Yamaha jack question (I figured...)

[William R. Monroe]

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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