Triplett MM350 User manual

User Manual
MM350
True RMS Auto Ranging Digital
Multimeter
Introduction
Congratulations on your purchase of the Triplett MM350 True RMS Auto
Ranging Digital Multimeter.
This instrument performs AC/DC voltage, AC/DC Current, Resistance, Audible
Continuity, Diode, Temperature measurements and Frequency measurements,
it is a 3 3/4 digits, 3999 counts Auto Ranging DMM.

Safety
•Circuits under test must be de-energized and isolated before
connections are made (except for voltage measurements).
•Circuit connections must not be touched during a test. Use extreme
caution when working near bare conductors and bus bars. Accidental
contact with conductors could result in electrical shock.
•Use caution when working near voltages above 60VDC or 30VACrms.
•After insulation tests, capacitors must be discharged.
•Test leads (including alligator clips) must be in good working order,
clean and without broken or cracked insulation.
•When servicing, use only specified replacement parts.
International Safety Symbols
Caution, refer to this manual before using this meter
Dangerous Voltages
Meter is protected throughout by double or reinforced insulation
ELECTRICAL SYMBOLS
DC (Direct Current).
AC (Alternating Current).
DC or AC
Important safety information.
Refer to the manual.
Dangerous voltage maybe present.
Earth ground.
Low battery
Fuse.

Diode
Continuity test
°C
Centigrade
°F
Fahrenheit
AUTO
Auto range
Conforms to European Union directive.
Double insulated.
APO
APO auto power off
Battery capacity
▲
Relative test
Data hold
Meter Description
1) 3 3/4 digit LCD, with a max. reading
of 3999
2) Range Button
The meter defaults to the auto range
mode when you measure the
voltage, current, resistance or
capacitance. When the meter is in
the auto range mode, “AUTO” is
displayed.
To enter and exit the manual range
mode:
a. Press “ RANGE” button
The meter enters the manual range
mode and the symbol “AUTO” turns
off.
b. To exit the manual range mode,
press and hold down the “RANGE”
button for 2 seconds, the meter returns to the auto range mode and the symbol
“AUTO” is displayed.
3) “Select.” Button
When you measure the current, pressing this button will switch the meter
between DC function and AC function.

When you measure the diode or the continuity, pressing this button will switch
the meter between the diode and the continuity functions.
“ ” Button
After pressing the button, the present reading is held on the display, meanwhile
“ ” is displayed on the LCD as an indicator. To exit the Hold Mode, press
the button again and the indicator “ ” will disappear.
pressing the button more then 2 second，Backlight turned on，pressing the
button more then 2 second again，Backlight turned off
4) “Max/Min”Button: After pressing the button Displays the maximum and minimum
values during the test. The maximum and minimum values are cleared after the
changes the test function,or meter be off.
5) Relative Button
This Meter will display relative measurements in all functions, except frequency.
6) Hz% button
When you measure the Hz%, pressing this button will switch the meter between
HZ function and duty cycle function.
When you measure the ACV, pressing this button will switch the meter will show
the frequency of the AC voltage.
7) Function/Range Switch
This switch can be used to select desired function and range.
8) “A” Jack
Plug-in connector for the red test lead for Current (200mA ~ 10A)
measurements.
9) “COM” Jack
Plug-in connector for black(negative) test lead.
10) “INPUT” Jack
Plug-in connector for the red test lead for all measurements except
current(≥200mA) measurements.

Operation
Measuring Voltage
1) Connect the black test lead to the “COM” jack and the red to the “INPUT” jack.
2) Set the function switch to V or V range.
Select auto range or manual range with the “RANGE” button.
3) In manual range, if the voltage magnitude to be measured is unknown
beforehand, select the highest range.
4) Connect the test leads across the source or load to be measured.
5) Read LCD display. The polarity of the red lead connection will be indicated when
making a DC measurement.
Note: a. In small range, the meter may display an unstable reading when the test
leads have not been connected to the load to bemeasured. It is normal and
will not affect the measurements.
b. In manual range mode, when the meter shows the over range symbol “OL”,
a higher range must to be selected.
c. To avoid damage to the meter, don’t measure a voltage which exceeds
600Vdc (for DC voltage measurement) or 600Vac (for AC voltage
measurement).
Measuring Current
1) Connect the black test lead to the “COM” jack. If the current to be measured is
less than 200mA, connect the red test lead to the “INPUT” jack. If the current is
between 200mA and 10A, connect the red test lead to the “10A” jack instead.
2) Set the range switch to desired µA , mA or A range.
If the current magnitude to be measured is not known beforehand, set the ranges
switch to the highest range position and then reduce it range by range until
satisfactory resolution is obtained.
3) Select DC current measurement or AC current measurement with the “Select”
Button.
4) Select auto range or manual range with the “Range” button. In manual range, if
the current magnitude to be measured is not known beforehand, select the
highest range.
5) Connect test leads in series with the circuit to be measured.
6) Read the reading on the display. For DC current measurement, the polarity of the
red test lead connection will be indicated as well.

Note: When the display shows the over range symbol “OL”, a higher range must be
selected.
Measure Resistance
1) Connect the black test lead to the “COM” jack and the red to the “INPUT” jack
(Note: The polarity of the red test lead is positive “+”).
2) Set the range switch to “ ”position
3) Set the “Select” button to“ ”range
4) Select auto range or manual range with the “Range” button. In manual range, if
the current magnitude to be measured is not known beforehand, select the
highest range.
5) Connect the test leads across the load to be measured.
6) Read the reading on the display.
Note: a. For resistance measurements >1MΩ, the meter may take a few seconds to
stabilize reading. This is normal for high-resistance measurement.
b. When the input is not connected, i.e. at open circuit, the symbol “OL” will
be displayed as an over range indicator.
c. Before measuring in-circuit resistance, be sure that the circuit under test
has all power removed and all capacitors are fully discharged.
Continuity Test
1) Connect the black test lead to the “COM” jack and the red to the “INPUT” jack
(Note: The polarity of the red test lead is positive “+”).
2) Set the range switch to “ ” position
3) Press the “Select” Button to select continuity measurement mode, and thesymbol
“ ” will appear as an indicator.
4) Connect the test leads across the load to be measured.
5) If the circuit resistance is lower than about 30Ω, the built-in buzzer will sound.
Diode Test
1) Connect the black test lead to the “COM” jack and the red to the “INPUT” jack
(Note: The polarity of the red test lead is positive “+”).
2) Set the range switch to “ ” position.
3) Press the “Select” Button to select continuity measurement mode, and the symbol

“ ” will appear as an indicator.
4) Connect the red test leadto the anode of the diode to be tested andthe black test
lead to the cathode.
5) The meter will show the approximate forward voltage of the diode. If the
connections are reversed, “OL” will be shown on the display.
Capacitance Measuring
1) Connect the black test lead to the COM jack and the red to the “INPUT” jack.
2) Set the range switch to “ ”position
3) Press the “Select” Button to select continuity measurement mode, and the symbol
“mF” will appear as an indicator.
4) Connect test leads across the capacitor under measure and be sure the polarity of
connection is observed.
Note: When the capacitance under measure is above 100uF, it needs at least 10
seconds to make readings stable.
Measuring Temperature
1) Set the range switch to “℃”or “℉”range.
2) Insert the black (or “-“) plug of the K type thermocouple to the “COM” jack, and
the red( or “+”) plug to the “INPUT” jack.
3) Carefully touch the end of the thermocouple to the object to be measured.
4) Wait a while, read the reading on the display.
Frequency / Duty cycle measure
1) Connect the black test lead to the COM jack and the red to the “INPUT” jack.
2) Set the range switch to “Hz %” range.
3) Press the “Select” Button to select “Hz” or “duty cycle”mode
4) Connect test leads across the source or load under measurement.
NOTE: The input voltage should be between 200mV and 10V rms AC. If the voltage
is more than 10V rms, reading may be out of the accuracy range.
Auto Power Off
If you don’t operate the meter for about 15 minutes, it will turn off automatically. To
turn on it again, just rotate the range switch or press a button.
In the power off state, press and “Select” button to Rotary range switch, you can
cancel the auto power off function, “APO” symbol disappear from the LCD.

Specifications
Accuracy is guaranteed for 1 year 23°C±5°C less than 80%RH
5-1. DC VOLTAGE (Auto ranging)
Range
Resolution
Accuracy
400mV
0.1mV
±(0.8% of rdg + 5dgts)
4V
1mV
±(0.8% of rdg + 3dgts)
40V
10mV
400V
100mV
600V
1V
±(1.0% of rdg + 5dgts)
Input Impedance: 10MΩ
Overload Protection: 600V DC or 600AC rms
(200mV range: 250V DC/AC rms)
Max. Input voltage: 600V DC
5-2. AC VOLTAGE (Auto ranging)
Range
Resolution
Accuracy
400mV
1mV
±(1.2% of rdg + 5dgts)
4V
1mV
±(1.0% of rdg + 8dgts)
40V
10mV
400V
100mV
600V
1V
±(1.2% of rdg + 8dgts)
Input Impedance: 10MΩ
Frequency Range: 40Hz ~ 400Hz
Overload Protection: 600V DC or 600AC rms
Response: Average, calibrated in rms of sine wave
Max. Input voltage: 600V AC rms
5-3. TEMPERATURE
Rang
e
Resolution
Accuracy
-40 ~
1370°
C
1°C
-40°C~150°C:±(2.5% + 4)
150°C~1370°C:±(2.5% + 4)
-40 ~
1°F
-40°F~302°F:±(2.5% + 4)

2000°
F
302°F~2000°F:±(2.5% + 4)
NOTE: Different temperature sensors are configured in different temperature test
ranges, and normal temperature sensors are provided for standard configuration
5-4. DC CURRENT
Range
Resolution
Accuracy
400µA
0.1µA
±(1.2% of rdg + 8dgts)
4000µA
1µA
40mA
10µA
400mA
100µA
4A
1mA
10A
10mA
Overload Protection:
µA and mA ranges: F0.5A/600V fuse
4A and 10A ranges: F10A/600V fuse
Max. Input Current:
“INPUT” jack: 200mA
“A” jack: 10A
(For measurements>5A: duration <10 seconds, interval >15 minutes)
Voltage Drop: 400µA, 40mA and 4A ranges: 40mV
4000µA, 400mA and 10A ranges: 400mV
5-5. AC CURRENT
Range
Resolution
Accuracy
400µA
0.1µA
±(1.5% of rdg + 8dgts)
4000µA
1µA
40mA
10µA
400mA
100µA
4A
1mA
±(2.0% of rdg +10dgts)
10A
10mA
Overload Protection:
µA and mA ranges: F0.5A/600V fuse
4A and 10A ranges: F10A/600V fuse
Max. Input Current:
“INPUT” jack: 200mA
“A” jack: 10A
(For measurements>5A: duration <10 seconds, interval >15 minutes)
Voltage Drop: 400µA, 40mA and 4A ranges: 40mV
4000µA, 400mA and 10A ranges: 400mV

Frequency Range: 40Hz ~ 400Hz
Response: Average, calibrated in rms of sine wave
5-6. RESISTANCE (Auto Ranging)
Range
Resolution
Accuracy
400Ω
0.1Ω
±(1.5% of rdg + 3dgts)
4KΩ
1Ω
40KΩ
10Ω
400KΩ
100Ω
4MΩ
1KΩ
40MΩ
10KΩ
Open Circuit Voltage: about 0.25V
Overload Protection: 250V DC/AC rms
5-7. Diode and Continuity
Range
Introduction
Remark
The approximate forward
voltage drop will be
displayed
Open circuit
voltage: about
1.5V
The built-in buzzer will
sound if the resistance is
less than about 30Ω.
Open circuit
voltage: about
0.5V
Overload Protection: 250V DC/AC rms
For continuity test: When the resistance is between 50Ω and 100Ω, the buzzer may
sound or may not sound. When the resistance is more than 100Ω, the buzzer won’t
sound.
5-8. Capacitance
Range
Resolution
Accuracy
40nF
10pF
±(8% of rdg + 10dgts)
400nF
100pF
±(5% of rdg + 5dgts)
4uF
1nF
40uF
10nF
100uF-
2mF
100nF
5-10. FREQUENCY
Range
Accuracy
5/50/500/5K
50K/500K/5MHz
±(1.0% of rdg + 3dgts)

General specifications
Display : LCD, 3999 counts updates 2/sec
LCD Size : 55 x 31mm
Polarity Indication : “-” displayed automatically
Over-range Indication : “OL” displayed
Low Battery Indication : “ ” displayed
Range select : auto or manual
Operation Temperature : 0°C to 40°C, less than 80%RH
Storage Temperature: -10°C to 50°C, less than 85%RH
Battery Type : 1.5V x 3, AAA size
Dimension (H×W×D) : 5.7 x 2.8 x 1.4" (145 x 70 x 35mm)
Weight : 5.5oz. (157g)
Approvals
8. BATTERY REPLACEMENT
If the sign “ ” appear on the display, it indicates battery should be replaced.
Remove screws and open the back case, replace the exhausted battery with new
batteries (Size AAA, 1.5V x3 or equivalent).
9. ACCESSORIES
User Manual, Test leads, Type K Thermocouple with Banana Connectors
10. FUSE REPLACEMENT
Fuse rarely needs replacement and is blown almost always as a result of operator’s
error. This meter uses a fuse: F1:500mA/600V and F2: 10A/600V fast action. To
replace the fuses, open the meter back cover, replace the damaged fuse with a new
fuse of the specified ratings. Reinstall the battery cover and lock this cover.
Warranty Information
Triplett / Jewell Instruments extends the following warranty to the original purchaser of
these goods for use. Triplett warrants to the original purchaser for use that the products sold
by it will be free from defects in workmanship and material for a period of (1) one year from
the date of purchase. This warranty does not apply to any of our products which have been
repaired or altered by unauthorized persons in any way or purchased from unauthorized
distributors so as, in our sole judgment, to injure their stability or reliability, or which have
been subject to misuse, abuse, misapplication, negligence, accident or which have had the
serial numbers altered, defaced, or removed. Accessories, including batteries are not
covered by this warranty Copyright ©2019 Triplett