I dont see an LED back lights listed for that unit. This means it uses CFL lights. The link I am posting for this is a major parts supplier, as you can see the power supply for the back light is out of stock, you can use the info there to get the OEM part number and then search for it on ebay etc. Good luck because the unit is obsolete and you may end up having to get the board repaired. https://www.shopjimmy.com/catalogsearch/result/?q=1913+tdxb+
If you will go to your remote and look on the back, or just the name of it, you can look it up online and it will give you all the codes to the TV's it will hook up to. It's going to depend on which Polaroid TV you have too.