UNI-T UT71A Operating Manual
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UNI-T UT71A Operating Manual

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Model UT71A/B
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  • Page 1 Model UT71A/B OPERATING MANUAL...

  • Page 3: Table Of Contents

    Model UT71A/B: OPERATING MANUAL TABLE OF CONTENTS CHAPTER TITLE PAGE Before You Start Overview Unpacking Inspection Safety Information Rules For Safe Operation International Electrical Symbols Getting Acquainted Turning the Meter On Battery Considerations Automatic Power Off Automatic Backlight Off Low Battery Indication...
  • Page 4 Model UT71A/B: OPERATING MANUAL CHAPTER TITLE PAGE Analogue Bar Graph Using MAX MIN Making Measurements Introduction A. Measuring Voltages B. Measuring Currents C. Measuring Resistance D. Testing for Continuity E. Testing Diodes F. Measuring Capacitance G. Measuring Frequency / Duty Cycle H.
  • Page 5 Model UT71A/B: OPERATING MANUAL CHAPTER TITLE PAGE Changing the Default Setting Introduction Selecting Setup Options Maintenance A. General Service B. Replacing the Fuses C. Replacing the Battery Specifications Safety and Compliances Physical Specifications General Specifications Feature Summary Basic Specifications Detailed Accuracy Specifications A.
  • Page 6 Model UT71A/B: OPERATING MANUAL CHAPTER TITLE PAGE D. AC Current E. Resistance F. Continuity Test G. Diode Test H. Capacitance I. Frequency J. Temperature Degrees Celsius Fahrenheit K. 4~20mA loop current...

  • Page 7: Before You Start

    Meter. Digital Multimeter UT71A/B (hereafter referred to as “the Meter”) is a 20000 counts and 4 1/2 digits with steady operations, fashionable structure and auto ranging instrument. They all not only can measure AC voltage and current,...

  • Page 8: Unpacking Inspection

    Model UT71A/B: OPERATING MANUAL Unpacking Inspection Open the package case and take out the Meter. Check the items shown on Table 1-1 carefully to see any missing or damaged part: Table 1-1. Unpacking Inspection Item Description 1 piece English Operating Manual...

  • Page 9: Safety Information

    Model UT71A/B: OPERATING MANUAL Safety Information Rules For Safe Operation This Meter complies with the standards IEC61010 safety Warning measurement requirement: in pollution degree 2, To avoid possible electric shock or personal injury, overvoltage category (CAT. III 1000V, CAT.IV 600V) and to avoid possible damage to the Meter or to the and double insulation.
  • Page 10 Model UT71A/B: OPERATING MANUAL When the Meter working at an effective voltage over When servicing the Meter, use only the same model 60V in DC or 30V rms in AC, special care should be number or identical electrical specifications taken for there is danger of electric shock.

  • Page 11: International Electrical Symbols

    Model UT71A/B: OPERATING MANUAL International Electrical Symbols Symbols used on the Meter and in this manual are explained in Table1-2. Table 1-2. International Electrical Symbols AC or DC Measurement DC Measurement AC Measurement Grounding Double Insulated Warning. Refer to the Operating Manual...

  • Page 12: Getting Acquainted

    Model UT71A/B: OPERATING MANUAL Chapter 2 Getting Acquainted Turning the Meter On The automatic power off is preset to 10 minutes. From the Setup menu (see Chapter 5), you could specify a To turn the Meter on, turn the rotary switch from OFF time (10 minutes, 20 minutes, 30 minutes or OFF).

  • Page 13: Low Battery Indication

    Model UT71A/B: OPERATING MANUAL Low Battery Indication A constant battery icon ( ) in the upper left corner of the display notifies you that the batteries are low and should be replaced. Warning To avoid false readings, which could lead to possible...

  • Page 14: Rotary Switch

    Model UT71A/B: OPERATING MANUAL Rotary Switch Turn the Meter on by selecting any measurement function. The Meter presents a standard display for that function. The display may also be influenced by some of the choices made in Setup. Use the blue button to select any rotary switch alternate function (labeled in blue letters).
  • Page 15 Model UT71A/B: OPERATING MANUAL Table 2-1. Rotary Switch Selections Rotary Rotary Switch Function Blue Key Function Switch Position Resistance measurement Diode test Continuity test Capacitance measurement None Hz % Frequency measurement Frequency signal duty cycle measurement (UT71B only) ºC ºF...

  • Page 16: Functional Buttons

    Model UT71A/B: OPERATING MANUAL Functional Buttons The buttons activate features that augment the function selected with the rotary switch. The buttons are shown in Table 2-2. RECALL STORE Press the button once to access the main feature (e.g. STORE). To access the first additional feature of the button (e.g. RECALL), press and hold the button for over 1 second to access this additional feature.
  • Page 17 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Range feature: Press the button once. Exit AUTO and enter MANUAL ranging. In MANUAL, select SETUP next input range. EXIT to return to AUTO. AUTO is default. RANGE...
  • Page 18 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Setup feature: Press the button SEND In Setup, press to select OFF at the selection of HIGH and LOW once after entering Setup mode. (UT71A only) Store feature:...
  • Page 19 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Peak HOLD In Setup, each press to select the digit you want to edit. Press the button once after entering HOLD In Recall, press to enable SEND feature (UT71B only) Setup or Recall or Store mode.
  • Page 20 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Press to display max, min and average values. Press the button once. MAXMIN Press EXIT to stop and return to current measurement mode. (UT71A only) In Setup, each press to decrement an Option.
  • Page 21 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Press to enter relative mode, the primary display shows Press the button once. The left secondary display shows the present measurement value. The right secondary display shows the stored value.
  • Page 22 Model UT71A/B: OPERATING MANUAL Table 2-2. Functional Buttons Button Description Access Method Use the blue button to select any rotary switch alternate Press the button once function (labeled in blue letters). Press and hold the Button while turning on the Meter to Blue Button toggle to 2000 counts for all functions.

  • Page 23: The Meter Functions Vs Displays

    Model UT71A/B: OPERATING MANUAL The Meter Functions Vs Displays Table 2-3 shows the cross reference of function and display: Table 2-3 Functions Vs Displays Function Primary Display Right Secondary Display Left Secondary Display Full range: 2, 20, 200, 1000 The tested DC voltage value...
  • Page 24 Model UT71A/B: OPERATING MANUAL Table 2-3 Functions Vs Displays Function Primary Display Right Secondary Display Left Secondary Display Full range: 200, 2000 ACµA The tested ACµA value The tested frequency value: 40.00kHz~100.0kHz Full range: 20, 200 DCmA The tested DCmA value...
  • Page 25 Model UT71A/B: OPERATING MANUAL Table 2-3 Functions Vs Displays Function Primary Display Right Secondary Display Left Secondary Display The recalled value The total number of stored value. Index number: (UT71B only) no.0001~no.0100 Chapter 2 Getting Acquainted – Using MAX MIN...

  • Page 26: Selecting The Range

    Model UT71A/B: OPERATING MANUAL Selecting the Range Press RANGE to select either a fixed range or the autorange feature. Autoranging (AUTO lighted in the display) always comes on initially when you select a new function. In autorange, the Meter selects the lowest input range possible, ensuring that the reading appears with the highest available resolution.
  • Page 27 Model UT71A/B: OPERATING MANUAL Table 2-4. Display Features Symbol Meaning Maximum reading displayed. Minimum reading displayed Average reading displayed The sequence of the reading. ºC, ºF (UT71B only) Degrees Celsius (default) or Fahrenheit. HµmS H: Hour µ: Micro m: Minutes (Milli)
  • Page 28 Model UT71A/B: OPERATING MANUAL Table 2-4. Display Features Symbol Meaning TrueRMS Indicator for True RMS value. AC+DC For DCV and DCA functions, reading represents the True RMS total of AC and DC measurements , k , M : Ohm. The unit of resistance.
  • Page 29 Model UT71A/B: OPERATING MANUAL Table 2-4. Display Features Symbol Meaning nF,µF, Farad. The unit of capacitance nF: Nanofarad. 1x10 -9 or 0.000000001 farads. µF:Microfarad.1x10 -6 or 0.000001 farads. mF: Millifarad. 1x10 -3 or 0.001 farads. Automatic power off feature is on...
  • Page 30 Model UT71A/B: OPERATING MANUAL Table 2-4. Display Features Symbol Meaning Backlight feature is on HOLD Data hold mode is active PEAK HOLD Peak hold mode is active Diode test Frequency signal duty cycle. 4~20mA loop current as % reading The input value is too large for the selected range.

  • Page 31: Analogue Bar Graph

    Model UT71A/B: OPERATING MANUAL Analogue Bar Graph display. The minimum reading and MIN are shown on the right secondary display. The primary display shows The bar graph provides an analogue indication of the the maximum value. measured input. For most measurement functions, the bar graph updates 10 times per second.

  • Page 32: Making Measurements

    Model UT71A/B: OPERATING MANUAL Chapter 3 Making Measurement Introduction Chapter 3 explains how to make measurements. Most measurement functions can be selected by using the rotary switch. While letters or symbols identify primary functions; blue letters or symbols identify alternative functions. Press the BLUE button to access these alternate functions.
  • Page 33 ) impedance in black test lead into the COM terminal. parallel with the circuit. This loading effect can cause UT71A: Set the rotary switch to measurement errors in high impedance circuits. In UT71B: Set the rotary switch to most cases, the error is negligible (0.1% or less) if...

  • Page 34: Measuring Currents

    Model UT71A/B: OPERATING MANUAL B. Measuring Currents Warning If the fuse burns out during measurement, the Meter may be damaged or the operator himself may be hurt. To avoid possible damage to the Meter or to the equipment under test, check the Meter’s fuses before measuring current.
  • Page 35 Model UT71A/B: OPERATING MANUAL DC measurement is default, press blue button to Note select AC measurement. If the value to be measured is unknown, use the Open the circuit path to be tested. Touch the red maximum measurement position and reduce the testing leads to the more positive side of the break;...

  • Page 36: Measuring Resistance

    Model UT71A/B: OPERATING MANUAL C. Measuring Resistance Warning To avoid harms to you, please do not attempt to input voltage higher than 60V DC or 30V rms AC. To avoid possible damages to the Meter or to the devices under test, disconnect circuit power and discharge all the high-voltage capacitors before measuring resistance.

  • Page 37: Testing For Continuity

    Model UT71A/B: OPERATING MANUAL Note D. Testing for Continuity When measuring low resistance, the test leads can Warning add 0.1 to 0.2 of error to resistance measurement. To avoid harms to you, please do not attempt to input To test the leads, touch the probe tips together and voltage higher than 60V DC or 30V rms AC.
  • Page 38 Model UT71A/B: OPERATING MANUAL Note Open circuit voltage around –1.2V and range is 400 measurement range. When continuity testing has been completed, disconnect the connection between the testing leads and the circuit under test and remove the test leads away from the input terminals.

  • Page 39: Testing Diodes

    Model UT71A/B: OPERATING MANUAL E. Testing Diodes Warning To avoid harms to you, please do not attempt to input voltages higher than 60V DC or 30V rms AC. To avoid damages to the Meter or to the devices under test, disconnect circuit power and discharge all the high-voltage capacitors before testing diodes.
  • Page 40 Model UT71A/B: OPERATING MANUAL l When diode testing has been completed, disconnect For forward voltage drop readings on any semiconductor component, place the red test lead on the component’s the connection between the testing leads and the anode and place the black test lead on the component’s circuit under test and remove the test leads away cathode.

  • Page 41: Measuring Capacitance

    Model UT71A/B: OPERATING MANUAL F. Measuring Capacitance Warning To ensure accuracy, the Meter inside is discharged against the tested capacitor. “DIS.C” will be shown on the display when it is under discharging, this process will be quite slow. To avoid damage to the Meter or to the equipment...
  • Page 42 Model UT71A/B: OPERATING MANUAL l When capacitance measurement has been Set the rotary switch to measurement mode, the Meter may display a fixed reading which is a completed, disconnect the connection between the internal distributed capacitor value. For testing less...

  • Page 43: Measuring Frequency / Duty Cycle

    Model UT71A/B: OPERATING MANUAL G. Measuring Frequency / Duty Cycle Warning To avoid harms to you, please do not attempt to input voltage higher than 30V rms. To measure frequency and duty cycle, connect the Meter as Figure 3-7 and do the following: Insert the red test lead into the Hz terminal and the black test lead into the COM terminal.
  • Page 44 Model UT71A/B: OPERATING MANUAL Note The requirement of Input amplitude “a” is as follows: When 10Hz~40MHz: 200 mV 30Vrms; >40MHz: Un-specified When Hz measurement has been completed, disconnect the connection between the testing leads and the circuit under test and remove the test leads...

  • Page 45: Measuring Temperature

    Model UT71A/B: OPERATING MANUAL H. Measuring Temperature (UT71B only) Warning To avoid harms to you, please do not attempt to input voltages higher than 60V DC or 30V rms AC. To measure temperature, set up the Meter as shown in Figure 3-8 and proceed the following.

  • Page 46: 4~20Ma Loop Current As % Readout

    Model UT71A/B: OPERATING MANUAL Note The rest procedure, please follow B. Measuring Current: DC current measurement (Figure 3-2). Place the Meter in an environment of 18ºC~23ºC When the readings obtained is: otherwise false reading may be obtained especially < 4mA, the primary display shows LO in testing low temperature.

  • Page 47: Using Stores, Recall And Send Features

    Model UT71A/B: OPERATING MANUAL Chapter 4 Using Store, Recall & Send Features Introduction in second by pressing + or - button. The interval can be as high as 255 seconds or as low as 0 second. Chapter 4 shows you how to use stores, recall and Press and hold STORE to access the quick setting.

  • Page 48: Recalling Stored Readings

    Model UT71A/B: OPERATING MANUAL Recalling Stored Readings Using Send When using a Send feature, please refer to the Installation Use the following procedure to recall the stored reading: Guide of the included CD-ROM. Press RECALL to recall the stored value and RCL appears to confirm the operation.

  • Page 49: Changing The Default Setting

    Model UT71A/B: OPERATING MANUAL Chapter 5 Changing the Default Setting Introduction The Meter allows you to change the default operating configuration of the Meter by changing setup options made at the factory. These settings are stored and can be changed in the Setup mode using the procedure described in this chapter.
  • Page 50 Model UT71A/B: OPERATING MANUAL Table 5-1. Setup Selections Selection Option Factory Default Description HIGH Max. 40000; Press to select OFF Over the upper limits, beeps not continuously. Press to select the digit you want to edit Max. –40000; Press to select OFF Over the lower limits, beeps not continuously.
  • Page 51 Model UT71A/B: OPERATING MANUAL Table 5-1. Setup Selections Selection Option Factory Default Description Analogue Zero is in the left hand side. Zero is in the Zero is in the center center It can only apply to DCV, DCI and °C/°F functions.

  • Page 52: Maintenance

    Model UT71A/B: OPERATING MANUAL Chapter 6 Maintenance This chapter provides basic maintenance information including battery and fuse replacement instruction. Warning Do not attempt to repair or service your Meter unless you are qualified to do so and have the relevant calibration, performance test, and service information.

  • Page 53: Replacing The Fuses

    Model UT71A/B: OPERATING MANUAL B. Replacing the Fuses Warning To avoid electrical shock or arc blast, or personal injury or damage to the Meter, use specified fuses ONLY in accordance with the following procedure. Follow Figure 6-1 and proceed as follows to replace the Meter’s fuse:...

  • Page 54: Replacing The Battery

    Model UT71A/B: OPERATING MANUAL C. Replacing the Battery Warning To avoid false readings, which could lead to possible electric shock or personal injury, replace the battery as soon as the battery indicator “ ” appears. Make sure the test leads are disconnected from the circuit being tested before opening the case bottom.

  • Page 55: Specifications

    Model UT71A/B: OPERATING MANUAL Chapter 7 Specifications Safety and Compliances Refer to different range input protection voltage Maximum Voltage between any Terminal and Grounding Certification IEC 61010 CAT.III1000V, CAT.IV 600V overvoltage and double insulation standard Compliances 0.5A, 250V, fast type fuse, 5×20mm...

  • Page 56: Physical Specifications

    Model UT71A/B: OPERATING MANUAL Physical Specifications Digital: 20000 counts on primary display; updates 2-3 times / second. Display (LCD) 2000 counts on two secondary displays. Analog: 40 segments; updates 10 times / second. 0ºC~40ºC (32ºF~104ºF) Operating Temperature -10ºC~50ºC (14ºF~122ºF) Storage Temperature 75% @ 0ºC~30ºC below;...

  • Page 57: General Specifications

    Model UT71A/B: OPERATING MANUAL General Specifications Auto Range Auto Polarity Display OL Overloading (For UT71B only: except at 4~20mA Loop range which display HI or LO) Display Battery Deficiency...

  • Page 58: Feature Summary

    Model UT71A/B: OPERATING MANUAL Feature Summary Primary: 20,000 counts Tri Digital Displays Left Secondary: 2000 counts Right Secondary: 2000 counts Bar Graph: 40 segments, updates 10 times / second Analogue Bar Graph Bright backlight for clear readings in poorly lighted areas.

  • Page 59: Basic Specifications

    Model UT71A/B: OPERATING MANUAL Basic Specifications Function Ranges / Description 0 to 1000V DC Voltage 0 to 1000V, 100kHz bandwidth AC Voltage, True RMS DC Voltage: 0.025% Basic Accuracy AC Voltage: 0.4% 0 to 10A (5~10A for 10 seconds, interval 15 minutes)

  • Page 60: Detailed Accuracy Specifications

    Model UT71A/B: OPERATING MANUAL Detailed Accuracy Specifications Accuracy: ([% of reading] + [number of least significant digits), guarantee for 1 year. Operating temperature: 18ºC~28ºC Relative humidity: 75%RH A. DC Voltage Accuracy Range Resolution Overload Protection Input Impedance UT71A UT71B (0.05%+5) 200mV 0.01mV...

  • Page 61: Ac Voltage

    Model UT71A/B: OPERATING MANUAL B. AC Voltage (AC+DC measurement is available) Accuracy Input Impedance Range Resolution Bandwidth UT71A UT71B 0.0001V 45Hz~1kHz (0.8%+40) (0.6%+40) 1kHz~10kHz (1.8%+40) (1.6%+40) 10kHz~100kHz (7%+40) (7%+40) 0.001V 45Hz~1kHz (0.8%+40) (0.6%+40) 1kHz~10kHz (2%+40) (1.8%+40) 10kHz~100kHz (7%+40) (8%+40) Approx 10M 200V 0.01V...
  • Page 62 Model UT71A/B: OPERATING MANUAL Remarks: Overload Protection: 1000V. Display: a) True rms are valid from 10% of range to 100% of range b) AC crest factor can be up to 3.0 except 1000V where it is 1.5. c) A residual reading of 80 digits with test leads shorted, will not affect stated accuracy.

  • Page 63: Dc Current

    Model UT71A/B: OPERATING MANUAL C. DC Current Accuracy Range Resolution Overload Protection UT71A UT71B 200µA 0.01µA (0.2%+20) (0.15%+20) 2000µA 0.1µA 0.5A, 250V, fast type fuse, 5×20mm 20mA 0.001mA 200mA 0.01mA (0.8%+30) (0.7%+30) 0.001A 10A, 250V, fast type fuse, 5×20mm Remarks:...

  • Page 64: D. Ac Current

    Model UT71A/B: OPERATING MANUAL D. AC Current (AC+DC measurement is available) Accuracy Overload Protection Range Resolution Bandwidth UT71A UT71B 200µA 0.01µA 45Hz~1kHz (1%+15) (0.8%+15) 2000µA 0.1µA 1kHz~10kHz (2%+40) (1.5%+40) 0.5A, 250V, fast type 20mA 0.001mA fuse, 5×20mm 200mA 0.01mA 0.001A...

  • Page 65: E. Resistance

    Model UT71A/B: OPERATING MANUAL E. Resistance Accuracy Range Resolution Overload Protection UT71A UT71B (0.5%+20)+test leads 0.01 (0.4%+20)+test leads open circuit value open circuit value 0.0001k 1000V (0.5%+20) (0.4%+20) 0.001k 200k (1%+20) 0.01k (0.8%+20) (1%+40) 0.0001M (1%+40) (1.5%+40) 0.001M (1.5%+40) F. Continuity Test...

  • Page 66: G. Diode Test

    Model UT71A/B: OPERATING MANUAL G. Diode Test Range Resolution Overload Protection 0.0001V 1000V Remarks: Open circuit voltage approximate 2.8V. A good silicon junction drops between 0.5V and 0.8V. H. Capacitance Accuracy Range Resolution Overload Protection UT71A UT71B 20nF 0.001nF (1.2%+20)+ capacitance (1.5%+20)+ capacitance...

  • Page 67: Frequency

    Model UT71A/B: OPERATING MANUAL I. Frequency Range Resolution Accuracy Overload Protection 20Hz 0.001Hz 200Hz 0.01Hz 2kHz 0.0001kHz 20kHz 0.001kHz (0.1%+15) 1 0 0 0 V 200kHz 0.01kHz 2MHz 0.0001MHz 20MHz 0.001MHz 200MHz 0.01MHz Not Specified Remarks: l Input amplitude “a” as follows; (DC electric level is zero) When 10Hz~40MHz : 200mV 30Vrms;...

  • Page 68: Temperature

    Model UT71A/B: OPERATING MANUAL J. Temperature (UT71B only) Degrees Celsius Range Resolution Accuracy Overload Protection -40ºC~40ºC (3%+30) 1 0 0 0 V 40ºC~400ºC (1%+30) 0.1ºC 400ºC~1000ºC 2.5% Fahrenheit Range Resolution Accuracy Overload Protection -40ºF~32ºF (4%+50) 0.1ºF 1 0 0 0 V 32ºF~752ºF...

  • Page 69: 4~20Ma Loop Current

    Model UT71A/B: OPERATING MANUAL K. 4~20 mA loop current (UT71B only) Range Resolution Accuracy Overload Protection ( 4 ~ 2 0 m A ) % 0.01% (1%+50) 0.5A, 250V, fast type fuse, 5×20mm Remarks: When the readings obtained is: < 4mA, the primary display shows LO 4mA, the primary display shows 0% ….
  • Page 70 Model UT71A/B: OPERATING MANUAL This operating manual is subject to change without notice. Copyright 2005 Uni-Trend Group Limited. All rights reserved. Manufacturer: Uni-Trend Technology (Dongguan) Limited Dong Fang Da Dao Bei Shan Dong Fang Industrial Development District Hu Men Town, Dongguan City...

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