Ukulele high G string goes out of tune when pressed

[ukuo57]

Hi all,

I have this issue. Let's say my ukulele is totally in tune. When I go to play, say an F chord, the chord sounds out of tune. Reason being is that the high G string, whenever I press on any fret, makes the resulting note sharper than it should be. So everything I play with the high G string is out of tune. I tried tightening the screw and that didn't help. Do I need to replace my strings? I don't remember having this problem earlier.

Thanks

 

[SunnyIsleMark]

First thing I'd suspect is the G string nut slot being cut too high, or cut too narrow for the string to fully sit at the bottom of the slot.

 

[stevepetergal]

From your description, it sounds like you should not be tightening the screw on your tuner. If the string is staying up to pitch (played open) it's not the tuner. If the string actually changes pitch and needs to be re-tuned as soon as you start playing, it may be something to do with the tuner or the nut slot being too tight and not allowing the string to slide smoothly (your description doesn't indicate this).
First you must determine whether or not the problem is only with the one string. If the other strings go sharp when fretted and this is less of a problem as you move up the fretboard (at higher numbered frets) your action is probably high at the nut. If it's just the one string, is that string noticeably higher above the fretboard than the others (unlikely but possible)? If it is, there's your problem.
If the string is not holding pitch, (again not what your description suggests) first be patient. sometimes one string will take longer that the others to stop stretching. But, if the strings are well "settled-in", then it may be the tuner. If you need to adjust the tuner by tightening the screw on the button, make very slight turns. Over-tighten, and you'll crack the button.
If you take this instrument to your local repair shop, it'll almost certainly cost you nothing to diagnose.