I have recently been having problems with my Gibson Standard SG. Whenever I tune all strings, and play an A major bar chord on the 7th fret (X7999X), the 2nd string, B, sounds sharp. But when I play a high power chord like (XX689X), all strings sound in perfect tune. I've tried messing around with the truss rod, raising and lowering action with bridge, and even changing strings. What else should I do, guitar people?
1. See if you've accidently turned the removable tailpiece around. Try turning it around, and see if it's more in tune. I know it sounds simple. But they often fall off, when people change strings.
2. Have you adjusted the saddles? You may just need to set the intonation.
Definitly check the saddles on the bridge. I had to adjust mine when I got my SG. If you don't know how to fine tune it, tune the string in question, make sure the harmonic on the 12th fret is in tune, then make sure the fretted note on the 12th fret is in tune. It takes a litte while to get it perfect, but it makes a difference.
Then again, I might be wrong about that procedure.