Electronics Repair Questions? Ask an Electronics Technician
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, is the Pioneer completely/electrically dead?
Yes; the voltage was almost doubled likely causing a fault in the power supply.
this would then be an internal hardware issue particularly. Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?
A step-down transformer yes BUT only after it has been repaired.
Please post back how you would want to approach this and/or should additional information be needed.