[CAUT] Puzzler: Yamaha G7 clicks

[Dan Reed]

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 on 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:




> 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 potion, 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
>
> 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, reggaepass at aol.com 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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>  
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