Mastech MAS838 Assembly instructions

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OPERATOR’S
INSTRUCTION MANUAL
DIGITAL MULTIMETER

SAFETY INFORMATION
This multimeter has been designed according to IEC −1010
concerning electronic measuring instruments with an
overvoltage category (CATⅡ) and pollution 2.
Follow all safety and operating instructions to ensure that the
meter is used safely and is kept in good operating condition.
Full compliance with safety standards can be guaranteed only
with test leads supplied. If necessary, they must be replaced
with the type specified in this manual.
SAFETY SYMBOLS
Important safety information, refer to the operating
manual.
Dangerous voltage may be present.
Earth ground.
Double insulation (Protection class II).
Fuse must be replaced with rating specified in the
manual.
MAINTENANCE
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Before opening the case, always disconnect test leads
from all energized circuits.
For continue protection against fire; replace fuse only
with the specified voltage and current ratings:
F 200mA/250V(Quick Acting)
Never use the meter unless the back cover is in place
and fastened completely.
Do not use abrasives or solvents on the meter. To clean
it using a damp cloth and mild detergent only.
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DURING USE
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Never exceed the protection limit values indicated in
specifications for each range of measurement.
When the meter is linked to measurement circuit, do not
touch unused terminals.
Never use the meter to measure voltages that might
exceed 600V above earth ground in category Ⅱ
installations.
When the value scale to be measured is unknown
beforehand, set the range selector at the highest
position.
Before rotating the range selector to change functions,
disconnect test leads from the circuit under test.
When carrying out measurements on TV or switching
power circuits always remember that there may be high
amplitude voltages pulses at test points, which can
damage the meter.
Always is careful when working with voltages above 60V
dc or 30V ac rms. Keep fingers behind the probe barriers
while measuring.
Before attempting to insert transistors for testing, always
be sure that test leads have been disconnected from any
measurement circuits.
Components should not be connected to the
hFE socket when making voltage measurements with
test leads.
Never perform resistance measurements on live circuits.
GENERAL DESCRIPTION
The meter is a handheld 31/2 digital multimeter for measuring
DC and AC voltage, DC current, Resistance, Diode, Transistor,
Temperature and Continuity Test with battery operated.

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FRONT PANEL

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FRONT PANEL DESCRIPTION
c
d
e
f
g
h
Display
3 1/2 digit, 7 segment, 15mm high LCD.
Rotary switch
This switch is used to select functions and desired
ranges as well as to turn on/off the meter.
Hold button
When this button is pushed, the display will keep the last
reading and “ ”symbol will appear on the LCD until
pushing it again.
“10A” jack
Plug in connector for red test lead for 10A measurement.
“COM” jack
Plug in connector for black (negative) test lead or plug in
the black plug with “k” type thermocouple.
“VΩmA” jack
Plug in connector for red (positive) test lead for voltage,
resistance and current (except 10A) measurements or
plug in the red plug with “k” type thermocouple.
SPECIFICATIONS
Accuracy is specified for a period of one year after calibration
and at 18 to 28℃(64°F to 82°F) with relative humidity to 80%.
GENERAL
Maximum voltage between
terminals and earth ground :CATⅡ600V
Fuse protection :F 200mA/250V
Power :9V battery, NEDA 1604 or 6F22
Display : LCD, 1999 counts, updates 2-3/
sec.
Measuring method :Dual-slope integration A/D
converter
Overrange Indication :Only figure “1” on the display
Polarity indication :“-”displayed for negative polarity
Operating Environment :0 to 40℃
Storage temperature :-10℃to 50℃.

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Low battery indication :“ ”appears on the display
Size :138mm×69mm×31mm
Weight : Approx.170g.
DC VOLTAGE
Range Resolution Accuracy
200mV 100μV ±0.5% of rdg ±2 digits
2V 1mV ±0.5% of rdg ±2 digits
20V 10mV ±0.5% of rdg ±2 digits
200V 100mV ±0.5% of rdg ±2 digits
600V 1V ±0.8% of rdg ±2 digits
Overload Protection: 250V rms. For 200mV range and 600V dc
or rms. ac for other ranges.
DC CURRENT
Range Resolution Accuracy
2mA 1μA ±1% of rdg ±2 digits
20mA 10μA ±1% of rdg ±2 digits
200mA 100μA ±1.5% of rdg ±2 digits
10A 10mA ±3% of rdg ±2 digits
Overload Protection: F 200mA/250V fuse. (10A range unfused)
AC VOLTAGE
Range Resolution Accuracy
200V 100mV ±1.2 % of rdg ±10 digits
600V 1V ±1.2 % of rdg ±10 digits
Overload Protection: 600V dc or rms. ac for all ranges.
Frequency range: 40Hz to 400Hz.
Response: Average responding, calibrated in rms. of a sine
wave.
DIODE & CONTINUITY
Range Description
If continuity exists (about less than 1.5kΩ), built-in
buzzer will sound.
Show the approx. forward voltage drop of the diode.
Overload Protection:250V dc or rms. ac.

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TRANSISTOR hFE TEST (0-1000)
Range Test Range Test Current Test Voltage
NPN & PNP 0-1000 Ib=10μA Vce=3V
RESISTANCE
Range Resolution Accuracy
200Ω0.1Ω±0.8% of rdg ±3 digits
2kΩ1Ω±0.8% of rdg ±2 digits
20kΩ10Ω±0.8% of rdg ±2 digits
200kΩ100Ω±0.8% of rdg ±2 digits
2MΩ1kΩ±1.0% of rdg ±2 digits
Maximum Open Circuit Voltage: 3.2V
Overload Protection:250V dc or rms. ac for all ranges.
TEMPERATURE
Range Resolution Test Range Accuracy
℃ 1℃-20℃to 0℃ -0℃to 400℃
400℃to 1000℃
±10% of rdg ±2digits
±1.0% of rdg ±3digits
±2.0% of rdg
TEMPERATURE
Range Resolution Test Range Accuracy
°F 1 °F -4°F to 32°F 32°F to 752°F
752°F to 1832°F
±10% of rdg ±2digits
±1.0% of rdg ±3digits
±2.0% of rdg
OPERATING INSTRUCTIONS
DC VOLTAGE MEASUREMENT
1.
2.
3.
4.
Connect the red test lead to the “V.Ω.mA” jack and the
black lead to the “COM” jack.
Set rotary switch at desired DCV position. If the voltage
to be measured is not known beforehand, set range
switch at the highest range position and then reduce it
until satisfactory resolution is obtained.
Connect test leads across the source or load being
measured.
Read voltage value on the LCD display along with the
polarity of the red lead connection.

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DC CURRENT MEASUREMENT
1.
2.
3.
4.
Connect the red test lead to the “V.Ω.mA” jack and the
black test lead to “COM” jack. (For measurements
between 200mA and 10A, remove red lead to“10A”
jack.)
Set the rotary switch at desired DCA position.
Open the circuit in which the current is to be measured,
and connect test leads in series with the circuit.
Read current value on LCD display along with the
polarity of red lead connection.
AC VOLTAGE MEASUREMENT
1.
2.
3.
4.
Connect the red test lead to “V.Ω. mA” jack and the
black test lead to the “COM” jack.
Set the rotary switch at desired ACV position.
Connect test leads across the source or load being
measured.
Read voltage value on the LCD display.
DIODE TEST
1.
2.
3.
Connect the red test lead to “V.Ω.mA” jack and the black
test lead to the “COM” jack (The polarity of red lead is
positive “+”.).
Set the rotary switch at “ ” position.
Connect the red test lead to the anode of the diode to be
tested and the black test lead to the cathode of the
diode.
The approx. forward voltage drop of the diode will be
displayed. If the connection is reversed，only figure “1”
will be shown.
TRANSISTOR TEST
1.
2.
3.
Set the rotary switch at “hFE” position.
Determine whether the transistor under testing is NPN or
PNP and locate the emitter，base and collector leads.
Insert the leads into proper holes of the hFE socket on
the front panel.
Read the approximate hFE value at the test condition of
base current 10μA and Vce 3V.

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RESISTANCE MEASUREMENT
1.
2.
3.
4.
Connect the red test lead to “V. Ω. mA” jack and black
test lead to the “COM” jack. (The polarity of red lead is
positive “+”.)
Set the rotary switch at desired ”Ω” range position.
Connect test leads across the resistor to be measured
and read LCD display.
If the resistance being measured is connected to a
circuit，turn off power and discharge all capacitors before
applying test probes.
AUDIBLE CONTINUITY TEST
1.
2.
3.
Connect red test lead to “V.Ω.mA”, black test lead to
“COM”.
Set range switch to “ ” position.
Connect test leads to two points of circuit to be tested. If
continuity exists, built-in buzzer will sound.
MEASURING TEMPERATURE
1.
2.
3.
If the meter is the ℃function, set the rotary switch at
℃. Position. If it is the °F function, set the rotary switch
at °F Position. The LCD display will show the current
environment temperature.
Connect the red lead of“K ”type thermocouple into
the “V.Ω.mA” jack and the black lead of“K ”type
thermocouple into the “COM” jack.
Read temperature value on the LCD display.
WARNING:
To avoid electric shock, be sure the thermocouple has been
removed before changing to another function measurement.
BATTERY & FUSE REPLACEMENT
If “ ”appears on display, it indicates that the battery should
be replaced.
Fuse rarely need replacement and blow almost always as a
result of operator’s error.
To replace battery &fuse (200mA/250V) remove the 2 screws

in the bottom of the case. Simply remove the old, and replace
with a new one. Be careful to observe battery polarity.
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WARNING
Before attempting to open the case, always be sure that test
leads have been disconnected from measurement circuits.
Close case and tighten screws completely before using the
meter to avoid electrical shock hazard.
ACCESSORIES
•Operator’s instruction manual
•Set of test leads
•Gift box
•9 volt battery. NEDA 1604 6F22 type
•“K”type thermocouple
•Holster (option)

HYS004610 A1