Step down adapters can change the voltage. BUT In addition to voltage, the frequency at which the power is generated may also differ, usually from 50 Hz to 60 Hz. While it is possible to convert voltage, it is not possible to convert frequency, though some devices are built to handle these differences.
Check the label on your electrical device.
eg: IMPUT: AC 100V-240V ~ 1.0A 50/60 Hz This device was designed to be used over a wide range of voltage and at different frequencies. In this particular example, the device can use anywhere from 100 volts to 240 volts and can operate on either a 50 Hz or 60 Hz system; If the devise's label has for instance AC 120V ~ 3.0A 60Hz then it can only be used with 120V 60Hz electrical systems.
Hope this was helpful.