Mostly, the batteries are used to backup the data for when the AC power is turned off overnight. Check the input rating on its AC adapter (if it's like mine, it'll be 100 volts at 50-60 Hz.) Australian wall socket power is 230-240 volts at 50 Hz. I don't imagine you were able to plug the AC adapter directly into your wall, but if you did, you may have damaged the circuit in the AC adapter. Ideally you need to use a step-down transformer (expensive), or an alternative AC adapter (not really expensive). If your DekaTama is like mine, it requires 6 volts, 200 mA. Some electronics stores sell generic / multi-purpose replacement AC adapters. Find one that has the same size plug that fits into the back of the DekaTama, and has the same polarity (again, if it's like mine, it's positive in the center with ground on the outside.) The output voltage must match (6 volts), but the current rating can be the same or higher (200 mA or more.)
