Mastech MAS345 Assembly instructions

OPERATOR’S INSTRUCTION MANUAL
•AUTO-RANGE
•DUAL DISPLAY
•CONFORMED IEC1010
DIGITAL MULTIMETER

CONTENTS PAGE
SAFETY INFORMATION ….……………….…………………………………………...
DESCRIPTION …….………….…………………………………………………………
OPERATING INSTRUCTION ..…………………………………………………………
SPECIFICATIONS ………….…...………………………………………………………
ACCESSORIES ………….………………………………………………………………
BATTERY AND FUSE REPLACEMENT ……………...………………………………
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1. SAFETY INFORMATION
The meter has been designed according to IEC-1010 concerning electronic measuring
instruments with an overvoltage category (CAT II) and pollution 2.
Follow all safety and operating instructions to ensure that the meter is used safely and is
kept in good operating condition.
1.1 PRELIMINARY
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When using the meter, the user must observe all normal safety rules concerning :
-Protection against the dangers of electrical current.
-Protection of the meter against misuse.
Full compliance with safety standards can be guaranteed only if used with test
leads supplied. If necessary, they must be replaced with the same model or same
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electric ratings. Measuring leads must be in good condition.
1.2 DURING USE
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·
·
·
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Never exceed the protection limit values indicated in specifications for each range
of measurement.
When the meter is linked to a measurement circuit, do not touch unused terminals.
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 voltage pulses at test points, which -2-

·
·
can damage the meter.
Never perform resistance measurements on live circuits.
Always is careful when working with voltages above 60V dc or 30V ac rms. Keep
fingers behind the probe barriers while measuring.
1.3 SYMBOLS
Important safety information, refer to the operating manual.
Dangerous voltage may be present.
Earth ground.
Double insulation (Protection class II).
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1.4 MAINTENANCE
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·
·
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Before opening the meter, always disconnect test leads from all sources of electric
current.
For continue protection against fire, replace fuse only with the specified voltage
and current ratings:
F 15A/250V
If any faults or abnormalities are observed, the meter can not be used any more
and it has to be checked out.
Never use the meter unless the back cover is in place and fastened fully.
To clean the meter, use a damp cloth and mild detergent only, do not use
abrasives of solvents on it. -4-

2. DESCRIPTION
This meter is an autoranging professional measuring instrument. Digit reading is 3999
counts and the bar graph consists of 38 segments for LCD, capable of performing
functions:
-DC voltage measuring (Auto Ranging)
-AC voltage measuring (Auto Ranging)
-DC current measuring
-AC current measuring
-Temperature measuring
-Resistance measuring (Auto Ranging)
-Capacitance measuring
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-Diode testing
-Transistor testing
-Audible continuity testing
2.1 ON/OFF SWITCH
A push −push switch is used to turn the meter on or off. When the switch is push the
beeper will sound.
2.2 DC/AC OR Ω/ BUTTON
This button is used to select DCV or ACV on voltage range, DCA or ACA on current
range, Ωor on Ω/ range. When the button is push the beeper will sound.
2.3 R-H BUTTON
In auto-range, press this button to select manual range and “R-H” symbol will appear on
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the LCD. Press the button again for more than 1 second will come back the auto-range
mode.
When the R-H button is pushed, voltage ranges will change as:
4V →40V →400V →1000V
Or resistance ranges change as:
40MΩ→4MΩ→400kΩ→40kΩ→4kΩ→400Ω
2.4 B/L BUTTON
Press this button to toggle back-lit ON. The screen of the meter will light. Press the
button again, back-lit turn off.
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2.5 INPUT JACKS
This meter has four input jacks that are protected against overload to the limits. During
use, connect the black test lead to the COM jack and the red test lead as shown below:
FUNCTION RED LEAD CONNECTION INPUT LIMITS
DCV/ACV
Ω
mA
10A
V/Ω
V/Ω
V/Ω
mA
10A
1000V dc or 750V rms ac
250V dc or rms ac
250V dc or rms ac
400mA dc or rms ac
10A dc or rms ac
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2.6 FRONT PANEL
.DISPLAY
.ON/OFF SWITCH
.TRANSISTOR TESTING SOCKET
.FUNCTION SWITCH
.CAPACITANCE OR TEMPERATURE
TESTING SOCKET
.INPUT JACKS
.RS232C SOCKET
.B/L BUTTON
.R-H BUTTON
.DC/AC OR Ω/ BUTTON
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3. OPERATING INSTRUCTION
3.1 VOLTAGE MEASURING
1.
2.
3.
4.
Connect the black test lead to the COM jack and the red test lead to the
V/Ωjack.
Set the function switch at V range and connect test leads across the source or
load under measurement.
Push the DC/AC button to select DCV or ACV measuring mode. (Push the R-H
button to select manual range.)
Read LCD display. The polarity of red test lead connection will be indicated
when making a DC measurement.
3.2 CURRENT MEASURING

1. Connect the black test lead to the COM jack and the red test lead to the mA jack
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for a maximum of 400mA. For a maximum of 10A, move the red lead to the 10A jack.
2.
3.
4.
Set the function switch at mA or 10A range and push the DC/AC button to select
DCA or ACA measuring mode.
Connect test leads in series with the load in which the current is to be
measured.
Read LCD display. The polarity of red test lead connection will be indicated
when making a DC measurement.
3.3 RESISTANCE MEASURING
1.
Connect the black test lead to the COM jack and the red teas lead to the V/Ω jack. (NOTE: The polarity of the red test lead connection is positive “+”)

2.
Set the function switch at Ωrange to be used and connect test leads across the resistance under measurement.
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NOTE:
1.
2.
3.
For resistance above 1MΩ, the meter may take a few seconds to stabilize
reading. This is normal for high resistance measuring.
When the input is not connected, i.e. at open circuit, the figure “OL” will be
displayed and full bar graph appears for the overrange condition.
When checking in-circuit resistance, be sure the circuit under test has all power
removed and all capacitors fully discharged.
3.4 CAPACITANCE MEASURING

1.
2. Set the function switch at nF range. Before inserting capacitor under measurement into capacitance testing socket,
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be sure that the capacitor has been discharged fully.
WARNING:
Before attempting to insert capacitor for testing, always be sure that test leads have
been disconnected from any measurement circuits.
Components should not be connected to the capacitor socket when making voltage
measurements with test leads.
3.5 TEMPERATURE MEASURING
1. Set the function switch at TEMP range.

2. Insert “K” type thermocouple into the temperature measuring socket on front
panel and contact the object to be measured with the thermocouple probe.
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WARNING:
To avoid electric shock, be sure the thermocouple has been removed before changing
to another function measurement. Before attempting to insert thermocouple for testing,
always be sure that test leads have been disconnected from any measurement circuits.
3.6 AUDIBLE CONTINUITY TESTING

1.
2.
3.
Connect the black test lead to the COM jack and the red test lead to the V/Ω
jack. (NOTE: The polarity of red test lead connection is positive “+”)
Set the function switch at position and push the Ω/button.
Connect test leads to two points of the circuit under measurement. If continuity
exists (i.e., the resistance is lower than 30Ω), built-in buzzer will sound.
3.7 DIODE TESTING
1. Connect the black test lead to the COM jack and the red test lead to the V/Ω
jack. -14-
2.
3.
(NOTE: The polarity of the red test lead connection is positive “+” )
Set the function 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.

4. Read LCD display to get the forward voltage drop of the diode under testing.
3.8 TRANSISTOR TESTING
1.
2.
3.
Set the function switch at hFE position.
Determine whether the transistor is NPN or PNP type and locate emitter, base,
and collector lead Insert leads of the transistor into proper holes of the transistor
testing socket on the front panel.
The meter will show the approx. hFE value at test condition of base current
10μA and Vce 3.0V.
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WARNING:
Before attempting to insert transistor for testing, always be sure that test leads have
been disconnected from any measurement circuits.

Components should not be connected to the transistor socket when making voltage
measurements with test leads.
3.9 INTERFACING THE METER WITH A PC (OPTION)
1.
2. Connect the RS232C cable between the meter and computer’s serial ports. Press ON/OFF to turn on the meter. Turn on the computer.
WARNING:
1. Use only the type of serial interface cable RS232C cable exclusively designed
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2. for your meter. Never attempt to modify of extend the length or RS232C cable. Please read this file of readme from Disks.
4. 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 75%.
4.1 GENERAL
Max. Voltage Between Terminals and Earth Ground: 1000V dc or 750V rms ac (sine)
Power Supply: 9V NEDA1604 6F22 006P
Ranging Method: Auto / Manual
Display: LCD, 3999 counts max and bar graph consists of 38 segments
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