[CAUT] Puzzler: Yamaha G7 clicks

[reggaepass at aol.com]

Dan,



Thanks muchly.  I will try all you have suggested.




Alan


-----Original Message-----
From: Dan Reed <pianoarts at tx.rr.com>
To: College and University Technicians <caut at ptg.org>
Sent: Sat, 26 Jul 2008 1:12 pm
Subject: Re: [CAUT] Puzzler: Yamaha G7 clicks








Hey Alan,


Here are some of the tests I use to isolate the culprit.... 



Duplicating the noise with the action out of the cavity is the
challange....The noise is like the sound of a horse hoove clopping on
cobblestone. The sound It is very similar to hard Capstan contact
felt...(so,  possiabily  the resonance is coming from the vibrating
Maple whippen?)



Test #1:   Holding the hammer up a little higher than 'at rest'
position,  flick / knock the whippen against the knuckle with one
finger, while holding the key from moving..... Note: if you lift the
hammer too high, the hard spot on the knuckle will be missed....


Test #2: You can also  drop the hammer (knuckle) onto the whippen
...Again, It is necessary to hold the key down, to keep the whippen 
from lifting. The amount of pressure pushing the key down will make a
difference in the sound....if you press the key too far down, the
hammer hits the rest cushion...



The source of the noise could be the resonance of the
shank.......another contributing possibility to consider in this
senerio, is hard capstan contact felt...To test for this, hold the key
to keep it still.... get the hammer out of the way, and drop the
whippen down o
n the Capstan....


Why does hard knuckle leather contribute? Probably the same reasons
hard hammers transfer resonate impact  energy...it happens all at
once........


A magic potion...


The source of hardness is likely the hard knuckle core right under the
leather....How about a little compression (pliers) massage therapy?
Consistency will be the trick. Squeezing may change the dimensions of
the knuckle a little...But just a little may kill the noise...


In addition, I like the effect of the Stainless brush on
knuckles...along with a pile of Teflon powder...(Not to be used on
Discliver's...screws the light reading function)


Come to think of it, brush/ steam the capstan contact felt ...this
will slow down the impact on the knuckle....



Dan


Dallas



On Jul 26, 2008, at 12:15 PM, reggaepass at aol.com wrote:





<excerpt>First, let me say that I have never worked on a Yamaha of
this vintage before.  The craftsmanship is excellent.  It has
Schwander wippens.  First we thought it was hardening of the jack felt
punching.  When needling and then replacing that did not solve the
problem, we redirected our attention to the repetition lever,
brushing, needling, and then replacing the drop screw leather pad
("bumper").  Still no change.  We even tried replacing the piece of
action cloth under the repetition lever height adjusting screw
(Schwander, right?), just in case that had somehow gotten hard enough
over the years to make noise when the lever came back up.  Nope, not

that either.


None of the keys were chucking (on a sixty-five year old instrument
that has probably never had any major servicing!).  I have seen that
condition either cause or contribute to this kind of noise before.
 But if any thing, the balance holes are tight on the key pins.

 

Your last thought wins you bragging rights, Dan.  We decided to brush
some knuckles.  An associateA 0observed that the nap of the leather
did not lift as it has on all of the other pianos on which we have
brushed knuckles.  So we endeavored to replace the knuckle.  The
original had a core about 1.6 mm thick, whereas all of the
replacements we had on hand—Renner, Abel and Tokiwa—have cores that
are around 2 mm thick.  Also, the original slot was too shallow for
any of the replacements.  So we used a 2 mm wide file to both widen
and deepen the slot.  New knuckle installed (used Titebond Trim and
Molding glue, which seems to work well), noise gone. Well, as we so
often say in the piano world, “One down, eighty-seven to go!”  


We seem to identified the fix, though I must admit that I'm not sure
how it is that a hard knuckle could cause this problem.  (Then again,
we humans have appreciated sunrises long before we understood what we
were actually witnessing when we saw one.)  If anyone knows 1) WHY the
hard knuckle leather causes this click on a quick release, or 2) HOW
to treat the existing knuckle leather (magic=2
0potion, special armadillo
comb, etc.), PLEASE do share your insights (hopefully before we file
87 more knuckle slots!).

  

May this save someone else all of the time we spent trouble-shooting.

 

Cheers,

 

Alan Eder

 




 -----Original Message-----

 From: Dan Reed <<pianoarts at tx.rr.com>

 To: College and University Technicians <<caut at ptg.org>

 Sent: Fri, 25 Jul 2008 8:57 pm

 Subject: Re: [CAUT] Puzzler: Yamaha G7 clicks


<fixed><bigger>In addition to hard jack stop felt....Some more of the
usual

suspects....




Hard drop screw felt on the rep lever, snapping back on a quick

release, hitting the drop screw.....



'Chucking key...key bouncing on the balance rail on a quick release...



Hard knuckle...bouncing on the jack top...



Dan



Dallas




On Jul 25, 2008, at 7:36 PM,
<color><param>0000,0000,EEED</param>reggaepass at aol.com</color> wrote:



<<excerpt>Yes, you read that correctly, this is a Yamaha model G (not

C) 7, s/n 3xxxxx.  When the key is released slowly, the click isn't

noticeable.  However, on a quick release, it is annoyingly prominent.

 What is the cause?



Alan Eder




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