EMOS EM391 Digital Multimeter Instruction Manual

1. Introduction

This manual provides essential information for the safe and effective operation of your EMOS EM391 Digital Multimeter. Please read it thoroughly before use and retain it for future reference. The EMOS EM391 is designed for general electrical measurements, offering functions such as voltage, current, resistance, diode, and continuity testing.

2. Safety Information

Always observe the following safety precautions to prevent electric shock or personal injury, and to avoid damage to the multimeter or the equipment under test.

• Ensure the multimeter is set to the correct function and range before making any measurements.
• Do not apply more than the rated voltage, as marked on the multimeter, between the terminals or between any terminal and ground. This device is rated CAT III 300V.
• Use caution when working with voltages above 30V AC RMS, 42V peak, or 60V DC. These voltages pose a shock hazard.
• Always disconnect the test leads from the circuit before changing functions or ranges.
• Inspect the test leads for damaged insulation or exposed metal before use. Replace if damaged.
• Do not operate the multimeter if it appears damaged or if the case is open.
• Replace the battery as soon as the low battery indicator appears to ensure accurate readings.
• When servicing the multimeter, use only specified replacement parts.

3. Product Overview

The EMOS EM391 is a compact digital multimeter designed for various electrical measurements. It features a clear digital display, a rotary function switch, and input jacks for test leads.

Figure 1: EMOS EM391 Digital Multimeter with its included red and black test leads. The display shows '-1999', indicating a negative reading or an uninitialized state. The rotary switch is set to the 'OFF' position.

Components:

• LCD Display: Shows measurement readings, units, and indicators.
• Rotary Switch: Used to select measurement functions and ranges, and to power the device on/off.
• 'VΩmA' Input Jack: For voltage, resistance, diode, continuity, and current measurements up to 200mA.
• '10A' Input Jack: For high current measurements up to 10A.
• 'COM' Input Jack: Common (negative) input for all measurements.

4. Setup

4.1 Battery Installation

The EMOS EM391 Multimeter requires a 9V battery for operation. If the display does not light up or shows a low battery indicator, the battery needs to be replaced.

1. Ensure the multimeter is turned OFF and disconnect all test leads.
2. Locate the battery compartment cover on the back of the unit.
3. Unscrew the retaining screw(s) and carefully remove the cover.
4. Connect a new 9V battery to the battery clips, observing correct polarity.
5. Place the battery inside the compartment and replace the cover, securing it with the screw(s).

4.2 Connecting Test Leads

Proper connection of test leads is crucial for accurate and safe measurements.

1. Insert the black test lead into the 'COM' (common) input jack.
2. For most measurements (voltage, resistance, diode, continuity, and current up to 200mA), insert the red test lead into the 'VΩmA' input jack.
3. For high current measurements (up to 10A), insert the red test lead into the '10A' input jack. Always ensure the red lead is in the correct jack for the measurement type.

5. Operating Instructions

To begin, turn the rotary switch from 'OFF' to the desired measurement function and range.

5.1 Measuring DC Voltage (V=)

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the desired DC Voltage (V=) range (e.g., 200mV, 2V, 20V, 200V, 300V). If the voltage is unknown, start with the highest range and decrease as necessary.
3. Connect the test probes across the component or circuit to be measured, observing polarity.
4. Read the voltage value on the LCD display.

5.2 Measuring AC Voltage (V~)

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the desired AC Voltage (V~) range (e.g., 200V, 300V).
3. Connect the test probes across the AC voltage source.
4. Read the voltage value on the LCD display.

5.3 Measuring DC Current (A=)

Caution: Never connect the multimeter in parallel with a voltage source when measuring current, as this can blow the fuse or damage the meter.

1. For current up to 200mA: Connect the red test lead to the 'VΩmA' jack.
2. For current up to 10A: Connect the red test lead to the '10A' jack.
3. Connect the black test lead to the 'COM' jack.
4. Set the rotary switch to the desired DC Current (A=) range (e.g., 200µA, 2mA, 20mA, 200mA, 10A).
5. Open the circuit where current is to be measured and connect the multimeter in series with the load.
6. Read the current value on the LCD display.

5.4 Measuring Resistance (Ω)

Caution: Ensure the circuit is de-energized and all capacitors are discharged before measuring resistance.

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the desired Resistance (Ω) range (e.g., 200Ω, 2kΩ, 20kΩ, 200kΩ, 2MΩ).
3. Connect the test probes across the resistor or component to be measured.
4. Read the resistance value on the LCD display.

5.5 Diode Test

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the Diode Test symbol (→|).
3. Connect the red probe to the anode and the black probe to the cathode of the diode. The display will show the forward voltage drop.
4. Reverse the probes. The display should show 'OL' (Open Loop) for a good diode.

5.6 Continuity Test

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the Continuity Test symbol ()))).
3. Connect the test probes across the circuit or component.
4. If the resistance is below approximately 50Ω (this value can vary), the built-in beeper will sound, indicating continuity. The display will also show the resistance value.

5.7 Battery Test (1.5V/9V)

This function allows for a quick check of 1.5V and 9V batteries under a light load.

1. Connect the red test lead to the 'VΩmA' jack and the black test lead to the 'COM' jack.
2. Set the rotary switch to the '1.5V/9V' battery test position.
3. Connect the red probe to the positive terminal and the black probe to the negative terminal of the battery.
4. Read the voltage value on the LCD display. A significantly lower voltage than the nominal value indicates a weak or discharged battery.

6. Maintenance

6.1 Battery Replacement

Refer to Section 4.1 for detailed instructions on battery replacement. Always use a fresh 9V battery.

6.2 Fuse Replacement

If the current measurement function stops working, the fuse may need replacement. The 10A input is protected by a fuse.

1. Ensure the multimeter is turned OFF and all test leads are disconnected.
2. Open the battery compartment cover as described in Section 4.1. The fuse is typically located near the battery.
3. Carefully remove the old fuse.
4. Replace it with a fuse of the exact same type and rating: FUSED 10A Max.
5. Securely close the battery compartment cover.

6.3 Cleaning and Storage

Wipe the case with a damp cloth and mild detergent. Do not use abrasives or solvents. Store the multimeter in a cool, dry place. If storing for extended periods, remove the battery to prevent leakage.

7. Troubleshooting

8. Specifications

The following specifications are typical for the EMOS EM391 Digital Multimeter:

• Model Number: EM391
• Manufacturer: EMOS
• Measurement Type: Multimeter
• Power Source: 9V Battery (not included)
• Item Weight: 240 Grams
• Parcel Dimensions: 20.2 x 12.7 x 3.6 cm
• Min. Operating Voltage: 200 Millivolts
• Upper Temperature Rating: 20 Degrees Celsius
• Safety Rating: CAT III 300V
• DC Voltage Ranges: 200mV, 2V, 20V, 200V, 300V
• AC Voltage Ranges: 200V, 300V
• DC Current Ranges: 200µA, 2mA, 20mA, 200mA, 10A
• Resistance Ranges: 200Ω, 2kΩ, 20kΩ, 200kΩ, 2MΩ
• Diode Test: Yes
• Continuity Test: Yes (with beeper)
• Battery Test: 1.5V, 9V

Figure 2: Back of the EMOS EM391 Multimeter packaging, displaying various specifications and compliance marks in multiple languages.

9. Warranty and Support

EMOS products are manufactured to high-quality standards. For warranty information or technical support, please refer to the warranty card included with your product or contact EMOS customer service directly. Keep your purchase receipt as proof of purchase.

Manufacturer: EMOS

For further assistance, please visit the official EMOS website or contact your local distributor.