DEASOMIYE T21D Auto Ranging Digital Multimeter Instruction Manual

DEASOMIYE T21D Auto Ranging Digital Multimeter

Specifications:

• Model: T21D
• Type: Auto-ranging Digital Multimeter with TRUE RMS
• Power Source: Three AAA 1.5V batteries
• Maximum Voltage Measurement: 600V
• Fuse: F200mA/250V

Product Usage Instructions

Safety Information:
Before using the T21D multi-meter, ensure you comply with all standard safety regulations:

1. Use the provided test leads and check their integrity before each use.
2. Avoid measuring resistance, capacitance, or performing buzzer tests on live circuits.
3. Check the fuse before conducting current measurements.
4. Power off the circuit before connecting the meter.

Battery Installation and Maintenance:
Install three AAA 1.5V batteries correctly in the compartment. Replace low voltage batteries immediately to prevent incorrect measurements and potential electric shock.

Input Protection Measures:
Be aware of voltage limits when measuring different parameters:

• Voltage Measurement: Do not exceed 600V.
• Frequency, Resistor, Buzzer, Diode Measurement: Limit voltage to 250 ACV or equivalent RMS voltage.
• Current Measurement: Fuse (F200mA/250V) protects during uA and mA measurements.

General Maintenance:
Before cleaning or servicing the multimeter, disconnect all power sources. Use a damp cloth with mild detergent for cleaning; avoid abrasives or solvents. Keep input sockets clean and dry for accurate readings.

FAQ:

• Q: What should I do if the ‘low voltage’ symbol appears on the display?
  A: Replace the batteries immediately to prevent incorrect measurements and potential electric shock.

• Q: Can I measure voltages above 600V with this multimeter?
  A: No, do not exceed 600V when measuring voltages to ensure safety and proper functioning of the instrument.

Thank you for your purchase of the T21D multi-meter. We hope that this precision instrument will be one of the supporting tools contributing to your work efficiency. Before using the device, please read the manual carefully and if you have any questions, kindly contact our customer service via email at HEMITEK2022@126.com
Thank you for your support.

INTRODUCTION

• The T21D multi-meter is a precise, safe, and fast-response multi-function instrument, embedded with a special IC of up to 6,000 counts. This IC is composed of high-precision AC/DC converter with a high-speed digital processor for true RMS calculation for AC 1KHz. This calibrated, high-quality, and high-resolution multi-meter consistently provides fast and precise measurements.
• Made for industrial, automotive, and domestic use, the user-friendly T21D has many measurement functions to meet the usage requirements of all technicians, electricians and engineering students.
• The T21D can be used to measure AC/DC voltage and current, resistance, capacitance, temperature, diodes, and circuit continuity tests. It is equipped with a backlight for the user to read the measurements in any lightning condition.

Panel Indication

Symbols instructions

SAFETY INFORMATION

Safety instructions
*When using this meter, the user must comply with all the standard safety regulations as follows:

1. Protection against electric shocks.
2. Preventing the misuse of the instrument’s safety procedures.

*To ensure your personal safety, please use the test leads provided with the meter, please check before use, and make sure they are intact.

Safety symbols:

Safety notices:

• Please note that using the multi-meter near devices with large electromagnetic disturbances measurement will be unstable and may cause output errors.
• Do not use it when the multi-meter test leads are broken.
• If the multi-meter is not used correctly, the safety functions provided by the meter may fail.
• Care must be taken when working around bare conductors or buses.
• Do not use this instrument near explosive gas vapors or in a dusty environment.
• The correct input function must be used to measure the range.
• The input value must not exceed the limit of the value specified for each range to prevent damage to the instrument.
• Do not touch the unused input when the instrument is connected to the circuit under test.
• When the measured voltage exceeds 60 V/DC or 30 V/AC, use it with caution to prevent electric shock.
• When measuring with test leads, place your fingers behind the  guard ring of the test.
• Before converting the range, please ensure that the test leads have left the circuit under test.
• Before carrying out a resistance, diode, capacitance measurement or continuity test, the circuit under test must be powered off and all high-voltage capacitors in the circuit under test should be discharged.
• Do not measure the resistance, capacitance on a live circuit or perform a buzzer test.
• Before conducting the current measurement, the fuse of the multi-meter should be checked.
• Before connecting the meter to the circuit under test, the power of the circuit under test should be turned off.
• When performing TV repairs or measuring power conversion circuits, care must be taken in the high-amplitude voltage pulses in the circuit under test to avoid damage to the meter.
• The T21D multi-meter is powered by three AAA 1.5V batteries. Please install the battery correctly in the battery compartment of the meter.
• When the battery ‘low voltage’ symbol appears, replaced the battery immediately because insufficient battery power can provide incorrect measurement. It may also cause electric shock or personal injury.
• When measuring voltages, do not exceed 600V. Do not use the instrument when the instrument’s housing or part of the housing is removed.

Maintenance

• When opening the instrument case or removing the battery cover, pull out the test leads first.
• Only specified replacement parts are to be used to service the multi-meter.
• Before opening the meter, all relevant power must be disconnected, do ensure that there is no static electricity left, this is to avoid any damage to the meter.
• Instrument calibration and maintenance of the multi-meter must be done by qualified professionals.
• When opening the multi-meter housing, some capacitance in the multi-meter must be checked even after the instrument is turned off, this is because dangerous voltages are still stored in the capacitors.
• If there is any abnormality in the multi-meter, please stop using it and send it for repair immediately.
• When not in use for a long period of time, please remove the battery, and avoid storing the multi-meter in areas of high humidity and temperature.

Input protection measures

• The limit voltage is 600V when the voltage is measuring.
• The limit voltage is 250 ACV or the equivalent RMS voltage when the frequency, resistor, buzzer, or diode is measuring.
• The fuse (F200mA/250V) will work to protect when the uA and mA is measuring.

General maintenance

• To avoid electric shock or damage, before opening the housing or the battery cover, the connection of the test meter and the input signal must be removed.
• To clean the multi-meter housing, please use a piece of damp cloth and mild detergent to wipe it clean. Do not use abrasives or chemical solvents. Reading may be affected when input sockets are soiled or wet.

Technical data sheet
Comprehensive indicators

• Operating conditions:

  • 600V CAT II Pollution grade: 2
  • Height: under 2000m
  • Working temperature: 0-40℃（＜80%RH, not considered ＜10℃）
  • Storage temperature: -10-60℃（＜70%RH, take off battery）

• Test or calibrate surrounding temperature: 20℃±2℃

• The biggest voltage between measurement end and ground: 600V

• Fuse protection: mA range , fuse: F 600mA/250V
  A range, fuse: F10A/250V

• Conversion rate: about 3s/second

• Display:6000 counts LED display

• Overload: ‘OL’ displayed

• Low voltage display of battery: displayed when the working voltage is low

• Input polarity indicator: shown automatically

• Battery:3 X1.5V AAA

• Size: 147mm (L)71mm (W)45mm (H)

• Weight: about 220g (battery excluded)

Accuracy index

• Accuracy:± (%reading+digit）
  We provide one year warranty from the date of manufactured

• Conditions: surroundings temperature from 18℃to 28℃，＜80%RH

Direct current of voltage

• Input resistance: 10MΩ
• Maximum input voltage：600V

Alternative current of voltage True RMS

• input resistance: 10MΩ
• Maximum input voltage：600V
• Frequency response: 10HZ to1KHz TRMS

Resistance

• Overload protection:250V DC/AC
• Open circuit voltage: 2.4V

Diode and Buzzer

Overload protection: 250V DC/AC
Direct current DCA

Overload protection: mA range with F 200mA/250V and 20A range with F10A/250V
When the current is more than 5 A, the test time should be less than 10 minutes and one minute should be given to stop testing after such measurement.

Alternative current ACA

• Overload protection: mA range with F 600mA/250V and 20A range with F10A/250V
• Max input current: mA: 600mA RMS 10A:10A RMS
• When the current is more than 5 A, the test time should be less than ten minutes and one minute should be given to stop testing after such measurement.
• Frequency response: 10Hz to 1KHz true RMS

Frequency

• Input voltage range: 200mV-10V AC RMS
• Overload protection:250V DC/AC

Capacitance

• Overload protection:250V

Temperature

Operation instructions

Normal operation
Press the “FUNC/HZ” button and enter into function selection mode. The reading hold mode can keep the current reading on the display, change the measurement function position or press and hold the key again to exit the data hold mode.

Backlight and the torch function
The meter has a backlight and illumination function for reading the
measuring results in any lighting condition. To enter and exit this mode, please see below:

1. Short press the key to turn on the backlight and short press again to exit. It turns off automatically in 15 seconds when not in use.
2. Long press the key to turn on the illumination function and the backlight at the same time. Short press the key again to turn off the illumination function. It turns off automatically in 30 seconds when not in use.

Auto power off
If the multi-meter is not in use for 15 minutes after the power is switched on, it will give a voice prompt and shut off automatically. The power is now in hibernation mode, touching any key will re-activate the multi-meter again.

AC Voltage and DC Voltage measurement
To prevent electric shock or damage to the instrument, do not measure any voltage greater than 600V and do not apply more than 600V voltage between the common and earth.

AC Voltage and DC Voltage measuring

1. Turn the switch to or press “FUNC-Hz” to choose  AC or DC.
2. Connect the black test leads to the COM jack and the red leads to the jack.
3. Measure the voltage value of the circuit under test with the other two ends of the test leads.
4. The reading will be shown on the LED display as well as the polarity of the end connected with the red lead.

Notes:
*The meter shows readings in range DC Voltage 600mV and 6V even if there is no input voltage or test leads connection. Then short circuit and “COM” to make the meter shows zero.

• Please change to a higher range if the “OL” is shown.
• Under range AC Voltage, short pressing the “FUNC-Hz” key can test the  frequency of the alternating current power. Please refer to the frequency measurement
• The AC voltage values measured with this instrument are all true RMS values (square root). For sine waves and other waveforms (without DC offset) such as square waves, triangular waves and staircase waves, these measurements are accurate

Resistance measurement
To avoid damage to the meter or device under test, all power to the circuit under test should be cut off before measuring resistance, and all high-voltage capacitors should be fully discharged.

Resistance measuring:

1. Rotate the rotary switch to and press “FUNC-Hz” to chooseΩ。
2. Connect the black test leads to the “COM” input socket and the red test leads to “ ” input socket
3. Use the test leads to test the resistance value of the circuit.
4. The resistance value shows on the display window.

Notes:

• The resistance value measured on the circuit is usually different from the rate resistance.
• To measure the low resistance accurately, please short-circuit the two test leads to read out the short-circuit resistance of the test leads and subtract it from the readings to get an accurate resistance value.
• At 60 Mohms range, the reading will stabilize after a few seconds, which is normal for high resistance measurements.
• When the meter is not in the circuit, the display will show “OL”, indicating that the measurement value is out of the measurement range.

Diode measurement
To avoid damage to the meter or device under test, all power to the circuit under test should be cut off before measuring diode, and all high-voltage capacitors should be fully discharged.

Test a diode outside the circuit.：

1. Rotate the rotary switch to and press “FUNC-Hz” to choose
2. Connect the black test leads to the “COM” input socket and the red test leads to input socket
3. Touch the diode anode with the red probe, the black probe contacts the diode cathode.
4. The meter will display the forward bias value of the diode under test. If the polarity is reversed, then it shows ‘OL’.
5. The normal diode in the circuit still produces a forward voltage drop of 0.5V to 0.8V, but the reverse bias reading will depend on the variety of the resistance value of the other channels between the two test leads.

Continuity test
To avoid damage to the meter or device under test, all power to the circuit under test should be cut off before measuring on-off of the circuit and all high-voltage capacitors should be fully discharged.
For on-off state of the circuit:

1. Rotate the rotary switch to and press “FUNC-Hz” to choose
2. Connect the black test leads to the “COM” input socket and the red test leads to “ ” input socket
3. Measure the resistance of the circuit under test at the other end of the test leads. If the resistance of the circuit under test is not greater than about 50 ohms, the indicator light will turn on and the buzzer will sound continuously.

Frequency measurement
Do not test any voltage higher than 250V to prevent electric shock or damage to the instrument.

Frequency measuring:

1. Turn the switch to HZ%.
2. Connect the black test leads to the COM jack and the red leads to the  jack.
3. Measure the frequency value of the circuit under test with the other two ends of the test leads.
4. Press the “FUNC-Hz” button to show the readings of the frequency.

Current measurement
Do not attempt current measurement on the circuit when the voltage between the open circuit voltage and ground exceeds 250 volts. If the  fuse is blown during measurement, you may damage the meter or harm yourself. To avoid damage to the meter or test equipment, use the correct input socket, function gear, and range before making measurements before making measurements. When the test leads is plugged into the current input socket, do not connect the other end of the test leads in parallel to any circuit.

Current measurement:

1. Rotate the rotary switch to or and press “FUNC-Hz” to choose AC/DC.
2. Connect the black test leads to the “COM” input socket. If the measured current is less than 600mA, connect the red test leads to the “mA” input socket. If the measured current is between 600mA~10A, connect the red test lead to the “10A” input jack.
3. The circuit to be tested is disconnected, the black test leads is connected to the disconnected circuit, the lower voltage end thereof, and the red test leads is connected to the disconnected circuit at the higher voltage end.
4. Connect the circuit’s power supply and then read the displayed reading. If the display shows only “OL”, this indicates that the input exceeds the selected range. The rotary switch should be placed at a higher range.
5. Long press the “FUNC-Hz” to show the frequency of the alternative signal in the ACA mode.

Capacitance measurement
To avoid damage to the meter or device under test, all power to the circuit under test should be cut off before measuring capacitance. All high-voltage capacitors should be fully discharged.

Capacitance measuring:

1. Turn the rotary switch to position.
2. Connect the black test leads to the “COM” input socket and the red test leads to input socket
3. Measure the capacitance value of the circuit under test with the other two ends of the test leads. The reading will be shown on the LED display screen.

Notes:

• It needs a certain time to measure the big capacitor.
• Take note of the polarities of the capacitor to connect correctly to protect the meter.

NCV test
Rotate the rotary switch to the NCV position and place the top of the meter close to the conductor. If the meter detects the AC voltage meter, light the corresponding signal strength indicator according to the detected signal strength（low-yellow, high-red）, and the buzzer will send out different frequency alarms.

Notes:

1. Even if there is no indication that the voltage may still exist, do not rely on non-contact voltage detectors to determine if there is a voltage detection operation on the conductor, which may be affected by factors such as socket depth, insulation thickness, type, etc.
2. When the input voltage is input to the instrument, due to sensing in the presence of voltage, the voltage-sensing indicator light may light.
3. Interference sources in the external environment, such as flashlights, motors, etc., may accidentally trigger non-contact voltage detection.

Temperature measurement

1. Switch the rotate to “℃（℉）”.
2. Switching ℃or ℉by “FUNC/Hz”button
3. Insert the thermocouple into the instrument, the positive red is inserted into the input , and the negative black is inserted into the “COM” input.

Battery and fuse replacement
Replace batteries and fuses to avoid electric shock or personal injury caused by erroneous readings. When the symbol appears on the instrument display, replace the battery immediately. Use only the specified fuse, instant fuse. To avoid electric shock or personal injury, turn off the battery cover and replace it with a new one before turning it on. The test leads has been disconnected from the measurement circuit.

Please follow the steps below to replace the battery:

1. Turn off the power of the multi-meter.
2. Pull all the test leads out of the input sockets.
3. Use a screwdriver to loosen the screws that hold the battery cover.
4. Remove the battery cover.
5. Remove the old battery or the damaged fuse
6. Replace the new batteries or new fuses and tighten the screws.

Accessories

1. Instructions manual.
2. A pair of test leads.
3. A piece of the thermocouple.
4. Three AAA batteries.
5. 2 alligator clips.
6. 2 Safety tubes.

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