When the flash switch is turned on, Yin Yan can hear a faint sound, but what is the reason why the standby indicator is not on?

A flash such as "Yin Yan" will sound when it starts to charge the storage capacitor. When the battery is fully charged, the sound fades and the ready indicator lights up. This process is normal for about tens of seconds. If the battery power is insufficient or the storage capacitor leaks a lot, the charging time will be prolonged. If the required voltage cannot be charged before the indicator light is on, it should be repaired.