KEYSIGHT U1242C Handheld Digital Multimeter User Manual

1. Introduction

The KEYSIGHT U1242C is a robust and reliable handheld digital multimeter (DMM) designed for professional and industrial use. It offers high accuracy, durability, and advanced features for various electrical measurements. This manual provides essential information for the safe and efficient operation, maintenance, and troubleshooting of your U1242C DMM.

Key features include:

• 50,000 counts resolution on dual display
• 0.03% basic DC voltage accuracy
• True RMS AC measurement
• Data logging to DMM (max. 200 points) & PC with software bundle
• IP 67 certified for dust and water resistance
• Withstands up to 3-meter (10 feet) drop
• Built-in LED flashlight

2. Safety Information

WARNING: Read and understand all safety instructions before operating this device. Failure to follow these instructions may result in injury or damage to the meter.

• This product is intended for professional use only.
• Always adhere to local and national safety codes.
• Do not use the meter if it appears damaged or if the insulation is compromised.
• Ensure test leads are in good condition and properly connected before making measurements.
• Do not exceed the maximum input limits for any function.
• Use caution when working with voltages above 30V AC RMS, 42V peak, or 60V DC. These voltages pose a shock hazard.
• Always turn off the circuit power and discharge all high-voltage capacitors before performing resistance, continuity, or diode tests.
• Replace the battery and fuses only with the specified type and rating.

3. Product Overview

3.1 Front View

This image displays the front of the KEYSIGHT U1242C Digital Multimeter, showing its large orange casing, the dual display screen, the rotary dial for function selection, and the input jacks for test leads. Various buttons for functions like Max/Min, Hz, Log, Hold, and Range are visible around the display.

3.2 Side View

This image shows the side profile of the KEYSIGHT U1242C Digital Multimeter, highlighting its ergonomic design and the textured grip on the orange casing. The side view emphasizes the compact and robust build of the device.

3.3 Back View

This image presents the back of the KEYSIGHT U1242C Digital Multimeter, revealing the battery compartment cover, the kickstand for hands-free operation, and the product label with model and serial number information. The robust construction of the casing is also evident.

3.4 Controls and Connectors

• Display: Large dual display for primary and secondary readings.
• Rotary Switch: Selects measurement functions (Voltage, Current, Resistance, etc.).
• Function Buttons: Max/Min, Hz, Log, Hold, Range, View, Shift.
• Input Jacks:
• VΩHz: Input for voltage, resistance, frequency, capacitance, and diode tests.
• COM: Common input for all measurements.
• mAµA: Input for milliampere and microampere current measurements.
• 10A MAX FUSED: Input for high current measurements (up to 10A).

4. Setup

4.1 Battery Installation

1. Ensure the multimeter is turned OFF.
2. Locate the battery compartment on the back of the meter.
3. Use a screwdriver to loosen the screw securing the battery cover.
4. Remove the battery cover.
5. Insert the specified batteries (e.g., 4 x AAA batteries) observing the correct polarity (+/-).
6. Replace the battery cover and tighten the screw securely.

4.2 Test Lead Connection

Always connect the test leads to the appropriate input jacks for the measurement you intend to perform. Incorrect connection can lead to damage to the meter or personal injury.

• For most measurements (Voltage, Resistance, Continuity, Diode, Capacitance, Frequency), connect the black test lead to the COM jack and the red test lead to the VΩHz jack.
• For current measurements (mA/µA), connect the black test lead to the COM jack and the red test lead to the mAµA jack.
• For high current measurements (up to 10A), connect the black test lead to the COM jack and the red test lead to the 10A MAX FUSED jack.

5. Operating Instructions

This section outlines the basic steps for performing common measurements with your U1242C DMM.

5.1 Measuring AC/DC Voltage

1. Turn the rotary switch to the desired voltage range (V~ for AC, V- for DC). The meter may have an auto-ranging feature.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz jack.
3. Connect the test probes in parallel across the circuit or component to be measured.
4. Read the voltage value on the display.

5.2 Measuring AC/DC Current

CAUTION: Never connect the meter in parallel with a voltage source when measuring current. This can blow the fuse or damage the meter.

1. Turn the rotary switch to the desired current range (A~ for AC, A- for DC, or mA/µA ranges).
2. Connect the black test lead to the COM jack.
3. For mA/µA measurements, connect the red test lead to the mAµA jack. For 10A measurements, connect the red test lead to the 10A MAX FUSED jack.
4. Open the circuit where current is to be measured and connect the meter in series with the circuit.
5. Read the current value on the display.

5.3 Measuring Resistance

1. Turn the rotary switch to the Ω (Ohms) range.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz jack.
3. Ensure the circuit or component is de-energized before measuring resistance.
4. Connect the test probes across the component to be measured.
5. Read the resistance value on the display.

5.4 Continuity Test

1. Turn the rotary switch to the continuity symbol (speaker icon).
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz jack.
3. Ensure the circuit is de-energized.
4. Connect the test probes across the circuit or component.
5. The meter will beep if continuity is detected (resistance below a certain threshold).

5.5 Data Logging

The U1242C supports data logging. Refer to the detailed user manual for specific instructions on activating and managing data logging functions, including connecting to a PC with the software bundle for extended logging capabilities.

6. Maintenance

6.1 Cleaning

Wipe the meter's casing with a damp cloth and mild detergent. Do not use abrasives or solvents. Ensure the meter is completely dry before use.

6.2 Battery Replacement

When the battery indicator appears on the display, replace the batteries as described in Section 4.1. Prompt battery replacement ensures accurate readings and proper operation.

6.3 Fuse Replacement

WARNING: Always replace blown fuses with fuses of the exact same type and rating to maintain safety and performance.

1. Ensure the multimeter is turned OFF and all test leads are disconnected.
2. Open the battery compartment as described in Section 4.1.
3. Locate the fuse(s) inside the compartment.
4. Gently remove the blown fuse.
5. Insert a new fuse of the correct rating (e.g., 10A/1000V for the 10A input).
6. Replace the battery cover and tighten the screw securely.

6.4 Calibration

The U1242C is factory calibrated. For continued accuracy, periodic calibration by a qualified service center is recommended. Refer to KEYSIGHT's official support channels for calibration services.

7. Troubleshooting

8. Specifications

9. Warranty and Support

9.1 Legal Disclaimer

Keysight Technologies products are classified as industrial monitoring and control equipment designed exclusively for professional or industrial use and related training programs. Keysight products are designed and certified to meet national industrial safety standards (such as Electrical Equipment for Measurement, Control and Laboratory Use) where products are sold solely for use by trained professionals. Keysight products are not intended for consumer use in a residential setting and may not meet consumer level standards for EMC and other regulated radiated emissions. Keysight products are intended for use in the country where the product was originally sold.

9.2 Technical Support

For technical assistance, service, or warranty claims, please contact KEYSIGHT customer support through their official website or authorized service centers. Provide your product model number (U1242C) and serial number when seeking support.