CEN-TECH 98025 Seven Function Digital Multimeter Manual

CEN-TECH 98025 Seven Function Digital Multimeter

General Safety Rules

Electrical shock can cause death or injury! NEVER TOUCH exposed conductors of electricity.
Inspect the Multimeter before use. In 2. addition to a general inspection, look specifically for:
- Pay special attention to the insulation protecting the connectors.
- Check the leads for exposed metal, b. damaged insulation, and continuity.
- Replace damaged test lead immediately, before use.
This meter should be powered only by 4. a single, correctly installed 9V battery.
Use caution when working near volt5. ages above 30 VAC RMS, 42 VAC peak, or 60 VDC. Voltages this high present a risk of electric shock.
Disconnect the circuit’s power before 6. connecting the meter in series, when measuring current.
Connect the common (COM) test lead 7. first and disconnect it last.
Hold the probes with fingers behind 8. guards.
Avoid electrical shock. Use 9. extreme caution when working near uninsulated conductors or bus bars. Prevent body contact with grounded surfaces such as pipes, radiators, ranges, and cabinet enclosures when testing voltages.
Observe work area conditions. Do not 10. test voltages in damp locations. Don’t be exposed to rain. Keep the work area clean and well-lit.
Keep children away. Children must 11. never be allowed in the work area.
Stay alert. Watch what you are doing, 12. use common sense. Do not operate any meter when you are tired.
Do not operate the meter if under the 13. influence of alcohol or drugs. Read warning labels on prescriptions to determine if your judgment or reflexes are impaired while taking drugs. If there is any doubt, do not operate the meter.
Due to the danger inherent in such 14. work, we strongly recommend that only a licensed electrician work on high-voltage or other potentially dangerous circuits.
Do not test voltage on circuits higher than 16. than 750 volts AC or 1000 volts DC. This type of testing should only be done by a qualified electrician.
Do not test current on circuits higher than 17. than 200 mA.
Store idle equipment. When not in 18. use, meters must be stored in a dry location to decrease exposure to moisture. Lock up meters and keep them out of reach of children.
Dress properly. Protective, electrically 19. nonconductive clothes and nonskid footwear are recommended when working.
Avoid damaging the meter. Use only as 23. specified in this manual.
Before testing, resistance, diodes, or 24. continuity; disconnect all power to the circuit and discharge all high voltage capacitors.
Performance of this meter may vary 25. depending on the battery condition.

Specifications

Unpacking

When unpacking, check to make sure that the item is intact and undamaged. If any parts are missing or broken, please call Harbor Freight Tools at the number shown on the cover of this manual as soon as possible.

Operating Instructions

Do not test voltage on AC circuits higher than 750 volts. Do not test voltage on DC circuits higher than 1000 volts. Do not test current on circuits higher than 10 amps.

Disconnect Test Leads. Use a 1. screwdriver to remove both screws on the rear of the unit. Observe polarity, and attach a 9V battery to the posts. Replace and secure the cover.
Do not apply voltage to the Test 2. Leads, when they are connected to the COM (Bottom) and VWmA (Center) Jacks and the Multimeter, are in an Ohms testing setting. Damage can occur to the multimeter or the fuse may blow.
Do not switch between testing modes 3. with the multimeter connected to a circuit.

AC Voltage Measurements

Measure AC conductors carrying up 1. to 750 VAC, 45-450 Hz.
Turn the Range Selector Switch to 2. 750 ACV setting. Always start with the highest range if the voltage is unknown.
Plug the red lead into the VWmA 3. (Center) Jack. Plug the black lead into the COM (Bottom) Jack. Switch the Multimeter ON.
Carefully touch the exposed conductors with the tips of the probes to measure the voltage (not amperes).
Read measurement.
If the voltage is less than 200 volts, Set the Range Selector Switch to the lower range.
When testing is complete, remove
Test Leads and store them with a multimeter.

DC Voltage Measurements

Measure DC conductors carrying up to 1000 VDC.
Turn the Range Selector Switch to a 1000 DCV setting.
Follow the directions above under 3. “AC Voltage Measurements”, only use the DC settings instead.

DC Current Measurements

Measure DC conductors carrying up to 10 amperes.
Turn the Range Selector Switch to the 10A position.
Always start with the highest range if the amperage is unknown.
Plug the red lead into the 10A (Top) 4. Jack. Plug the black lead into the COM (Bottom) Jack. Switch the Multimeter ON.
Carefully touch the exposed conductors with the tips of the probes to measure the amperage.
Read measurement. 6.
If the reading is less than .2 AMPs, Switch the red lead to the VWmA (Center) Jack and set the Range Selector Switch to the 200 mA setting.
When testing is complete, remove 8. Test Leads and store them with a multimeter.

Resistance Measurements

Measure circuit resistance up to 2000K Ohms.
Warning: Never measure resistance 2. on a circuit with voltage running through it.
Turn the Range Selector Switch to the 3. 200 W position.
Plug the red Test Lead into the VWmA 4. (Center) Jack. Plug the black Test Lead into the Com (Bottom) Jack. Switch the Multimeter ON.
Short the Test Leads together. The 5. meter should read “0” Ohms.
Touch the exposed conductors with 6. the tips of the Test Leads.
Read measurement.7.
If the reading is “1”, set the Range 8. Selector Switch to the next higher Ohm (W) position.

Transistor (hFE ) Measurements

Test transistors to ensure proper function.
Turn the Range Selector Switch to the 2. hFE position.
Switch the Multimeter ON.
Insert the transistor pins into the 4. appropriate hFE jack (NPN or PNP) according to the EBC (Emitter, Base, Collector) sequence.
The meter will show the approximate hFE value.

Diode Measurement

Test the voltage drop in diodes.
Turn the Range Selector Switch to the Diode position.
Plug the red Test Lead into the VWmA (Center) Jack. Plug the black Test Lead into the Com (Bottom) Jack. Switch the Multimeter ON.
Connect the red probe to the anode of the diode and the black to the cathode.
The approximate forward voltage drop of the diode will be displayed in mV. If the connection is reversed only “1” will be shown.

Battery Charge Measurement

Test the amount of charge left in batteries.
Turn the Range Selector Switch to the Battery position.
Plug the red Test Lead into the VWmA (Center) Jack. Plug the black Test Lead into the Com (Bottom) Jack. Switch the Multimeter ON.
Connect the red probe to the positive terminal of the battery and the black to the negative terminal.
The battery amperage under a load of 370 mW will be displayed to a resolution of .1 mA.
Normal amperage: For a standard 9V (6LR61) battery = 25 mA
For a 1.5 V “AA” (LR6) battery = 4 mA
To prevent accidents, turn off the tool and disconnect its power supply after use. Clean, then store the tool indoors out of children’s reach. User- Maintenance Instructions.

Cleaning, Maintenance, and Lubrication

BEFORE EACH USE, inspect the general condition of the tool. Check for loose screws, misalignment or binding of moving parts, cracked or broken parts, damaged electrical wiring, and any other condition that may affect its safe operation.
After Use, clean the external surfaces of the tool with a clean cloth.
Replace the battery as necessary.
No replaceable parts.

LIMITED 90 DA Y WARRANTY

Harbor Freight Tools Co. makes every effort to assure that its products meet high quality and durability standards, and warrants to the original purchaser that this product is free from defects in materials and workmanship for 90 days from the date of purchase.

This warranty does not apply to damage due directly or indirectly, to misuse, abuse, negligence or accidents, repairs or alterations outside our facilities, criminal activity, improper installation, normal wear and tear, or to lack of maintenance.

We shall in no event be liable for death, injuries to persons or property, or for incidental, contingent, special, or consequential damages arising from the use of our product. Some states do not allow the exclusion or limitation of incidental or consequential damages, so the above limitation or exclusion may not apply to you.

To take advantage of this warranty, the product or part must be returned to us with transportation charges prepaid. Proof of purchase date and an explanation of the complaint must accompany the merchandise. If our inspection verifies the defect, we will either repair or replace the product at our election or we may elect to refund the purchase price if we cannot readily and quickly provide you with a replacement.

We will return repaired products at our expense, but if we determine there is no defect, or that the defect resulted from causes not within the scope of our warranty, then you must bear the cost of returning the product. This warranty gives you specific legal rights and you may also have other rights which vary from state to state.

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CEN-TECH 98025 Seven Function Digital Multimeter-FAQs

How does a smart multimeter work?

A smart digital multimeter has a display screen, buttons for selecting measurement types, and probes for testing. It uses an internal processor to quickly store and process data, allowing it to measure voltage, current, and resistance.

What is the voltage range on a multimeter?

A multimeter typically measures voltage in the range of 200 mV to 1000 V and current from 20 μA to 20 A. It generally has an internal resistance of 1 to 20 MΩ, with 10 MΩ being standard. The measurement error is usually less than 1%.

What does voltage mode mean on a multimeter?

In voltage mode, the multimeter probes have high resistance, which ensures accurate voltage measurements. In current mode, the resistance across the probes is low, and measuring voltage in current mode can cause a short-circuit.

What is multimeter sensitivity?

Sensitivity refers to the smallest change in a signal that a multimeter can detect. It defines the multimeter’s ability to respond to slight changes in the input level, such as monitoring a 1 mV DC signal and adjusting it within a ±1 µV range.

How do you check voltage control with a multimeter?

To check a voltage regulator, connect it to a power source and a load, then measure the output voltage across the regulator’s terminals using the multimeter. A battery, wall adapter, or variable power supply can be used as the power source.

What is the working principle of a digital multimeter?

Digital multimeters measure resistance by using a constant current method. A known current (Itest) is sourced to the device under test (DUT), and the resulting voltage (Vm) is measured. The resistance is then calculated using the known current and the measured voltage.

What are common errors on a digital multimeter?

Common errors include signal interference, external noise, and internal current leakage, which can affect measurement accuracy. Identifying these sources of error helps achieve more precise readings.

How do you calculate voltage accuracy on a multimeter?

Voltage accuracy is calculated by adding or subtracting the tolerance from the reading. For example, if the accuracy is ±3%, a reading of 1.20 V with a ± 0.036 V tolerance means the actual voltage could range from 1.16 V to 1.23 V.

Can a multimeter measure AC current?

Yes, to measure AC current with a digital multimeter, set the multimeter to the current function (denoted by ‘A’), select AC or DC as needed, and ensure the circuit is powered off before making the necessary connections.

CEN-TECH 98025 Seven Function Digital Multimeter Manual Download

CEN-TECH 98025 Seven Function Digital Multimeter Manual