resolution Accurac
y
2nF 1pF ±4,0 % of rgd ± 3d
20nF 10pF ±4,0 % of rgd ± 3d
200nF 0,1pF ±4,0 % of rgd ± 3d
2F 1nF ±4,0 % of rgd ± 3d
20F 10nF ±4,0 % of rgd ± 3d

TEMPERATURE
Protection against over charge: 250VDC or VAC rms
AUDIBLE CONTINUITY TEST
Protection against over charge: 250VDC or VAC rms
Voltage in an open circuit: 2,8V approx.
TESTING DIODES
Protection against over charge: 250VDC or VAC rms
Approximate ADC in direct polarization: 1mA
Approximate VDC in inverted polarization; 2,8V
FREQUENCY
Protection against over charge: 250VDC o VAC rms
Sensitivity: 200mV rms and <10Vrms input
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Ran
g
e Resolution Accurac
y
-20ºC a 0ºC 1°C ±5,0 % of rgd ± 5d
0°C to 400°C 1°C ±1,0 % of rgd ± 3d
401°C to 1000°C 1°C ±2,0 % of rgd ± 3d
Function Description
The buzzer sounds if the resistence is under 70 ohm
Function Resolution
1mV Approximate reading of the diode voltage
in direct polarization
Description
Ran
g
e Resolution Accurac
y
20kHz 10Hz ±1,5 % of rgd ± 10d
)))

INSTRUCTIONS
HOLD BUTTON
If you need to maintain a value in the screen, press the button
marked with an H, then the current value will be displayed in the
screen, until you press the button H, once again.
LIGHT BUTTON
Press this button if you want to turn the backlight on, specially
when you do measures at nite. Press the button with the icon of
a sun and the backlight will turn on for 5 seconds (this light con-
sume many energy, just use it in special conditions).
If the battery voltage is under 7 volts, in the screen will display a
battery icon, but if you use the backlight at the same time, after
it turn off, the battery icon may disappear, because the voltage
down.
MEASUREMENT METHODS
MEASURING DC / AC VOLTAGE
1.- Connect the red testing point to the jack signaled “V ” and
the black testing point to the jack signaled “COM”.
2.- Set the dial to the VDC / VAC setting
3.- Connect the testing points to the equipment to be measured.
4.- Turn the equipment to be measured on, the voltage will ap-
pear on the LCD screen. The polarity will also appear.
MEASURING DC / AC AMPS
1.- Connect the red testing point to the jack signaled “mA” when
measuring up to 200 mA, and to the jack signaled “A” when
measuring above, and the black testing point to the jack signaled
“COM”.
2.- Set the dial to the VDC or VAC setting .
3.- Open the circuit to be measured and connect the testing
points (serial) where the current must be measured.
4.- Read the current value in the screen.
For resistance over 1Mohm, the meter can be delayed for
few seconds, this is normal because of the high value of the
resistance.
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For resistance over 1Mohm, the meter can be dela
y
ed for
f
ew seconds, this is normal because of the hi
g
h value of the
resistance
.

When the input is not connected, the “1” will be displayed in
the screen, indicating overcharge.
Remember to fully discharge the energy from the capacitors
and the circuit, when you measure resistance inside of a
circuit.
MEASURING CAPACITY
1.- Connect the red testing point to the jack signaled “V ” and
the black testing point to the jack signaled “COM”.
2.- Set the dial to the “nF” or “F” range.
3.- Before inserting the capacitor in the capacitor jack, make sure
that it has been completely discharged and make sure to respect
polarity.
4.- Read the value in the screen.
In the smallest range of capacity, the reading will includes a
small value for testing points influence. But this won’t affect
the accuracy of the reading.
For higher capacity, the meter will take more time to
stabilize the reading.
MEASURING TEMPERATURE
1.- Set the dial to TEMP range.
2.- Connect the thermo pair type K into the meter (same
connector for ”V“ and ”COM“), then use the tip to touch the
object to be measured.
3.- Read the value in the screen.
TESTING AUDIBLE CONTINUITY
1.- Connect the red testing point to the jack signaled “V ” and
the black testing point to the jack signaled “COM”.
2.- Set the dial to ))) range, and the button in ))) position.
3. Connect the testing points to the circuit to be measured. If the
resistance is under 70Ohms, the buzzer will sound.
MEASURING DIODES
1.- Connect the red testing point to the jack signaled “V ” and
the black testing point to the jack signaled “COM”.
2.- Set the dial to range.
3.- Connect the red testing point to the diode to be measured
and the black testing point to the cathode.
4.- The voltage will appear on the LCD screen in m Volts.
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W
hen the input is not connected, the “1” will be displa
y
ed in
t
he screen, indicatin
g
overchar
g
e
.
Remember to full
y
dischar
g
e the ener
gy
from the capacitors
a
nd the circuit, when
y
ou measure resistance inside of a
c
ircuit
.
I
n the smallest ran
g
e of capacit
y
, the readin
g
will includes a
s
mall value for testin
g
points influence. But this won’t affect
t
he accurac
y
of the readin
g.
For hi
g
her capacit
y
, the meter will take more time to
s
ta
bili
ze t
h
e rea
di
n
g.

MEASURING FREQUENCY
1.- Connect the red testing point to the jack signaled “V ” and
the black testing point to the jack signaled “COM”.
2.- Set the dial to 20kHz range.
3.- Connect the testing points to the circuit to be measured.
4.- The frequency will appear on the LCD screen.
Measures over 10V rms are allowed, but the accuracy is not
guaranteed.
WARNING
Before removing the cover from your multimeter, make sure the
testing points are disconnected to avoid the risk of electrical
shock.
REPLACING THE BATTERY AND THE FUSE
The fuse rarely needs to be replaced and when it does, it is usu-
ally due to an error in operation.
If “BAT” appears on your LCD screen, the battery needs to be
replaced.
To replace the fuse ( F1: 200 mA / 250 V y F2: 10 A / 250 V ) or
the battery remove the cover from the multimeter removing the
three screws on the back of the multimeter. Replace the fuse
and/or battery and replace the cover on your multimeter.
HOLDER
Place the holder up to three different positions, in order to obtain
an easy LCD reading.
ACCESSORIES
User’s manual
Testing points
Battery
Thermo pair type K
Case
The characteristics for this multimeter are subject to change
without notice.
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M
easures over 10V rms are allowed, but the accurac
y
is not
g
uarantee
d.
T
he characteristics for this multimeter are sub
j
ect to chan
ge
w
ithout notice
.