UNI-T UT39A+ 4000-Count True RMS Digital Multimeter: The Ultimate Guide

Overview

The UNI-T UT39A+ is a professional-grade, 4000-count digital multimeter that represents a significant upgrade in UNI-T's popular UT39 series . Designed with an innovative industrial aesthetic, this meter combines robust durability with comprehensive functionality, making it an indispensable tool for electricians, electronics enthusiasts, DIYers, and field service technicians .

Engineered to withstand the rigors of daily use, the UT39A+ features a remarkable 2-meter drop-proof design protected by a rugged, heavy-duty protective casing, ensuring it survives accidental falls that would destroy lesser meters . With safety ratings of CAT II 1000V and CAT III 600V, it delivers professional-grade protection in high-energy electrical environments .

The UT39A+ stands out with its 4000-count display, True RMS accuracy, and advanced features like NCV (Non-Contact Voltage) detection and transistor (hFE) testing—capabilities typically found in much more expensive meters .

Key Features at a Glance

• High Precision 4000-Count Display: 3 3/4 digit LCD with 56.5mm × 36mm large screen for clear readings 

• Exceptional Durability: 2-meter drop proof with rugged protective casing—ideal for job site use 

• Wide Measurement Range: Measures DC voltage up to 1000V and AC voltage up to 750V 

• High Current Capacity: Measures DC/AC current up to 20A 

• True RMS Technology: Provides accurate readings even with non-linear or distorted AC waveforms 

• Non-Contact Voltage (NCV) Detection: Safely detects live AC voltage without physical contact 

• Transistor (hFE) Testing: Built-in interface for testing transistor current gain 

• Capacitance Measurement: Measures capacitance up to 10mF (10,000μF) 

• Frequency Measurement: Up to 1MHz frequency testing capability 

• Fast Capacitance Response: Less than 6 seconds for measurements up to 10mF 

• User-Friendly Features: Auto-ranging, manual ranging, data hold, MAX/MIN recording, relative mode, and auto power off 

• Extended Battery Life: Low power consumption delivers up to 500 hours of operation 

• Safety Certified: CAT II 1000V / CAT III 600V with CE certification 

Detailed Specifications

The UNI-T UT39A+ delivers professional-grade accuracy across a comprehensive range of electrical parameters .

Electrical Measurement Specifications

Input Impedance: ≥10MΩ (DCV) 

General Characteristics

Special Functions

Mechanical & Environmental Specifications

What's in the Box

Key Functions & Operation

1. DC/AC Voltage Measurement

• Set the rotary switch to the voltage position

• Press SELECT to choose between AC and DC measurement

• Connect test leads in parallel to the circuit under test

• Measure up to 1000V DC or 750V AC with high accuracy 

2. DC/AC Current Measurement

• Set the rotary switch to the appropriate μA, mA, or A position based on expected current

• Press SELECT to choose AC or DC

• Connect test leads in series with the circuit

• The UT39A+ supports current measurement up to 20A 

• Dual fuse protection (0.2A fast-acting + 10A) prevents damage 

3. NCV (Non-Contact Voltage) Detection

• Set the rotary switch to the NCV position 

• Bring the top of the meter near a live conductor or outlet

• The meter provides audio and visual indication when AC voltage is detected 

• Safety Benefit: Allows quick verification of live circuits before physical contact

4. hFE Transistor Testing

• Set the rotary switch to the hFE position 

• Insert the transistor into the dedicated hFE socket, matching the correct pinout (E, B, C)

• Read the transistor's DC current gain (β) directly from the display

• Application: Essential for electronics work and component matching

5. Resistance Measurement

• Set the rotary switch to the Ω position

• Connect test leads across the resistor

• Measures resistance up to 200MΩ 

• For low resistance measurements, short test leads to check for zero reading

6. Continuity & Diode Testing

• Set the rotary switch to the continuity/diode position

• Press SELECT to cycle through functions

• Continuity: Buzzer sounds when resistance <10Ω, open >50Ω 

• Diode Test: Displays forward voltage drop with 2.2V open circuit voltage 

7. Capacitance Measurement

• Set the rotary switch to the capacitance position

• Fully discharge capacitors before testing to avoid damage

• Connect test leads in parallel with the capacitor

• Measures up to 10mF (10,000μF) 

• Fast Response: Less than 6 seconds for measurements up to 10mF 

• Use Relative Mode for accurate low-value capacitance measurements 

8. Frequency Measurement

• Set the rotary switch to the Hz position

• Connect test leads to the signal source

• Measure frequencies up to 1MHz 

9. MAX/MIN Recording

• Press MAX/MIN button to enter maximum/minimum measurement mode

• The meter records and displays the highest and lowest readings during the measurement period 

• Useful for monitoring fluctuating signals

10. Data Hold & Backlight

• Press HOLD to freeze the current reading on the display 

• Press and hold to turn the LCD backlight on/off 

• Backlit display ensures clear readings in low-light conditions 

11. Auto Power Off

• Meter automatically shuts down after approximately 15 minutes of inactivity to save battery 

• Press any button or turn the rotary switch to wake

Safety Features

The UT39A+ incorporates multiple advanced safety features to protect users:

• CAT II 1000V / CAT III 600V Rating: Suitable for measurements on distribution circuits and permanently installed equipment 

• 2-Meter Drop Proof: Withstands accidental falls from workbenches and ladders 

• Overload Protection: Comprehensive mis-test protection withstands surges up to 1kV 

• Fuse + PTC Protection: Dual protection system prevents damage from misconnection 

• Input Warning: Never apply voltage exceeding 1000V between terminals and ground 

• Low Battery Indication: Alerts user when batteries need replacement to maintain accuracy

UT39A+ vs. UT39C+ vs. UT39E+

The UT39+ series offers three distinct models with specialized features :

Applications

The UNI-T UT39A+ is an ideal tool for:

⚡ Electrical & Industrial Maintenance

• Troubleshooting control panels and machinery up to 1000V 

• Testing motor windings and contactors

• Measuring current on industrial equipment up to 20A 

• NCV detection for safe live wire identification 

🔧 Electronics Repair & Hobby

• Testing components on circuit boards with 4000-count precision 

• Measuring transistor gain (hFE) for matching pairs 

• Checking capacitor values up to 10mF 

• Diode and continuity testing for PCB troubleshooting

🏠 Residential Electrical Work

• Checking household outlet voltages (up to 750V AC) 

• Testing batteries and power adapters

• Troubleshooting lighting and appliance circuits

• Continuity checking for wiring and fuses

🚗 Automotive Diagnostics

• Testing car battery voltage (12V/24V systems)

• Checking alternator output

• Testing fuses and relays

• Verifying sensor operation

🎓 Educational & Vocational Training

• Ideal for electronics students

• Teaching fundamental measurement techniques

• Safe introduction to electrical measurements

• Auto-ranging simplifies learning for beginners 

Customer Reviews Summary

Users consistently praise the UT39A+ for:

• Build Quality: "Overall construction feels very premium... Feels sturdy in the hand" 

• Durability: 2-meter drop protection and protective casing inspire confidence on job sites 

• Value for Money: "Своих денег стоит однозначно" (Definitely worth its money) — Verified buyer 

• Accuracy: "非常好用，功能多，试了一下，测量还是很精准的" (Very easy to use, many functions, tested and found very accurate) 

• Features: NCV and hFE functions are frequently highlighted as key benefits 

Why Choose the UNI-T UT39A+?

The UT39A+ stands out as a professional-grade, feature-rich multimeter at an accessible price point.

Key Differentiators:

Final Verdict

The UNI-T UT39A+ is a versatile, durable, and feature-packed digital multimeter that delivers professional-grade performance without breaking the bank . With its 4000-count True RMS accuracy, 2-meter drop-proof design, NCV detection, hFE transistor testing, and 10mF capacitance measurement, it offers exceptional value for electricians, electronics enthusiasts, and DIYers alike