The cut black & yellow wires are the mains input. Ideally, it should be removed and the capacitors (or replacements) remounted with silastic, but you don't have to do that until you're ready. It is sometimes a big problem as it breaks down and becomes corrosive. The orange stuff is glue to keep them from breaking off or vibrating. You are correct that a proper power connection would provide for the green/yellow protective earth to be connected to the metal chassis of the instrument. And then you would get a standard IEC power connector and install it into the hole to provide a proper mains power connection. Ideally, you would disassemble the instrument and confirm that the black and yellow wires still connect to the designed mains power 240V AC input. Even if the black and yellow wires ARE the 240V AC mains input connection, having exposed wires like that going through an unprotected hole in the metal panel is dangerous on several levels. I would NOT recommend doing that without further research. However, if there is any internal modification, that experiment has a good chance of blowing up in your face (perhaps literally). You COULD simply attach your mains power cord to the black and yellow wires and try it. Since the unit appears to have been modified, you don't really know for sure that those black and yellow wires are the mains (240V) input connection. There is no 'positive' or 'negative' with AC (Alternating Current). The name-plate power rating for the instrument is 240V AC (mains power). Probably going to have to strip the black wire a bit more considering that those two strands of wire are not going to help much. Appreciate any help, thanks alot and photos down below. (Another reason I am skeptical and slightly apprehensive of this is that I had assumed there would be 3 wires, one to be earthed?) After this is sorted out I was planning on just soldering each corresponding wire together and separating these with insulating tape. This is where the problem lies as I'm confused as to which connection I should make with the KORG.

At the end of this there is two wires blue and maroon. With it I also have a NICEIG 3 prong power adapter. Sticking out the back of the korg is two power wires (yellow and black), I am assuming yellow = positive, black = ground. I usually confine myself to guitar pedal electronics so I do not have much experience with this side of things so I need a bit of help. The manual for the piano is - Hi guys, I live in England and have just bought this digital piano - from the 80's I believe - and the power adapter at the back is missing with two wires sticking out.

Korg concert 5000 review