A lot of switching power supplies have a switch (Or jumper dongle) that changes the input rectifier from a fullwave (240VAC) to a voltage doubler (120VAC)..... I assume yours has no such switch, however, you can check if it has a voltage doubling rectifier on the input. If it does, it will have 2 large input caps connected in series which are easy to spot. If so, you can modify it for fullwave input. This would raise the minimum input voltage and the max by about 2X. You would have to open the supply though.