LDNIO Extension Power Strip (SC4408) Malfunction
The LDNIO SC4408 (also part of the Defender Series) is a heavy-duty power strip designed to support up to 8 devices simultaneously with 4 universal AC outlets and 4 USB-A ports. Newer version (SC4408C) comes with 2 USB-A ports + 2 USB-C ports (supporting PD20W).
- Total Power: Supports up to 2500W at 250V (10A max), making it suitable for household appliances like computers and microwaves.
- USB Output: Features 4 USB-A ports with a total output of 5V/3.4A (17W).
- Cable: Equipped with a 2-meter heavy-duty power cord using a 33% thickened wire core for improved conduction and lower heat.
- Material: Built with fireproof PC material that can withstand temperatures up to 850°C.
- Overload Protection: A dedicated reset button automatically cuts power during an overload to protect connected electronics.
Symptoms:
- All AC outlets unable to turn on.
- Power strip failing to turn on even after you press the reset button.
Analysis:
- Internal Fuse: Fuse at the 13A plug tested working fine
- Broken Reset Mechanism: The reset button feels "mushy" or doesn't have a distinct "click" when pressed, the internal spring or contact point may have failed.
- Appearance: No burning smells, smoke, or visible scorch marks on the housing.
- Connectivity: Tested all AC outlets connected to incoming wires (L/N/E).
KYB8 Circuit Breaker:
- Compact thermal overload protector and circuit breaker primarily used for manual reset protection in electrical appliances and industrial equipment. It features a recessed reset button that pops out during an overload and must be manually pressed back in to restore the circuit.
- The core of the breaker is a strip made of two different metals bonded together. These metals expand at different rates when heated.
- Under normal conditions, these copper contacts are held together to allow current to flow through the device.
- When current exceeds 10A, the resistance in the bimetallic strip generates excess heat (Joule heating). Because the metals expand differently, the strip begins to bend and breaking the circuit.
- The external button "pops out" to indicate the trip. After the bimetallic strip cools and returns to its original shape, the user can manually push the button back in to re-latch the contacts and restore power.
USB Module:
- Capacitors
- 1500uF/10V: The flat top of the aluminum case becomes convex or domed.
- 22uF/400V: No visible damage.
- 4.7uF/50V: No visible damage.
- Summary: Capacitor (1500uF/10V) malfunction
How a Bad Capacitor Affects the KYB8?
A capacitor (1500uF/10V) malfunction impacts the KYB8 breaker in following 2 main ways:
- Short Circuit (Immediate Trip): If the capacitor fails by shorting internally, it creates a path of very low resistance. This causes a massive, sudden surge of current to flow through the KYB8. Since the KYB8 is a thermal breaker, this high current quickly heats the internal bimetallic strip, causing the reset button to "pop" and cut power to protect the wiring.
- Physical Wear and Tear: The KYB8 is a mechanical device. While it is designed to trip, repeatedly resetting a breaker that is tripping due to a faulty capacitor can wear out its internal spring mechanism and contact points. Over time, this can lead to the breaker becoming "broken" (unable to reset or failing to trip when it should).
Action To Be Taken:
- Stop Resetting the KYB8: Repeatedly pushing the reset button while a capacitor is shorted can weld the internal contacts of the breaker or cause the capacitor to vent (pop/leak) aggressively.
- Replace the Capacitor: You need a replacement with the same capacitance (1500uF) and a voltage rating of 10V or higher (using a 16V or 25V capacitor is a common "upgrade" for better durability, provided it fits the space).
- Check the KYB8: Once the capacitor is replaced, if the KYB8 still trips or feels "mushy" when you press it, the breaker itself may have been heat-damaged by the faulty capacitor and should also be replaced.
Cost Involved:
- KYB8 Circuit Breaker: US$1.50
- Capacitor (1500uF/10V): US$1.20 (MOQ: 5pcs)
Tools Required:
Summary:
- Just placed order for the replacement parts on 05/Mar/2026.
- Pending for new parts delivery and implementation.
- Hopefully it is solved after fixing.
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