Mastech MS8250D User manual

MS8250D
DUAL DISPLAY
DIGITAL MULTIMETER
User’s Manual

Warning
01 0 2
1. Safety Information
Use caution and follow all safety guidelines to
prevent electric shock or damage to the meter.
Please ready carefully all instructions before use.
Instrument meets GB/T 13978-92 concerning digital
multimeter standards, along with G4B793.1-1995
(IEC-61010-1,IEC-61010-2-032)safety standards or
electrical measuring instruments with an over-voltage
category of CAT IV 600V,CAT III 1000V.
Follow all safety instructions to ensure safe use and long
life of the instrument.
1.1 Preparation
1.1.1 When using the meter, follow all standard safety
guidelines:
- For universal protection again electric shock.
- To prevent the misuse of the instrument.
1.1.2 Check the meter for damage during transit.
1.1.3 Test leads must be in good condition.Check the
insulation and tips before use.
1.1.4 Safety can only be guaranteed with leads provided.
If leads need to be replaced, they must be replaced
with leads of same electrical specifications.
1.2 Using the Meter
1.2.1 Always set the meter to the proper function and
range first.
1.2.2 Never exceed protection limits indicated for each
measurement.
1.2.3 Keep fingers behind the probe barriers while
measuring.
1.2.4 Always be careful when working with voltages
above 60V DC or 30V AC RMS.
1.2.5 Never measure voltages that might exceed 600V
DC/AC above earth ground.
1.2.6 In manual range, if the circuit value is unknown,
start the meter at the maximum range and then
adjust accordingly.
1.2.7 Remove the leads from the circuit first before
switching between functions.
1.2.8 Do not power on circuit while measuring resistance,
capacitance, diodes and continuity.
1.2.9 Never connect the meter’s leads across a voltage
source while the rotary switch is in the resistance,
capacitance, diode or continuity mode.
1.2.10 Do not measure capacitance before capacitors
are discharged.
1.2.11 Do not operate the meter near explosive gas,
vapor or dust.
1.2.12 Stop using the meter if any abnormality is observed.
1.2.13 Do not use the meter unless the battery cover is
securely fastened to the meter.
1.2.14 Avoid direct exposure to sunlight to ensure
extended life of the meter.

03 0 4
1.3 Safety Symbols
1.4 Maintenance
1.4.1 To avoid electric shock or personal injury, repairs/
servicing not covered in this manual should be
performed only by qualified personnel.
1.4.2 Remove test leads from any circuit before opening
battery cover.
1.4.3 To avoid false readings that may become
dangerous, replace the battery as soon as the
ymbol appears.
1.4.4 Clean the meter using a damp cloth and mild
detergent only; do not use abrasives or chemical
solvents.
1.4.5 Always move rotary switch to OFF when not using
the meter.
1.4.6 If meter is not going to be used for an extended
period of time, remove battery to prevent damage
to the meter.
2. Description
-The MS8250D is a portable, hand-held yet professional
meter that features True RMS measurement display,
AC/DC current, AC/DC voltage, Frequency,
Capacitance, Resistance, Continuity, Duty Ratio, Diode
Testing and a USB adapter for recording readings on a
PC. This Meter is easy to use even with one hand, s
uitable for professional users or amateurs, and ideal for
school or home use.
- Both auto and manual range.
- Display hold
- True RMS for AC voltage/current measurements
- Relative measurement
- Maximum measurement
- Minimum measurement
- Display frequency when measuring AC voltage/current
- Automatic Power Off
Important safety information, please refer
to user ’s manual
Caution when testing on live conductors
Double insulation protection (category II)
This meter has met IEC61010-1 standard
with an overvoltage category (600V CAT IV)
and pollution degree 2.
CAT IV
Double insulation protection (category II)
Ground
2.1 Part Name
(1)
(2)
(3)
(4)
(5)
(6)
(7)
USB interface
NCV detection indicator
LCD display
Function buttons
Rotary switch
Input sockets
NCV detection sensor
Complies with U.S. and Canadian safety
standards

05 0 6
2.2 2 Buttons/Input jack description
HOLD: keep current reading on the display
FUNC: switch between functions or AC/DC measurement
RANGE: switch between auto/manual ranges
REL: display relative measurement
MAX/MIN: switch between max/min measurement display
:turn on/off backlight
OFF:Power off position
:input jack for voltage, resistance, capacitance,
diode, continuity, frequency and duty cycle
measurement
:common terminal
: input jack for current measurement (<660mA)
:input jack for current measurement (<10A)
COM
μAmA
10A
VHz%
2.3 LCD display
1
2
4
5
6
3
7

07 0 8
Alternating current
Direct current
Diode
Continuity
Auto range
Maximum display
Minimum display
Low battery
Percentage (duty cycle)
Hertz, kilohertz (frequency)
Millivolts, volts (voltage)
Micro amps, milliamps, amps (current)
Nanofarad, microfarad, millifarad (capacitance)
Ohms, kilaohms, megaohms
Relative display
AUTO
MAX
MIN
%
Hz, kHz
mV, V
REL
Ω, kΩ, MΩ
nF, μF, mF
μA, mA, A
3. Specifications
Instrument should be calibrated annually at 18°C~28°C
and relative humidity of <75%.
NCV Non-contact voltage detection
USB interface active
Auto power off
3.1 General Specifications
3.1.1 Auto and manual range
3.1.2 Full range overload protection
3.1.3 Max. voltage between terminal and
ground: 600V DC or AC rms
3.1.4 Operating altitude: 2000m max.
3.1.5 Display: 6600 count LCD
3.1.6 Polarity indication: automatically displays “-”
3.1.7 Over range indication: “OL” or “-OL”
3.1.8 Sample rate: approx. 0.4s/analog bar
graph: approx. 0.04s
except for current measurement: approx.
1s/bar graph: 0.1s
3.1.9 Unit display: functions and unit power
3.1.10 Auto power off time: approx. 15 min.
3.1.11 Power supply: 9V battery
3.1.12 Low battery indication: display shows“ ”
3.1.13 Temp. coefficient: less than 0.1 x accuracy/°C
3.1.14 Operating temperature: 0~40°C
3.1.15 Storage temperature: -10~50°C
3.1.16 Dimensions: 180x86x52mm
3.1.17 Weight: approx. 250g (without battery)

09 1 0
3.2 Technical Indicators
3.2.1 True RMS characteristics
3.2.1.1 For non-sinusoidal signal measurement, the
Meter provides more accurate measurement than
the traditional averaging method.
3.2.1.2 If in AC current mode, the Meter may display a
random reading between 1 and 50 when the input
is not active. This will not affect the accuracy of
measurement.
3.2.1.3 True RMS requires a minimum input level, AC
current or voltage should be 2%~100% of the
maximum level.
3.2.2 DC Voltage
Resolution
0.1mV
Accuracy
±(0.8% reading + 3 digits)of
660mV
0.001V
0.01V
0.1V
6.6V
66V
600V ±(0.5% reading + 5 digits)of
Range
- Input impedance: 10M
- Overload protection: 660mV range: 250V DC or AC rms.
6.6V-1000V ranges: 1000V DC or 1000V AC rms.
- Max. input voltage: 1000V DC
Ω
0.1V1000V
3.2.3 AC Voltage
Resolution
0.1mV
Accuracy
±(1.5% reading + 5 digits)
660mV
0.001V
0.01V
0.1V
6.6V
66V
600V
±(1.2% reading + 5 digits)
Range
±(1.5% reading + 5 digits)
- Input impedance: 10MΩ
- Overload protection: 660mV range: 250V DC or AC rms.
6.6V-1000V ranges: 1000V DC or 1000V AC rms.
- Max. input voltage: 1000V DC
- Frequency response: 50 ~ 60Hz
- Response: True RMS
0.1V
1000V ±(1.5% reading + 5 digits)
3.2.4 Resistance
Resolution
0.1Ω
Accuracy
660Ω
0.001kΩ
0.01kΩ
0.1kΩ
6.6kΩ
66kΩ
660kΩ
6.6MΩ
±(0.8% reading + 5 digits)
Range
±(1.5% reading + 5 digits)
- Open circuit voltage: approx. 0.4V
- Overload protection: 250V DC or AC rms.
66MΩ0.1MΩ
0.001MkΩ

11 1 2
3.2.5 Capacitance
Resolution
0.001nF
Accuracy
6.6nF
0.01nF
0.01µF
0.01µF
66nF
66µF
660µF
±(4.0% reading + 5 digits)
Range
- Overload protection: 250V DC or AC (RMS)
0.1µF
0.1nF660nF
6.6µF
6.6mF
66mF
0.001mF
0.01mF
±(3.0% reading + 3 digits)
±(4.0% reading + 5 digits)
3.2.6 Diode Test
Resolution Function
Range
Display approximate diode
forward voltage value
0.001V
- Forward DC current: approx. 1mA
- Reverse DC voltage: approx. 3.3V
- Overload protection: 250V DC or AC rms.
3.2.7 Circuit Continuity Test
Resolution Function
Range
If the resistance of circuit to be
measured is less than 30Ω, the
meter's built-in buzzer will
sound.
0.1Ω
- Open circuit voltage is about 1.2V
- Overload protection: 250V DC or AC (RMS)
3.2.8 Frequency
3.2.8.1 In V mode:
Resolution Accuracy
66Hz
±(1.5% reading + 5 digits)
Range
660Hz
10kHz
0.01Hz
0.1Hz
0.001kHz
0.01kHz
6.6kHz
- Frequency range:10Hz~10kHz
- Input voltage range: >0.2V AC(rms)(as measured
frequency increases,voltage will also increase)
3.2.8.2 Pass Hz grade:
Resolution Accuracy
66Hz
±(1.5% reading + 5 digits)
Range
660Hz
6.6kHz
660kHz
6.6MHz
66MHz
0.01Hz
0.1Hz
0.001kHz
0.01kHz
0.1kHz
1kHz
10kHz
66kHz
- Overload protection:250V DC or AC rms.
- Measurement signal: 3Vpp AC
3.2.8.3 Duty Ratio
Resolution Accuracy
1-99%
Range
0.1% ±2.0%

13 1 4
3.2.9 DC Current
Resolution Accuracy
660µA
±(1.0% reading + 5 digits)
Range
66mA
10A
0.1µA
1µA
10µA
10mA ±(2.0% reading + 5 digits)
6600µA
660mA 100µA
- Overload protection:
µA/mA jack: F 600mA/1000V. A jack: F10A/600V.
- When measuring current larger than 5A, do not continue
measurement for greater than 10s. Wait 1 min. after
measurement before resuming.
3.2.10 AC Current
Resolution Accuracy
660µA
±(1.5% reading + 5 digits)
Range
66mA
10A
0.1µA
1µA
10µA
10mA ±(3.0% reading + 5 digits)
6600µA
660mA 100µA
- Overload protection:
µA/mA jack: F 600mA/1000V. A jack: F10A/600V.
- Frequency response:50 ~ 60Hz
- Response: True RMS
- When measuring current larger than 5A, do not continue
measurement for greater than 10s. Wait 1 min.after
measurement before resuming.
4. Using the Meter
4.1 Data Hold
4.1.1 During measurement, if you want to keep the
reading on the display, press“HOLD”and the
reading will be held.
4.1.2 Press“HOLD”again to release the hold.
4.2 Manual Range
4.2.1 In voltage, current, resistance, capacitance, and
frequency modes, the default range is auto.
4.2.2 Press“RANGE”to switch to manual range.Each
press of the button increases the range, and returns
to the lowest range when pressed in the largest
range.
4.2.3 Hold down“RANGE”for 1 second to return to auto
range.
4.2.4 When in Max/Min modes, pressing“RANGE”to
return to normal measurement.
Note:
Frequency cannot be set to manual range.
4.3 Relative Mode
4.3 1 Press“REL”to enter relative mode.The meter stores
the measured value when the button was pressed
and compares it to the currently measured value
(rel = current reading - stored reading).
.
4.4 Maximum/Minimum Mode
4.4.1 Press MAX/MIN in any range to show the maximum
value recorded; press“MAX/MIN”again to show the
minimum value recorded; press“MAX/MIN”a third
time to return the display to normal.
“ ”

15 1 6
4.4.1 In voltage and current modes, press“FUNC”to
switch between AC and DC modes.
4.4.1 In the multi-function position, press“FUNC”to switch
between resistance, diode and continuity modes.
4.5 Function Switch
4.6 Backlight
4.7 Automatic 9ower-off
4.6.1 Press “ ” key, turn on or off backlight.
4.7.1 If the meter is not used for 30 minutes, the meter
will automatically turn itself off to save battery power.
4.7.2 To turn the meter back on, press any button.
4.7.3 Holding FUNC when turning on the meter will
disable auto power off.
“ ”
4.9 NCV (Non-Contact Voltage detection)
4.8 USB Communication
4.8.1
4.8.2
4.8.3
Install the included software and USB driver
( See PC CD-ROM software user’s guide) on a PC.
Use the included USB cable to connect the meter
to the PC; the symbol appears on the display.
Open the installed software and the meter will begin
sending the measured data to the software.
4.9.1 Move the rotary switch to the NCV position.
4.9.2 Move the NCV sensor (top of the meter) toward the
object to be tested. If the sensor detects voltage
greater than 110VAC (rms), the NCV indicator will
flash and the meter will beep.
Note:
1.Even without indication, voltage may still exist. Do not
solely rely on NCV detection to determine in voltage
exists. Detection may be affected by socket design,
insulation thickness or other factors.
2.NCV indicator may go off when measuring voltage due
to the presence of induced voltage.
3.Interference sources may accidentally trigger NCV
detector.
4.10 DC/AC Voltage
Voltage is the potential difference between two points.
The polarity of AC voltage changes over time where DC
voltage polarity does not.
DC voltage ranges: 660.0mV、6.600V、.00V、0.0V.
1000V AC voltage ranges: 660mV、6.600V、66.00V、
660.0V. 1000V. 660mV range can only be entered through
manual range.
Measuring DC/AC voltage:
4.10.1 Move the rotary switch to the position.
4.10.2 Connect the red test lead to the V jack and the
black lead to the COM jack.
4.10.3 Connect the leads in parallel with the circuit under
test.
4.10.4 The measured voltage will be displayed. For DC
measurement, the polarity of the red lead will be
indicated.
4.10.5 Press“FUNC” to switch between DC and AC
voltage.
66 66

17 1 8
4.11 Resistance
Resistance ranges: 660.0、6.600k、66.00k、660.0k、
6.600M、660.00M.
To measure resistance:
4.11.1 Move rotary switch to the position.
4.11.2 Connect the red test lead to the Ω jack and the
black lead to the COM jack.
4.11.3 Connect leads to circuit under test.
4.11.4 The measured resistance will be displayed.
4.12 Continuity
While in resistance mode, press “FUNC” to switch to
continuity mode.
4.12.1 Connect the red test lead to the Ω jack and the
black lead to the COM jack
4.12.2.Connect leads to circuit under test.
4.12.3.If the measured resistance is less than 50Ω, the
meter’s buzzer will sound.
4.13 Diode Test
While in continuity mode, press “FUNC” to switch to
diode mode.
4.13.1 Connect the red test lead to the V jack and the
black lead to the COM jack.
4.13.2.Connect leads across the diode under test.
4.13.3.The display shows the approx. forward voltage
drop.
Ω
4.14 Capacitance
4.15 Frequency and Duty Cycle
Frequency ranges: 60Hz, 600Hz, 6kHz, 60kHz, 600kHz,
6MHz, 60MHz.
Measuring Frequency:
4.15.1 Move the rotary switch to the Hz% position.
4.15.2 Connect the red test lead to the Hz% jack and the
black lead to the COM jack.
4.15.3 Connect the leads across the circuit under test.
4.15.4 The measured frequency will be displayed.
4.15.5 Press “FUNC” to switch to duty cycle.
4.15.6 Repeat steps 2-4 to measure duty cycle.
4.16 DC/AC Current
Current ranges: 660A, 6600A, 66.00mA, 660.0mA,
10.000A.
4.16.1 Turn off power to the circuit and discharge all
capacitors fully.
4.16.2 Move the rotary switch to the appropriate current
position (µA, mA, or A)
4.16.3 Connect the black test lead to the COM jack.If the
current to be measured is less than 600mA,
connect the red test lead to the µAmA jack.If the
current to be measured is between 600mA and
10A, connect the red test lead to the 10A jack.
Capacitance ranges: 6.6nF、66.00nF、660.0nF、
6.600F、66.00F、66.0F、6.600mF and 66mF.
Measuring capacitance:
4.14.1 Move the rotary switch to the position.
4.14.2 Connect the red test lead to the jack and the
black lead to the COM jack.
4.14.3 Connect the leads across the capacitor for
measurement
4.14.4 The measured capacitance will be displayed