NJTY T28B Digital Multimeter User Manual

1. Introducció

The NJTY T28B is a high-precision digital multimeter designed for household and professional electrical measurements. It features True RMS measurement, a 6000-count display, and a wide range of functions including AC/DC voltage, AC/DC current, resistance, capacitance, frequency, temperature, diode, and continuity testing. This manual provides detailed instructions for safe and effective use of your multimeter.

Figure 1: NJTY T28B Digital Multimeter highlighting key features.

2. Informació de seguretat

Always observe safety precautions when using this multimeter to prevent electric shock or personal injury. Improper use can damage the instrument or connected equipment.

• Read and understand all instructions in this manual before use.
• No supereu els valors d'entrada màxims per a cap funció.
• Ensure the test leads are in good condition and properly connected for the measurement being performed.
• Do not use the meter if it appears damaged or if the casing està obert.
• Aneu amb compte quan treballeu amb volumtagper sobre de 30 V CA RMS, 42 V pic o 60 V CC, ja que representen un perill de descàrrega elèctrica.
• Desconnecteu sempre l'alimentació del circuit que s'està provant abans de connectar o desconnectar els cables de prova per a les mesures de corrent.
• Canvieu les piles quan aparegui l'indicador de bateria baixa per garantir lectures precises.
• The device is equipped with overload protection. However, avoid inputting voltage into current sockets to prevent damage.

3. Contingut del paquet

Verifiqueu que tots els elements siguin presents al vostre paquet:

• NJTY T28B Digital Multimeter
• Test Probes (Red and Black)
• Sonda de temperatura
• Manual d'usuari

Figure 2: Included accessories: Multimeter, Test Probes, Temperature Probe, and User Manual.

4. Producte acabatview

Familiarize yourself with the components of your NJTY T28B Multimeter:

Figure 3: Front panel and input jacks.

• Pantalla de visualització: Mostra lectures de mesurament i indicadors.
• Botó de funció: Rotary switch to select measurement functions (e.g., V, A, Ω, Hz, °C, NCV).
• FUNC/HOLD Button: Short press to switch between functions within a mode (e.g., AC/DC, Hz/Duty Cycle). Long press for Data Hold.
• Hz/%/Δ Button: For Frequency/Duty Cycle measurements.
• Botó RANGE: For manual range selection (Auto Range is default).
• Flashlight/Backlight Button: Activates the flashlight and display backlight.
• NCV Electric Field Induction Probe: For Non-Contact Voltage detecció.
• Preses d'entrada:
• mA/μA Jack: For small current measurements (up to 500mA FUSED).
• Jack de 20A: For large current measurements (up to 20A FUSED).
• COM Jack: Entrada comuna (negativa) per a totes les mesures.
• VΩHz°C Jack: Entrada positiva per a Voltage, Resistance, Frequency, Capacitance, Diode, Continuity, and Temperature measurements.

Figure 4: Multimeter with soft rubber casing per a protecció.

Figure 5: Multimeter with integrated kickstand for convenient viewing.

5. Configuració

5.1 Instal·lació de la bateria

The NJTY T28B Multimeter requires four 1.5V AAA batteries for operation. Batteries are not included.

1. Assegureu-vos que el multímetre estigui APAGAT.
2. Localitzeu el compartiment de la bateria a la part posterior del dispositiu.
3. Feu servir un tornavís per obrir la tapa del compartiment de la bateria.
4. Introduïu quatre piles AAA d'1.5 V, respectant la polaritat correcta (+/-) tal com s'indica a l'interior del compartiment.
5. Substituïu la tapa del compartiment de la bateria i fixeu-la amb el cargol.

Figure 6: Battery compartment requiring four 1.5V AAA batteries.

Figure 7: Correct battery insertion.

6. Instruccions de funcionament

Before any measurement, ensure the multimeter is set to the correct function and the test leads are connected to the appropriate input jacks.

6.1 General Measurement Steps

1. Turn the function knob to the desired measurement mode.
2. Connecteu el cable de prova negre a la presa COM.
3. Connect the red test lead to the appropriate positive input jack (VΩHz°C for voltage, resistance, etc., or mA/μA/20A for current).
4. Connecteu els cables de prova al circuit o component que s'està provant.
5. Llegiu el valor de mesura a la pantalla.

6.2 AC Voltage Mesura

1. Turn the function knob to the 'V~' (AC Voltage) posició.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Connect the test leads in parallel across the AC voltage font.
4. Llegeix l'AC voltage valor a la pantalla.

Figura 8: AC Voltage Measurement. Ensure correct jack usage.

6.3 DC Voltage Mesura

1. Turn the function knob to the 'V=' (DC Voltage) posició.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Connect the test leads in parallel across the DC voltage source, observing polarity.
4. Llegeix el vol DCtage valor a la pantalla.

Figura 9: DC Voltage Mesura.

6.4 Mesura de corrent (CA/CC)

WARNING: Current measurements must always be made in series with the circuit. Never connect the multimeter in parallel across a voltage source when in current mode, as this will cause a short circuit and damage the meter or power source.

1. Turn the function knob to the 'A~' (AC Current) or 'A=' (DC Current) position.
2. Determine the expected current range. For small currents, connect the red test lead to the mA/μA jack. For large currents (up to 20A), connect the red test lead to the 20A jack. The black test lead always goes to COM.
3. Open the circuit where you want to measure current and connect the multimeter in series.
4. Llegiu el valor actual a la pantalla.

Figure 10: Current Measurement. Note the series connection.

6.5 Mesura de la Resistència

1. Turn the function knob to the 'Ω' (Resistance) position.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Assegureu-vos que el circuit o component estigui desenergitzat abans de mesurar la resistència.
4. Connecteu els cables de prova a través del component.
5. Llegiu el valor de resistència a la pantalla.

Figura 11: Mesura de resistència.

6.6 Mesura de la capacitat

1. Turn the function knob to the 'Cx' (Capacitance) position.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Assegureu-vos que el condensador estigui completament descarregat abans de mesurar per evitar danys al mesurador.
4. Connecteu els cables de prova als terminals del condensador.
5. Read the capacitance value on the display. The meter can measure up to 100,000 μF.

Figure 12: Capacitance Measurement.

6.7 Mesura de freqüència/cicle de treball

1. Turn the function knob to the 'Hz/%' position.
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Connecteu els cables de prova a la font de senyal.
4. Press the 'Hz/%/Δ' button to toggle between Frequency (Hz) and Duty Cycle (%).
5. Llegeix el valor a la pantalla.

6.8 Mesura de la temperatura

1. Turn the function knob to the '°C/°F' (Temperature) position.
2. Connect the temperature probe to the VΩHz°C and COM jacks, observing polarity if applicable.
3. Place the tip of the temperature probe on or near the object whose temperature you wish to measure.
4. The display will show the temperature in Celsius (°C) or Fahrenheit (°F). Use the FUNC button to switch between units.

Figure 13: Temperature Measurement with switchable units.

6.9 Prova de díodes

1. Turn the function knob to the 'Diode' position (often shared with Continuity).
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Connecteu el cable de prova vermell a l'ànode i el cable de prova negre al càtode del díode.
4. La pantalla mostrarà el volum d'avançtage drop. Reverse the leads; the display should show 'OL' (Open Loop) for a good diode.

Figure 14: Diode Voltage Drop Measurement.

6.10 Prova de continuïtat

1. Turn the function knob to the 'Continuity' position (often shared with Diode).
2. Connect the black test lead to the COM jack and the red test lead to the VΩHz°C jack.
3. Connecteu els cables de prova a través del circuit o component.
4. If the resistance is below a certain threshold (typically 50Ω), the buzzer will sound, and the display will show a low resistance value.

Figure 15: Continuity Buzzer Measurement.

6.11 Vol. sense contactetage (NCV) Detecció

1. Turn the function knob to the 'NCV' position.
2. Hold the NCV Electric Field Induction Probe near a live AC voltage source (e.g., a wall outlet or live wire).
3. The meter will emit an audible beep and/or flash an indicator light, with the display showing 'NCV' and bars indicating signal strength, if AC voltages detecta e.

Figura 16: Volum sense contactetage (NCV) Detection.

6.12 característiques addicionals

• Conservació de dades: Press and hold the 'FUNC/HOLD' button to freeze the current reading on the display. Press again to release.
• Retroiluminació/Llanterna: Press the 'Flashlight/Backlight' button to turn on the display backlight or the integrated flashlight. Press again to cycle or turn off.
• Apagat automàtic: The multimeter will automatically power off after approximately 15 minutes of inactivity to conserve battery life.
• Volum baixtage Indicació: An icon will appear on the display when the battery voltage is low, indicating that batteries should be replaced soon.
• Magnetic Attraction Feature: The back of the multimeter has a magnetic strip for convenient attachment to metal surfaces.

7. Especificacions

The following table outlines the functional parameters and general specifications of the NJTY T28B Digital Multimeter:

Figure 17: Functional Parameters Table.

Figure 18: Device Dimensions.

8. Manteniment

8.1 Neteja

Netegeu el cas amb l'anunciamp drap i detergent suau. No utilitzeu abrasius ni dissolvents. Mantingueu els terminals d'entrada lliures de brutícia i humitat.

8.2 Substitució de la bateria

When the low battery indicator appears on the display, replace the batteries as described in the 'Setup' section (5.1 Battery Installation). Remove batteries if the meter is not used for an extended period.

8.3 Canvi de fusibles

If the current measurement function fails, the fuse may need replacement. Refer to the internal circuit board diagram for fuse locations. Always replace with a fuse of the specified type and rating (e.g., 500mA FUSED for mA/μA jack, 20A FUSED for 20A jack).

Figure 19: Internal circuit board for reference.

9. Solució De Problemes

• No Display/Meter won't turn on: Comproveu la instal·lació de les piles i assegureu-vos que no estiguin esgotades. Substituïu-les si cal.
• Es mostra 'OL' (sobrecàrrega): The measured value exceeds the selected range or the meter's maximum capability. Switch to a higher range (if in manual range mode) or ensure the input is within the meter's limits.
• Lectures incorrectes:
• Check if the function knob is set to the correct measurement type.
• Ensure test leads are properly connected to the correct input jacks.
• Verify that the test leads are not damaged.
• For resistance or capacitance, ensure the component is isolated from the circuit and fully discharged.
• La mesura de corrent no funciona: Check the fuse for the selected current jack (mA/μA or 20A). Replace if blown.
• Buzzer not sounding during continuity test: The resistance may be too high, or the circuit is open.

10. Consells d'usuari

• Probe Quality: Always ensure your test probes are in good condition and rated for the maximum voltage and current you intend to measure. The included probes are designed for the meter's specifications, including the 20A current range.
• Prevenció de danys: When measuring current, it is critical to connect the multimeter in series with the load. Never connect the current jacks directly across a voltage source (e.g., a battery or wall outlet) as this will immediately blow the fuse or damage the instrument.
• Descàrrega del condensador: For capacitance measurements, always discharge capacitors before connecting the multimeter to avoid potential damage to the meter or inaccurate readings.
• Auto Range Convenience: The T28B features auto-ranging, which simplifies operation by automatically selecting the correct measurement range. You can use the 'RANGE' button to switch to manual ranging if needed for specific applications.

11. Garantia i Suport

Per obtenir informació sobre la garantia o assistència tècnica, consulteu les polítiques del venedor o poseu-vos en contacte amb el punt de compra. Conserveu el rebut de compra com a comprovant de compra.