Extech Instruments 420 User Manual Download | Manualshive

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User's Guide

Digital Multimeter

Extech 420

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Summary of Contents for 420

Page 1: ...User s Guide Digital Multimeter Extech 420 ...

Page 2: ...l indicates the user must refer to the manual for further information This symbol adjacent to a terminal indicates that under normal use hazardous voltages may be present Double insulation This WARNING symbol indicates a potentially hazardous situation which if not avoided could result in death or serious injury This CAUTION symbol indicates a potentially hazardous situation which if not avoided m...

Page 3: ...cks on electrical outlets can be difficult and misleading because of the uncertainty of connection to the recessed electrical contacts Other means should be used to ensure that the terminals are not live If the equipment is used in a manner not specified by the manufacturer the protection provided by the equipment may be impaired This device is not a toy and must not reach children s hands It cont...

Page 4: ...V AC 200Vrms on 400mV range mAAC DC 500mA 250V fast acting fuse AAC DC 20A 250V fast acting fuse 30 seconds max every 15 minutes Frequency Resistance Capacitance Duty Cycle Diode Test Continuity 250Vrms for 15sec max Temperature 60V DC 24V AC 2 USE EXTREME CAUTION when working with high voltages 3 DO NOT measure voltage if the voltage on the COM input jack exceeds 600V above earth ground 4 NEVER c...

Page 5: ...e Tilt stand and battery compartment are on rear of unit Symbols and Annunciators Continuity Diode test Battery status Test lead connection error n nano 10 9 capacitance µ micro 10 6 amps cap m milli 10 3 volts amps A Amps k kilo 103 ohms F Farads capacitance M mega 10 6 ohms Ohms Hz Hertz frequency V Volts Percent duty ratio REL Relative AC Alternating current AUTO Autoranging DC Direct current H...

Page 6: ...his is normal and is caused by the high input sensitivity The reading will stabilize and give a proper measurement when connected to a circuit DC VOLTAGE MEASUREMENTS CAUTION Do not measure DC voltages if a motor on the circuit is being switched ON or OFF Large voltage surges may occur that can damage the meter 1 Set the function switch to the green V position 2 Press the SELECT button to indicate...

Page 7: ... side of the circuit 5 Read the voltage in the display DC CURRENT MEASUREMENTS CAUTION Do not make current measurements on the 20A scale for longer than 30 seconds Exceeding 30 seconds may cause damage to the meter and or the test leads 1 Insert the black test lead banana plug into the negative COM jack 2 For current measurements up to 4000µA DC set the function switch to the yellow µA position an...

Page 8: ... Remove power from the circuit under test then open up the circuit at the point where you wish to measure current 7 Touch the black test probe tip to the negative side of the circuit Touch the red test probe tip to the positive side of the circuit 8 Apply power to the circuit 9 Read the current in the display RESISTANCE MEASUREMENTS WARNING To avoid electric shock disconnect power to the unit unde...

Page 9: ...you wish to check 5 If the resistance is less than approximately 150 the audible signal will sound If the circuit is open the display will indicate OL DIODE TEST 1 Set the function switch to the green position 2 Insert the black test lead banana plug into the negative COM jack and the red test lead banana plug into the positive diode jack 3 Press the SELECT button to indicate on the display 4 Touc...

Page 10: ...ed 4 Read the capacitance value in the display FREQUENCY MEASUREMENTS 1 Set the rotary function switch to the green Hz position 2 Insert the black lead banana plug into the negative COM jack and the red test lead banana plug into the positive Hz jack 3 Touch the test probe tips to the circuit under test 4 Read the frequency on the display DUTY CYCLE 1 Set the rotary function switch to the Hz posit...

Page 11: ... the correct polarity 3 Touch the Temperature Probe head to the part whose temperature you wish to measure Keep the probe touching the part under test until the reading stabilizes about 30 seconds 4 Read the temperature in the display Note The temperature probe is fitted with a type K mini connector A mini connector to banana connector adaptor is supplied for connection to the input banana jacks ...

Page 12: ... 1 Perform the measurement as described in the operating instructions 2 Press the REL button to store the reading in the display and the REL indicator will appear on the display 3 The display will now indicate the difference between the stored value and the measured value 4 Press the REL button to exit the relative mode Note The Relative function does not operate in the Frequency function DISPLAY ...

Page 13: ...its 4000 A 1 A 40mA 0 01mA 400mA 0 1mA 4A 0 001A 2 5 reading 5 digits 20A 0 01A AC Current 50 to 400Hz 400Hz to 1KHz 400 A 0 1 A 1 8 reading 8 digits 3 0 reading 7 digits 4000 A 1 A 40mA 0 01mA 400mA 0 1mA 4A 0 001A 3 0 reading 8 digits 3 5 reading 10 digits 20A 0 01A Resistance 400 0 1 0 8 reading 4 digits 4k 0 001k 0 8 reading 2 digits 40k 0 01k 1 0 reading 2 digits 400k 0 1k 4M 0 001M 40M 0 01M...

Page 14: ...t 0 7mA Temperature Sensor Requires type K thermocouple Input Impedance 7 5MΩ VDC VAC AC Response Average responding ACV Bandwidth 50Hz to 1kHz Display 4000 count backlit liquid crystal Overrange indication OL is displayed Auto Power Off 15 minutes approximately Polarity Automatic no indication for positive Minus sign for negative Measurement Rate 2 times per second nominal Low Battery Indication ...

Page 15: ...d or weak batteries so they do not leak and damage the unit 6 IF THE METER IS TO BE STORED FOR A LONG PERIOD OF TIME the batteries should be removed to prevent damage to the unit Battery Replacement 1 Remove the Phillips head screw that secures the rear battery door 2 Open the battery compartment 3 Replace the 9V battery 4 Secure the battery compartment You as the end user are legally bound Batter...

Page 16: ...er circuit board straight up from the connectors to gain access to the fuse holders 6 Gently remove the old fuse and install the new fuse into the holder 7 Always use a fuse of the proper size and value 0 5A 250V fast blow for the 400mA range 20A 250V fast blow for the 20A range 8 Align the center board with the connectors and gently press into place 9 Replace and secure the rear cover battery and...

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