
you didn't say it was an RG prestige.
I think you have to double-check the solders (like CD kinda said). It could be something even at the input/output jack of the guitar but I would guess it is indeed not-so-good solders.
What you can try if you can't identify the issue, is to unsolder everything and do it by process of elimination. You don't have to string it up to avoid the buzz, so you can simply solder, test, add component, until you're done.