Yamaha jack question (I figured...)

[pianolover 88]

Thanks Bill!

Yes, I think you hit on it! I thought the very same thing while looking at it in my shop and observing the jacks and thought that maybe there was not enough LM which could, indeed cause the hanging jack problem. I believe there is INsufficient lost motion! No, the jacks were not hanging up on slow release. I'm reinstalling the action in the morning and will check that there is enough lost motion. 

Thanks!
Terry Peterson

Date: Tue, 18 Mar 2008 20:56:27 -0500
From: pianotech at a440piano.net
Subject: Re: Yamaha jack question (I figured...)
To: pianotech at ptg.org











So, if you file it under unexplained 
mysteries, what does that do for your client?
 
Sheesh, Terry, give us a minute.  
Probably not too tough to figure out if the action is in front of you, but in 
cyberspace a bit more challenging.
 
You said it was in proper regulation.  
How much lost motion was there?  On a slow release of the key, does the 
jack reset properly?  Without more diagnostics, my first instinct is that 
the jacks are hanging on the butts because there is not "enough" lost motion - 
e.g. clearance for the jack to return.  
 
If as you say, everything is sufficiently 
lubricated, I don't suspect more lubrication will help.  Neither do I 
suspect that the jacks being plastic has anything to do with the 
problem.
 
You said the jacks were not resetting.  
Why?  What were they hung on?  Were they hung on the butts?  
Would the jacks reset if you push the hammer forward?  Push the wippen 
down?  I guess what I'm trying to determine is what you did to get the 
jacks to reset as you were diagnosing this.  Presumably, if the centers 
were not too tight or the springs too weak (how did you check this?) you could 
have made the jacks reset somehow by fiddling around in there, moving hammers, 
keys, etc.  More info would help.
 
William R. Monroe
 

  ----- Original Message ----- 
  From: 
  pianolover 88 
  To: PIANOTECH at PTG.ORG 
  Sent: Tuesday, March 18, 2008 7:31 
  PM
  Subject: RE: Yamaha jack question (I 
  figured...)
  
I kinda figured this one was a bit too tough to figure out. I 
  guess I'll have to file this one under unexplained mysteries. But thanks 
  anyway.

Terry 
  Peterson


  
    
    From: pianolover88 at hotmail.com
To: 
    pianotech at ptg.org
Subject: Yamaha 
    jack question
Date: Tue, 18 Mar 2008 15:42:42 -0700


    
    
    Customer owns a yamaha console, only about 11 years old with minimal use. 
    Got a call that some keys were sticking. Upon inspection I confirmed quickly 
    that the problem was *not* in the keys, but the jacks. Turns out that many 
    of the jacks (plastic) are having trouble resetting back under the hammer 
    butts for some reason. This happens whether the damper is depressed or not, 
    when repeating the same notes at a reasonable speed, but less than 
    trill.  

A check of the action determined that the regulation is 
    correct, the centers are not tight, the hammer butt buckskin is not worn at 
    all, and the jack springs are not the problem. I also noted that the top of 
    the jacks have sufficient slickness/graphite. So what could be the source of 
    this problem? The backchecks are also properly regulated. Should I try 
    spraying McLube on the tops of the jack, then brushing on some powdered 
    teflon? Could it be that the jacks being plastic could be part of the 
    problem? 

Terry Peterson

    
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