Mastech MS8238A User manual

MS8238A
User's Manual
Digital Multimeter
600V
CAT II
MS8238A
250

CONTENTS
2.Safety Information..................................1
2.1 Safety Standards................................1
1.Overview .................................................1
2.2 Precautions......................................2
Warning
1.Overview
To avoid electrical shock or personal injury,
please read all safety information, warnings and
precautions before using the meter.
The MS8238A is a small, safe and reliable 3 1/2 digit
handheld multimeter. This meter can measure AC/DC
voltage, AC/DC current, resistance, diode, continuity,
battery test and non-contact voltage tests. This tool is
ideal for professionals and hobbyists alike.
2. Safety Information
2.1 Safety Standards
The MS8238A meets the safety standards UL61010-1,
CSA C22.2 No.61010-1, CAT II 600V and a pollution
degree 2.
• The protection provided by the meter can only be
ensured if all safety procedures are strictly followed.
• The safety symbols on the meter are to advise of
potential dangerous situations.Caution is required
when measuring close to the mete’s safety limits.
• Never exceed the protection limit values indicated in
the specifications for each range of measurement.
2.3 Electrical Symbols ..............................3
3.Description and Usage ...........................4
3.1 Front Panel.......................................4
3.2 Display ...........................................5
3.3 Using the Meter..................................6
4.Specifications ......................................10
4.1 General Specifications........................10
4.2 Technical Specifications ......................11
5.Maintenance.........................................14
5.1 General Maintenance .........................14
5.2 Replacing the Battery and Fuses.............15
5.3 Replacing the Probe ...........................15
01
WARNING
The special attention should be paid when using the meter
because the improper usage may cause electric shock and
damage the meter .The safety measures in common safety
regulations and operating instruction should be complied with
when using. In order to make fully use of its functions and
ensure safe operations please comply with the usage in this
section carefully. If the equipment is used in a manner not
specified by the manufacturer, the protection provided by the
equipment may be impaired.
6. Accessories.....................................................15

02
03
2.2 Precautions
• To avoid electrical shock or personal injury, observe
and follow all safety precautions
• Check the meter for damage before use. Do not use if
any damage is observed.
• Check the test leads for cracks or exposed wires before
using the meter. Replace if necessary.
• Ensure the meter works properly by testing a known
voltage source first.If not working properly, the
protective equipment may be damaged; have the meter
serviced before using.
• Never measure voltages that may exceed the protection
limit indicated on the meter.
• Always be careful when working with voltages above
60V dc or 30V ac rms. Keep fingers behind the probe
barriers when making voltage measurements.
• Make sure the test leads are in the correct input jacks
before measurement.
• Do not expose the meter to explosive gas, dust or vapor.
• When connecting the test leads to a measurement
circuit, connect the common lead first, then the live lead.
Reverse when disconnecting.
• Turn off power to circuit and discharge all capacitors
before making resistance, continuity or diode
measurements.
• In order to avoid incorrect DC voltage readings, check
the circuit for AC voltage first, then put the meter in the
appropriate DC voltage range.
• Turn off circuit power and check fused before connect
the leads when measuring current.Turn circuit power
on after making connection.
• Never use the meter unless the back cover is in place
and fastened securely.
• When the low battery indicator“ ”is displayed, replace
the battery.The accuracy of the meter cannot be
guaranteed while the low battery indicator is on.
• Before opening the case, always disconnect test leads
from all energized circuits.
• For continued protection against fire, replace fuse only
with the specified voltage and current ratings listed in
the manual.
2.3 Electrical Symbols
Important safety information. Read the manual.
High voltage with danger.
Ground.
Double Insulation (Class II safety equipment).
Fuse must be replaced as per the specification herein.
Accord with the related EU laws and regulations
AC (Alternating Current)
DC (Direct Current)
Conforms to UL STD 61010-1;
Certified to CSA STD C22.2 NO.61010-1
This product has been tested to the requirements
of CAN/CSA C22.2 NO.61010-1,second edition,
including Amendment 1.
CAT II (Measurement category ll): it is for measurements
performed on circuits directly connected to the low voltage
installation.

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05
3 Description and Usage
3.1 Front Panel
1.LCD display
2.Data hold button
3.Rotary switch
4.10A input jack
5.Common jack
6.Input jack (all functions except current greater than
200mA)
7.Non-contact voltage (NCV) button
8.Non-contact voltage (NCV) indicator
8
1
2
7
3
4
5
6
3.2 Display
1.Low battery indicator
2.Data hold
3.Measurement display
4.Polarity indicator
5.Diode cycle
2
3
1
4
MS8238A
250
5

06
07
3.3 Using the Meter
3.3.1 Data Hold
The data hold function will hold the current reading on
the display.
• Press the “HOLD” button to hold the current reading.
“H” symbol will appear on the display.
• Press the “HOLD” button to release the hold.
Hold the “NCV” button down in any mode and the meter
will activate the non-contact voltage detection.
• Hold the meter up to a voltage source and the buzzer
will sound and the NCV indicator will light up if voltage
is detected.
• Release the “NCV” button to stop NCV detection.
3.3.2 Non-Contact Voltage Detection (NCV)
3.3.3 AC/DC voltage measurement
• Set the rotary switch to the appropriate AC or DC
voltage range.
• Connect the red test lead to the input jack and the black
lead to the COM jack.
• Connect the leads to the circuit under test and read the
measurement on the display. Observe polarity for DC
measurements. If “OL” is display, it means the
measurement has exceeded the current range. Move
the rotary switch to a higher range.
Warning
Do not measure voltages higher than 600V DC
or AC rms to perevent damage to the meter or
personal injury.
3.3.4 AC/DC current measurement
• Turn off power to the circuit. Allow all capacitors to
discharge.
• Set the rotary switch to the appropriate AC or DC
current range.
• Depending on the current to be measured, connect the
red test lead to either the input or 10A jack and the black
lead to the COM jack.
• Break the circuit and connect the leads in series with the
circuit (black lead on the lower voltage side).
• Turn circuit power on and read the measurement on the
display. If “OL” is display, it means the measurement
has exceeded the current range.Move the rotary switch
to a higher range.
Warning
Never measure open-circuit voltages exceeding
250V between the input terminals and ground to
prevent injury or damage to the meter.
NOTE
Check fuses before making current measurements,
Make sure to use correct input jacks to prevent
damage to the meter.

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4. Specifications
4.1 General Specifications
When battery voltage drops below
normal operating voltage,“ ”is
shown on the display
Polarity Indication Display automatically displays “-“
Power Source 1x 9V battery (NEDA 1604, 6F22 or 006P)
Function Range
Safety Rating CAT II 600V; pollution degree: 2
Operating Altitude ≤2000m
Operating Temperature/
Humidity 0~40°C, <80% RH
Storage Temperature/
Humidity -10~60°C, <70% RH, remove battery
Max. Input between
terminals and earth
ground
600V DC or AC rms
Fuse Protection 10A ranges: F1:F10A H 250V
mA range: F2:F250mA H 250V
Sample Rate Approx. 3 times/sec.
Display 3 ½ digit LCD display
Overload Indication Display shows “OL”
Low Battery Indication
4.2 Technical Specifications
Accuracy: ±(% of reading + digits) at 18°C~28°C with a
relative humidity of <80%; guaranteed for a period of one year.
4.2.3 Resistance
Resolution Accuracy
200Ω
2kΩ
0.1kΩ
0.001kΩ
0.1Ω
0.01kΩ
0.001MΩ
20kΩ
200kΩ
2MΩ
Measuring range
±(0.8% of reading +4 digits)
Overload protection: 250V DC or AC (RMS)
Resolution Accuracy
200V
600V 1V
0.1V
4.2.2 AC Voltage
Max. input voltage: 600V DC or AC rms.
Frequency Response: 40~400Hz, sine wave rms
(avg. response)
Measuring range
±(1.0% of reading +5 digits)
4.2.1 DC Voltage
Max. input voltage: 600V DC or AC rms.
Resolution Accuracy
200mV
2V
0.1V
0.001V
0.1mV
0.01V
1V
20V
200V
600V ±(0.8% of reading +5 digits)
Measuring range
±(0.5% of reading +2 digits)

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09
3.3.5 Resistance measurement
• Turn off power to the circuit. Allow all capacitors to
discharge.
• Set the rotary switch to the appropriate resistance range.
• Connect the red test lead to the input jack and the black
lead to the COM jack.
• Connect the leads to the circuit under test and read the
measurement on the display.
Tips for measuring resistance:
• In-circuit resistance is usually different from a resistors
rating due to the fact that the meter’s test current flows
in parallel with the circuit.
• For increased accuracy when measuring low
resistances, short the test leads, record the value
displayed, then connect the leads to the circuit and
subtract the shorted value from the circuit measurement.
• When the leads are disconnected from the circuit under
test, “OL” will be displayed on the screen.
Warning
To prevent injury or damage to the meter,turn
off power to circuit and discharge all capacitiors
fully before making resistance measurements.
3.3.6 Continuity measurement
• Turn off power to the circuit. Allow all capacitors to
discharge.
• Set the rotary switch to the continuity position.
• Connect the red test lead to the input jack and the black
lead to the COM jack.
• Connect the leads to the circuit under test.If the
measured resistance is less than 50Ω, the buzzer
will sound.
Warning
To prevent injury or damage to the meter,turn
off power to circuit and discharge all capacitiors
fully before making resistance measurements.
3.3.7 Diode test
Turn off power to the circuit. Allow all capacitors to
discharge.
• Set the rotary switch to the diode position.
• Connect the red test lead to the input jack and the black
lead to the COM jack.
• Connect the red test lead to the anode (+) and the black
lead to the cathode (-) of the diode and read the
measurement on the display.The meter will display “OL”
if the connection is reversed.
Warning
To prevent injury or damage to the meter,turn
off power to circuit and discharge all capacitiors
fully before making resistance measurements.
3.3.8 Battery test
• Set the rotary switch to the appropriate battery test range.
• Connect the red test lead to the input jack and the black
lead to the COM jack.
• Connect the red test lead to the positive (+) end and the
black lead to the negative (-) end of the battery and read
the measurement on the display.
Warning
To prevent injury or damage to the meter,do not
connent the meter to a battery with a voltage rating
exceeding 60V AC or 30V DC

4.2.6 DC Current
Resolution Accuracy
200mA 0.1mA
10mA10A
Measuring range
±(0.8% of reading +3 digits)
±(2.5% of reading +3digits)
If measured resistance
is less than 50Ω,
buzzer will sound
4.2.5 Continuity
Function Description
Description
Open circuit
voltage: 2.9V
Overload protection: 250V DC or AC (RMS)
Forward DC current:1mA
Reverse DC voltage: 2.9V
Display shows forward
voltage drop
4.2.4 Diode Test
Function DescriptionResolution
0.001V
Diode Test
Overload protection: 250V DC or AC (RMS)
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13
4.2.7 AC Current
Resolution Accuracy
200mA 0.1mA
10mA10A
Measuring range
±(1.0% of reading +3 digits)
±(2.5% of reading +3digits)
Overload protection: mA jack: F250mA H 250V fuse
10A jack: F10A H 250V fuse
Max input current: mA jack: 200mA AC rms
10A jack: 10A AC rms
When measuring current exceeding 2A, do not measure
for longer than 2 minutes continuously.Wait 10 minutes
to continue measurement.
4.2.8 Battery Test
Resolution Accuracy
12V 0.01V
0.01V
9V
Position
±(0.8% of reading +7 digits)
±(0.8% of reading +7digits)
1.5V 0.001V ±(3.0% of reading +5digits)
Overload protection: F250mA H 250V fuse
4.2.9 NCV Test
• Hold down the NCV button and move the NCV sensor
at the top of the unit next to the object being tested.
• When voltage is detected (>110V AC rms) the buzzer
will sound and the NCV indicator will flash.
Overload protection: mA jack: F250mA H250V fuse
10A jack: F10A H 250V fuse
Max input current: mA jack: 200mA DC
10A jack: 10A DC
When measuring current exceeding 2A, do not measure
for longer than 2 minutes continuously.Wait 10 minutes
to continue measurement.

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5. Maintenance
5.1 General Maintenance
This section provides basic information on maintaining
the meter, such as replacing fuses and the battery. Only
experienced and authorized personnel should make
repairs to the meter.
Warning
To avoid injury or damage to the meter,do not allow
moisture inside the case and remove test leads
before opening battery cover.
• Use a damp cloth to regularly clean the outside of the
meter. Do not use abrasives or chemical solvents.Dirty
or damp input jack can adversely affect readings.
• To clean input jacks, follow the following steps:
1. Turn off the instrument and remove the test leads.
2. Clear any dirt or other particles on the input jacks.
3. Use a cotton ball/swab with a lubricant (i.e. WD-40) to
clean off the contacts of the input jacks.
4. Use a separate cotton ball/swab for each jack to
prevent cross-contamination.
5.2 Replacing the Battery and Fuses
5.3 Replacing the Probe
Note:
• Even if the indicator doesn’t go off, voltage may still
exist.Do not use NCV detection as the sole
determination of a lack of voltage present in a
conductor.Detection could be impaired by socket
design, insulation, etc.
• When measuring voltage through input jacks, NCV
indicator may light up due to induced voltage.
• External environmental interference could cause false
NCV indications.
1. Under normal conditions, it is unnecessary to replace the fuse.
Don't replace it until the probes are unplugged and the power is
shut down. Take out the two screws of the rear cover to remove
the housing.
2. The specification of the fuse is:
F1 F 10A H 250V, F2 F 250mA H 250V
The replacement should be of the same specification.
3. The battery for this multimeter is 9V NEDA 1604 or 6F22.
The replacement should be of the same specification.
4. Don't put the instrument into use until the rear cover is screwed
after replacing battery or fuse.
To avoid electric shock, make sure the probes are disconnected
from the measured circuit before removing the rear cover.
Make sure the rear cover is tightly screwed before using the
instrument.
Warning
If insulation on probe is damaged, replace it.
Use meet EN 61010-031 standard, rated CAT II 600V, 10A or better probe.
WARNING
6. Accessories
•
•
•
•
Test Leads 1set
Package 1pcs
9V Battery 1pcs
User's Manual 1pcs

R-00-05-1048