Major tech MT975 User manual

INSTRUCTION MANUAL
MT975
SOUND LEVEL METER

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1. SAFETY INFORMATION
Read the following safety information carefully before
attempting to operate or service the meter.
Use the meter only as specified in this manual:
Environment conditions
①Altitude lower than 2000 meters
②Relatively humidity ≤90％RH
③Operation Ambient 0 ~ 40°C
Maintenance & Clearing
①Repair or servicing are not covered in this manual
and should be performed by a technician.
②Periodically wipe the case with a dry cloth. Do not
use solvents or eradicator on this instrument.
Safety symbols
Comply with EMC
2. FUNCTIONS DESCRIPTION
This Sound Level Meter is designed for noise project;
quality control; illness prevention and cure and all kinds of
environmental sounds measurement. It is applied to the
sounds measurement at factory; school; office; traffic
access and household, etc.
This unit confirms to the IEC61672-1 CLASS2 for
Sound Level Meters.
MAX & MIN measurements
Over range display

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Under range display
A & C Weighting
FAST & SLOW response
Analog AC/DC outputs for connection to frequency
analyzer or X-Y shaft recorder
3. SPECIFICATION
Standard applied: IEC61672 -1 CLASS2
Accuracy:±1.4dB
Frequency range:31.5HZ ~ 8KHZ
Dynamic range:50dB
Memory:32700
Level ranges: LO:30dB~80dB
Med:50dB~100dB
Hi:80dB~130dB
Auto:30dB~130dB
Frequency weighting: A/C
Time weighting: FAST ( 125ms ), SLOW ( 1s )
Microphone: 1/2 inch electret condenser microphone
Display: 4 digits LCD display with a resolution of 0.1dB
Display Update: 2 times/sec.
MAX hold: Hold the Maximum reading
MIN hold: Hold the Minimum reading
HOLD: Hold the readings
Alarm function: “OVER”is when input is more than upper
limit of range.“UNDER”is when input is
less than lower limit of range.
Analog output:AC/DC outputs from earphone outlet
AC=1Vrms ,DC=10mV/dB

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Data output: USB data traffic
Auto power off:Meter automatically shuts down after
approx. 15 minutes of inactivity.
Power supply: One 9V battery, 006P or NEDA1604 or
IEC 6F22.
Power life:About 30hours
Operation temperature and humidity:
0°C~40°C,10％RH~90％RH
Storage temperature and temperature:
-10°C ~+60°C，10％RH~75％RH
Dimension:278 (L) x 76 (W) x 50(H) mm
Weight : 350g
Accessories: Instruction manual, battery, screwdriver,
￠3.5mm earphone plug, windscreen,
software, USB cable.
4. NAME AND FUNCTIONS
①Windscreen
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15
16
17
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DC 9V
OUTPUT
CAL
REC
FAST
A/C
1
2
3
4
5
8
6
7
10
9
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②LCD：
SYMBOL FUNCTION
LCD 4 digits
MAX Maximum hold
MIN Minimum hold
OVER over range
UNDER under range
FAST Fast response
SLOW Slow response
dBA A-Weighting(responseto human sense)
dBC C-Weighting(response to machine monitor)
30—130 Range indicate
REC Recording data into computer
AUTO Auto level range selection
FULL Memory full
HOLD Data hold function
AutopoweroffPress the ”SETUP“ button to
disable power off
Low battery indicate

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③REC button
3.0 DATALOGGER function
Press “REC” button once the power has been switched on,
the display will show “REC” to start Data Recording，press
the button again to exit the record (Note: In order to avoid
data error, please don’t power it off under REC condition,
when the REC function is deleted then it can power off).
3.1 Adjusting DATALOGGER response
Press the button continuously before power it on，then
press ,it will be displayed as following: Press ’LEVEL’
button to adjust memory time,press ‘HOLD’ button to hold
the setup；
3.2 Data zero function
Select the button continuously before power it on，loosen the
button when the display showing’CLR’ after the meter
power on,which indicates that the data in DATALOGGER
has been deleted.
④SETUP button
4.0. The time chip adjustment

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Press‘SETUP’button and then power it on，when‘TIME’
symbol displays then loosen‘SETUP’， the meter will be
under time adjustment mode，at the time the display will
show the date as following:
Select the‘SETUP’button for a second time, the ‘hour
adjustment mode will be displayed：
Select ‘LEVEL’ to save the adjustment. Press the ‘HOLD’
function to save the setup;
Press the ‘SETUP’ button for a third time, the ‘hour’
adjustment mode will be displayed:
Press
(h-P =P.M,h-A=A.M)
‘LEVEL’ to make the adjustment，press‘HOLD’to save the
setup；

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Press the‘SETUP’button for a fourth time, the ‘date’
adjustment mode will be displayed
Press
‘LEVEL’ to make the adjustment，press ‘HOLD’ to keep the
setup；
Press the ‘SETUP’ button for a fifth time, the ‘month’
adjustment mode will be displayed：
Press
‘LEVEL’ to make the adjustment，press ‘HOLD’ to save the
setup；
Press the ‘SETUP’ button for a sixth time, the ‘year ’
adjustment mode will be displayed:
Press
‘LEVEL’ to make the adjustment，press ‘HOLD’ to save the
setup:
Press the ’SETUP’ button for a seventh time, the ‘time’

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adjustment mode will be displayed:
Press ‘HOLD’ to save the setup. The time and date will
return to the factory setup once the battery is flat or needs to
be replaced, if the time can’t be adjusted, initialize the time
chip first.
4.1. USB communications setting:
Turn on the meter, connect the unit to the computer. Select
the software COM3（COM4）. Press ‘SETUP’ and will
disappear from the display to indicate and disable auto
power off, that the USB data will start transmitting.
⑤FAST/SLOW button:
Time weighting selection
FAST: fast sampling measurement, 1 time per 125mS.
SLOW: slow sampling measurement, 1 time per second.
⑥MAX/MIN button:
Select the Maximum and Minimum hold button for once to
enter the MAX/MIN measurement, ‘MAX’ will be displayed
on the LCD screen. Maximum sound level will be captured
and held a until higher sound level is captured. Press the
button again, ‘MIN’ will appear on the LCD screen and the
minimum sound level will be captured and held until a
lower sound level is captured. Press the button one more

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time to exit MAX/MIN measurement.
⑦LEVEL button: Level range selection
Each time you press “LEVEL” button, the level range will
change between ‘Lo’ level, ‘Med’ level, ‘Hi’ level and ‘Auto’
level in that sequence.
⑧Backlight button
8.0．Turn the backlight on/off
8.1．DATALOGGER response setting;
Press the button continuously until‘INT’symbol appears.
Press‘LEVEL’to set up the data memory response and
press‘HOLD’to savethe setting.
⑨Frequency weighting select button
A：A-Weighting
C：C-Weighting
⑩HOLD button:
Press “HOLD” button, The hold function freezes the
reading in the display.
⑾Power button

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Turn the meter power ON/OFF
⑿External DC 9V power supply terminal
1 x DC 9V power supply.
Aperture size:
external diameter: 3.5mm
internal diameter: 1.35mm
⒀USB interface
USB signal output is a 9600 bps serial interface.
⒁AC/DC signal output earphone outlet
OUTPUT
GROUND
OUTPUT
AC
DC
AC: Output voltage: 1Vrms equivalent to each range
step.
Output impedance: 100Ω
DC: Output voltage: 10mV/dB
Output impedance: 1kΩ
⒂Calibration potentiometer（CALL）
Select the (CALL) function for external standard level
calibration adjustments

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⒃Tripod mounting screw
⒄Battery cover
⒅Microphone
1/2 inch Electret Condenser microphone
5. CALIBRATION PROCEDURES
①Make the following switch settings:
Frequency weighting: A-weighting
Time weighting: FAST
Level range: 50 ~100dB
②Insert the microphone housing carefully into the 1/2
inch insertion hole of the calibrator（94dB @ 1kHZ）.
③Turn on the calibrator switch and adjust the CALL
potentiometer of the unit 94.0dB is displayed.
NOTE: All products are well calibrated before shipment.
Recommended recalibration cycle: 1 year.
AcousticCalibrator
REC
FAST
A/C
DC 9V
OUTPUT
CAL

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6. MEASUREMENT PREPARATION
①Remove the battery cover on the back and insert
one 9V battery.
②Replace the back cover.
③The symbol will appear on the LCD screen
when the battery voltage drops below the operating
voltage and once the battery is flat.
④When the AC adapter is used, insert the plug of the
adapter （3.5φ）into the DC 9V connector on the
side panel.
7. OPERATING PROCEDURE
①Switch on the meter.
②Press the ‘LEVEL’ button to select the desired level,
based on ‘UNDER’ or ‘OVER’ do not appear on the
LCD.
③Select ‘dBA’ for general noise sound level and ‘dBC’
or measuring sound level of acoustic material.
④Select ‘FAST’ for instant sound and ‘SLOW’ for
average sound level.
⑤Select ‘MAX/MIN’ button for measuring maximum
and minimum noise level.
⑥Hold the instrument comfortably in your hand or fix
it to a tripod and measure sound level at a distance
of 1~1.5 meter.
8. NOTICE
i. Do not store or operate the instrument at ahigh
temperature and high humidity environment.
ii. When not in use for long time, remove the

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battery to avoid battery liquid leakage and damage
to the instrument.
iii. When using the instrument in the presence of wind,
it is essential to mount the wind absorber to avoid
undesirable signals.
iv. Keep the microphone dry and avoid sever vibration.
9. Accessories:
①CD with software
②USB interface cable
③screwdriver
10. Installing the software
1.0 Start windows
1.1 Insert the CD into the CD-drive.
1.2 Run SETUP.EXE installation program in file DISK1,
install it to the referred directory
1.3 Install CP210X drive software：
Connecting the meter with the computer by USB
interface, install CP2102 drive software in my computer
property:\hardware\facility management\ COM
CP210X USB.
USB Drive Installation
1. Copy the CP210XWIN Drivers to a certain directory,
such as: C:\ usb_driver.
2.Connect the USB to the computer, the Windows
system will show finding a new hardware. Choose
specific directory C:\ usb_driver according to the
instruction.
3. After Driver installation, a new COM port will be

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added to the Ports in the Device Manager. Port
number will be ranged following the primary COM
ports, such as: COM3 or COM4.
1.4 Once the drive software is installed, start the
application software, connect the meter to the
computer with the USB, then search for the COMX
port occupied by CP210X, press button, The ‘ ‘
symbol will not appear on the display，this will indicate
that the meter is transmitting data to the computer.
1.5 Enter the menu REAL TIME \‘SETUP’to set the
monitoring data (data volume, response, monitoring
time)
1.6 DATALOGGER menu:

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The computer reads the memory data in the meter
when REC mode does not appear on the display and
the connection is in order.