FNIRSI FNAC-28 USB Charging Troubleshooting FAQ Malaysia

Introduction

USB charging problems are common among smartphone users, electronics technicians, computer repair shops and portable electronics users in Malaysia.

A smartphone may charge slowly, a power bank may disconnect unexpectedly, or a high-wattage USB charger may fail to activate fast charging.

These problems can involve USB voltage, charging current, cable resistance, charging protocol compatibility, device temperature or power supply limitations.

The FNIRSI FNAC-28 USB Tester is a compact USB measurement instrument that can help users observe electrical conditions in compatible charging systems.

It provides useful measurements for investigating USB charger performance, charging cables and power bank output behaviour.

This FAQ guide answers common questions about USB charging troubleshooting, explains what different measurements mean and identifies when additional testing equipment may be required.

1. What Is FNIRSI FNAC-28?

The FNIRSI FNAC-28 is a USB digital tester designed for monitoring electrical parameters in compatible USB charging arrangements.

Its main applications include:

• USB Voltage Measurement

• USB Current Measurement

• USB Power Monitoring

• USB Charger Troubleshooting

• Power Bank Output Testing

• Supported USB Cable Resistance Testing

• Selected Fast-Charging Protocol Testing

The instrument is useful for preliminary electrical measurements.

However, it does not replace a laboratory-grade power analyser, dedicated USB PD analyser or electrical safety tester.

2. FNIRSI FNAC-28 Technical Specifications

Important: The instrument's maximum rated power does not mean that it can negotiate every USB-C charging mode or verify all USB PD power levels.

Always follow the manufacturer's operating instructions and equipment ratings.

3. Why Is My Smartphone Charging Slowly?

Slow smartphone charging can have several causes.

Common possibilities include:

• Low Charger Output Power

• USB Cable Resistance

• Charging Protocol Incompatibility

• Battery Nearly Fully Charged

• High Battery Temperature

• Poor USB Connector Contact

• Device Charging Restrictions

Recommended Troubleshooting

First, check the charger's rated output.

Next, inspect the charging cable and connector.

Then, use a compatible USB tester to observe the operating voltage, current and power.

Compare the results with a known-good charger and cable under similar conditions.

A low charging power reading does not automatically mean that the charger is defective.

The smartphone may be intentionally limiting charging current.

4. Why Does My 65W USB Charger Only Deliver 10W?

A 65W rating usually describes the charger's maximum supported output under specified conditions.

It does not mean that every connected device will continuously draw 65W.

For example:

Measured voltage: 5V

Measured current: 2A

Calculated power:

5V x 2A = 10W

Possible explanations include:

• The device does not support the charger's higher-power mode.

• The required charging protocol was not negotiated.

• The cable does not meet the charging requirements.

• The device battery is nearly full.

• Thermal charging controls are limiting power.

Actual charging power depends on the charger, cable, connected device and operating conditions.

5. How Can I Check USB Charger Output Voltage?

A compatible USB tester can display the operating voltage of a USB charging connection.

Basic Procedure

1. Confirm the charger output rating.

2. Inspect the charger and cable.

3. Connect the FNIRSI FNAC-28 using a supported arrangement.

4. Connect a suitable USB load.

5. Observe the voltage reading.

6. Compare the result with the applicable charger specifications.

For example, a conventional 5V charger may display a voltage close to its nominal rating.

The acceptable voltage range depends on the applicable specifications and measurement conditions.

6. How Can I Measure USB Charging Current?

USB charging current is measured in amperes (A).

The FNIRSI FNAC-28 can display current flowing through a compatible USB test connection.

For example:

Voltage: 5.05V

Current: 1.50A

Calculated power:

5.05V x 1.50A = 7.58W

Current may change automatically during smartphone charging.

Therefore, a single current reading should not be interpreted as the charger's maximum output capability.

7. What Is the Difference Between USB Voltage, Current and Power?

These three electrical quantities describe different properties.

The relationship is:

Power (W) = Voltage (V) x Current (A)

For example:

9V x 2A = 18W

Understanding this formula helps users interpret USB charging measurements.

8. Why Does USB Charging Disconnect Intermittently?

Intermittent charging may be caused by:

• Loose USB Connectors

• Damaged Charging Cables

• Poor Electrical Contact

• Charger Protection Behaviour

• Device Charging Port Problems

• Power Supply Instability

Recommended Checks

Inspect the connectors for visible damage.

Test with a known-good compatible cable.

Compare the behaviour using another suitable charger.

Observe voltage and current where safe and practical.

Stop using equipment that shows abnormal heating, damaged connectors or burning smells.

9. Why Does USB Voltage Drop When Charging Current Increases?

Electrical resistance in cables and connectors causes voltage drop when current flows.

The relationship is:

Voltage Drop (V) = Current (A) x Resistance (Ohm)

For example:

Current: 2A

Resistance: 0.15 ohm

Calculated voltage drop:

2A x 0.15 ohm = 0.30V

Higher current produces greater voltage drop across the same resistance.

However, a measured reduction in USB voltage may also involve charger regulation or a change in charging mode.

A single voltage measurement cannot independently identify the source of the voltage drop.

10. How Do I Know Whether My USB Cable Is Good?

USB cable quality depends on several factors.

These include:

• Conductor Resistance

• Current Rating

• Connector Quality

• Cable Construction

• Charging Protocol Compatibility

• Mechanical Durability

A practical comparison can be performed using two compatible cables under equivalent test conditions.

Measure voltage and current using suitable equipment.

If one cable produces significantly greater voltage loss under the same load, it may warrant further investigation.

Low cable resistance does not guarantee that a cable supports every USB fast-charging or data communication feature.

11. Can FNIRSI FNAC-28 Test USB Cable Resistance?

The FNIRSI FNAC-28 provides a supported cable resistance testing function.

Users should follow the manufacturer's instructions for the required connection arrangement and measurement procedure.

Cable resistance results should be interpreted alongside cable specifications and operating conditions.

A resistance measurement alone cannot verify every aspect of USB cable quality.

For example, it does not independently certify USB data performance, USB PD compliance or E-Marker characteristics.

12. Why Does Fast Charging Work with One Cable but Not Another?

Some fast-charging systems require cables with particular electrical characteristics or identification features.

Possible differences include:

• Current-carrying capability

• Cable resistance

• Connector condition

• Proprietary charging compatibility

• USB-C E-Marker requirements

A replacement cable may support conventional charging but not the intended fast-charging mode.

Use cables that meet the charger and device manufacturer's requirements.

13. Can FNIRSI FNAC-28 Detect Fast-Charging Protocols?

The FNIRSI FNAC-28 supports selected fast-charging protocol detection and triggering functions.

Supported protocol families include selected implementations of:

• Qualcomm QC2.0

• Qualcomm QC3.0

• Samsung AFC

• Huawei FCP

• Huawei SCP

• Selected Proprietary Charging Protocols

Actual compatibility depends on the instrument version, charger and protocol implementation.

Do not assume that every version of a proprietary fast-charging system is supported.

14. Can FNIRSI FNAC-28 Test USB Power Delivery?

The FNIRSI FNAC-28 has USB-C connectivity and can measure compatible USB electrical conditions.

However, it does not support USB PD active triggering or USB PD packet capture.

For detailed USB Power Delivery negotiation analysis, a dedicated USB PD analyser is required.

For testing specific USB PD output profiles, suitable PD negotiation equipment and electronic loads may also be necessary.

USB-C connectivity does not automatically mean full USB PD protocol analysis capability.

15. What Is the Difference Between QC and USB PD?

Qualcomm Quick Charge (QC) and USB Power Delivery (USB PD) are charging technologies with different communication methods and implementation requirements.

Both can support higher-power charging in compatible systems.

However, compatibility depends on the charger and connected device.

A charger supporting QC does not automatically support every USB PD charging mode.

16. Why Does My Power Bank Charge Slowly?

A power bank's output performance depends on its design and operating conditions.

Possible causes include:

• Limited output power

• Incompatible charging protocol

• Poor cable quality

• Low internal battery level

• Thermal protection

• Connected device charging restrictions

Check the power bank's output specifications and compare measurements under suitable conditions.

Power bank capacity in mAh is not the same as maximum charging power in W.

17. Why Does a 10000mAh Power Bank Deliver Less Than 10000mAh at 5V?

The advertised battery capacity often refers to internal battery cells operating at a nominal voltage around 3.7V.

USB output may operate at 5V.

For example:

10000mAh = 10Ah

Nominal stored energy:

10Ah x 3.7V = 37Wh

Assume an illustrative overall energy delivery ratio of 85%.

Estimated USB output energy:

37Wh x 0.85 = 31.45Wh

Equivalent output charge at 5V:

31.45Wh / 5V = 6.29Ah

Therefore:

Estimated USB Output Charge = 6290mAh at 5V

This is a theoretical example, not a guaranteed result.

Compare power bank energy in Wh rather than directly comparing mAh values measured at different voltages.

18. Can FNIRSI FNAC-28 Measure Power Bank Capacity?

The FNIRSI FNAC-28 can assist with compatible USB output measurements.

However, a complete power bank capacity evaluation requires controlled discharge testing and suitable accumulated energy measurement.

A practical setup may include:

• Fully charged power bank

• Suitable electronic load

• Compatible USB tester

• Appropriate energy measurement method

• Defined discharge endpoint

The FNIRSI FNAC-28 cannot directly measure the internal battery cell capacity through a USB output connection.

19. Can FNIRSI FNAC-28 Test USB Charger Load Performance?

Yes, the instrument can measure compatible USB electrical parameters while a separate suitable electronic load draws current.

A simplified arrangement is:

USB Charger -> FNIRSI FNAC-28 -> Electronic Load

Technicians can observe voltage, current and power at different load levels.

However, the FNIRSI FNAC-28 is not itself a programmable electronic load.

All equipment must remain within its rated operating limits.

20. Why Does My USB Charger Become Hot?

USB chargers generate some heat during normal operation because electrical energy conversion is not perfectly efficient.

However, excessive heating may indicate a problem.

Possible causes include:

• High electrical load

• Poor ventilation

• Elevated ambient temperature

• Internal component problems

• Damaged connectors

• Unsuitable operating conditions

A USB tester may help observe electrical output conditions.

However, it cannot independently verify internal charger temperature or electrical safety.

Stop using a charger if it produces abnormal heat, burning smells, smoke or visible damage.

21. Can FNIRSI FNAC-28 Detect a Fake USB Charger?

A USB tester may reveal inconsistencies between advertised specifications and measured electrical behaviour.

However, these inconsistencies do not automatically prove that a charger is counterfeit.

Authentication may require checking:

• Manufacturer information

• Product markings

• Serial numbers

• Packaging

• Official documentation

• Authorised supplier records

The FNIRSI FNAC-28 cannot independently authenticate a USB charger.

22. Is FNIRSI FNAC-28 Suitable for Electronics Repair Shops?

Yes. The instrument can support preliminary troubleshooting involving compatible USB electrical measurements.

Typical applications include:

• Smartphone charging investigations

• USB charger comparisons

• Power bank output monitoring

• Cable resistance comparisons

• Selected fast-charging protocol checks

For more advanced testing, technicians may also require a digital multimeter, oscilloscope, electronic load or dedicated USB PD analyser.

23. Can FNIRSI FNAC-28 Replace a Digital Multimeter?

No.

A digital multimeter is designed for general electrical measurements across a wider range of circuit applications.

The FNIRSI FNAC-28 is intended for compatible USB electrical measurements.

Both instruments can be useful in an electronics workshop.

Choose the instrument according to the electrical parameter and circuit being tested.

24. USB Charging Troubleshooting Quick Reference

This table provides preliminary troubleshooting guidance rather than a definitive diagnosis.

25. USB Charging Troubleshooting Checklist

Before replacing a charger or power bank, technicians should check the following:

1. Confirm the Rated Output Voltage and Current.

2. Inspect the USB Cable and Connectors.

3. Check the Connected Device's Charging Requirements.

4. Measure USB Voltage, Current and Power.

5. Compare with a Known-Good Charger.

6. Compare with a Known-Good Cable.

7. Check Fast-Charging Protocol Compatibility.

8. Consider Battery Temperature and Charge Level.

9. Use a Controlled Electronic Load Where Appropriate.

10. Record Measurements Before Recommending Replacement.

A systematic approach helps reduce unnecessary replacement of working equipment.

26. Where to Buy FNIRSI FNAC-28 USB Tester in Malaysia?

MTM Precision Sdn Bhd supplies electronic testing and measuring instruments for professional, educational and technical applications.

Customers searching for FNIRSI FNAC-28 Malaysia, USB Charging Tester Malaysia or USB Power Meter Malaysia can contact MTM Precision for product pricing, availability and suitable instrument recommendations.

The FNIRSI FNAC-28 is useful for customers interested in USB charger troubleshooting, power bank output testing, charging cable comparisons and selected fast-charging protocol investigations.

MTM Precision serves customers throughout Kuala Lumpur, Selangor, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Kelantan, Terengganu, Perlis, Sabah and Sarawak.

Please contact our team to confirm current stock and delivery arrangements.

Contact MTM Precision Sdn Bhd

For FNIRSI FNAC-28 USB Tester Malaysia, USB charging troubleshooting and electronics measurement instrument enquiries:

MTM Precision Sdn Bhd

Showroom & Service Centre

No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.

Tel: 03-8080 7172

WhatsApp: +6016-660 7346

Email: mtmpre@yahoo.com

Website: www.mtmpre.com.my

Contact MTM Precision today for FNIRSI FNAC-28 pricing, availability and suitable USB charging diagnostic equipment recommendations in Malaysia.

Conclusion

USB charging problems can involve several interacting factors, including charger output power, USB cable resistance, charging protocol compatibility, connector condition and device charging controls.

A systematic troubleshooting procedure helps identify possible causes before replacing equipment.

The FNIRSI FNAC-28 USB Tester provides useful voltage, current and power measurements for compatible USB charging arrangements.

It can support preliminary troubleshooting of USB chargers, power banks and charging cables.

However, specialised equipment may be required for detailed USB PD analysis, controlled battery capacity testing and electrical safety verification.

For customers searching for USB Charging Troubleshooting Malaysia, USB Charger Tester Malaysia or FNIRSI FNAC-28 Malaysia, MTM Precision Sdn Bhd can assist with product enquiries and suitable electronics testing equipment recommendations.