Adjusting truss bar on a RBX 250?

[Alloy007p]

I got a Yamaha RBX 250 awhile ago used, and I need to adjust the truss bar because the strings are vibrating against the fret board. The problem is is that there's no "hole/grove" for any sort of alen key or screw driver to fit into-its just flat. So do I need to remove the whole neck, need a special tool, or is the truss just screwed?

[rumblethump]

You need to remove the neck.

[XylemBassGuitar]

Yep,

Also, are you fairly familiar with truss rod adjustments and how they work in general Alloy007p?

If you are, my apologies for the assumption...

But, if you aren't, you might consider looking into it a little further and maybe seeing if raising the action would be a better solution to you problem...

[Alloy007p]

I'm not too familiar, but I've been reading over lots of stuff and I think I have a pretty good understanding of adjusting the truss rod. So just makeing sure but to remove the neck I would unscrew this back plate right?

[exkaos]

Truss rod adjustment is kind of a pain on these basses because removing the neck is about the only way I've found to get at the nut on my RBX350. If the neck is bowed significantly, you may have to repeat the process a few times.

I slacken the strings (it's not necessary to remove them entirely) and then remove the four backplate screws. Once the neck is off, I use an 8 mm socket to tighten (or loosen) the nut, never more than a half turn at a time. Then, screw the neck back on, tune up the strings and see where you're at. If it's still not where I want it, I let it settle for a while and then remove the neck and give the nut another crank. You may find that you have to raise the bridge saddles once you've straightened the neck to get rid of fret buzz.

In your case, it sounds like you may want to loosen the nut a tad to add some relief (bow) to the neck. If you look down the edge of the fretboard and the neck is already straight, or has a very slight up-bow, you probably don't want to mess with the truss rod, but can fix the buzz just by raising the saddles.