When the LED lamp is difficult to light, sometimes touch the LED lamp tube can light or light rolling, this may be C3, C4 capacity is insufficient, not paired. If a single small power energy-saving lamp lit after the filament red or luminous phenomenon, should also check WHETHER D1 — D4 soft breakdown, C1 is installed or leakage, power supply part without short circuit. The cores of choke L and oscillating transformer B are broken. If you change cores only, there are three things to note. Use the magnetic core that meets the requirements, otherwise it may make the inductance value of choke have a big difference, bury hidden trouble to energy-saving lamp; Magnetic gap can not be too small, so as to avoid magnetic saturation.