This manual introduces the functions and usage of Extech 420 (part number EX420) Autoranging Multimeter. This meter measures AC/DC Voltage, AC/DC Current, Resistance, Capacitance, Frequency, Duty Cycle, Diode Test, and Continuity plus Thermocouple Temperature. Proper use and care of this meter will provide many years of reliable service.
The Extech 420 is an autoranging digital multimeter designed to measure AC/DC voltage, AC/DC current, resistance, capacitance, frequency, duty cycle, diode test, continuity, and thermocouple temperature. The device features a 4000 count LCD display with annunciators for various functions such as battery status and test lead connection errors.
The manual details safety precautions, including input protection limits (1000V DC / 750V AC), overvoltage category III compliance, and warnings regarding high voltage circuits. It provides step-by-step instructions for operating the function switch, connecting test leads to appropriate jacks (COM, V, mA/uA/A, 20A), and performing measurements while observing specific cautions for current ranges and capacitor discharge.
| Display Count | 4000 count LCD display |
|---|---|
| Overvoltage Category | Category III |
| Max Input Voltage DC/AC | 1000V DC / 750V AC |
| DC Current Range (20A) | 20A DC |
| AC Current Range (20A) | 20A AC |
The meter measures AC/DC Voltage, AC/DC Current, Resistance, Capacitance, Frequency, Duty Cycle, Diode Test, and Continuity plus Thermocouple Temperature.
The maximum input limit is 1000V DC or 750V AC.
Do not make current measurements on the 20A scale for longer than 30 seconds.
If the resistance is less than approximately 150 Ω, an audible signal will sound.