Sounds like you have a short in the unit. You will have to take it apart and check the power supply for bad semis. My best guess is that your problem lies in the power supply. Let me know how this works out.
The record deck is known as a PS-LK47P.
If you wish, another deck will work as long as it has a magnetic cartridge and no preamp built in.
A Technics SL-1200 is the sort that is fine and a definate upgrade.