Reducing the check distance and/or needling the backcheck felt may help too. On Wed, Jan 21, 2009 at 11:49 AM, Paul McCloud <pmc033 at earthlink.net> wrote: > Hi, Gregor: > Check the damper spring tension also. Too much tension will produce > the same symptoms. I found this while trying to diagnose a similar problem > with a Chinese upright piano we were selling. > On another American brand, their new Schwander (loop type) action had > bobbling problems. I had to increase the letoff distance a bit to reduce > the problem. I figured that the return springs were too "weak" and soft > play would not be hampered if I did that. It seems that some pianos are > prone to this even when new. > Paul McCloud > San Diego > > > > ----- Original Message ----- > *From:* Gregor _ <karlkaputt at hotmail.com> > *To: *pianotech at ptg.org > *Sent:* 01/21/2009 8:23:17 AM > *Subject:* [pianotech] Bobbling hammers and jack spring pressure? > > List, > > is there a way to ease the jack spring? I have problems with a Yamaha P121N > upright that has bobbling hammers. The hammer butt is dancing on the jack > tip. All regulation measures are okay and there is enough aftertouch. I > suspect the jack spring being too strong. Any thoughts how to get it right? > > There is no lost motion, check is about 15 mm, aftertouch is okay and I > gave some talkum powder to the jack tip and the let off button. The only > thing that helped was to set the let off to 10 mm, but that´s not a > satisfying solution. The strange thing is that one could play without > bobbling hammers but something makes the player stop pressing down the key > before the let off point. A very subtile resistance gives the player a hint > that the key is pressed down now, but that´s not right. The player could and > should press further on. The strange thing is that this problem is new for a > few days. I should mention that we had very dry air last weeks and the > customer has a floor heating. Therefore I suspect a connection between this > problem and the dry air. > > Any comments? > > Gregor > > ------------------------------ > What can you do with the new Windows Live? Find out<http://www.microsoft.com/windows/windowslive/default.aspx> > > -- Regards, Jeff Deutschle Please address replies to the List. Do not E-mail me privately. Thank You. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech_ptg.org/attachments/20090121/03c0afcd/attachment.html>
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