Pianotech

I recently was called to investigate what was described as sticking keys on an institutional Yamaha P22 (think heavy student use and abuse).  What seems to be the problem is the plastic jack that is used in this piano would get hung up on the buckskin where there is a change in angle on the hammer butt right before it gets to the reset position.  A query to Yamaha tech support resulted in a fix (which I have yet to try) that involves shimming the balance rail up slightly and then readjusting the capstans.  Personally this seems a bit strange to me as the two adjustments should end up with the wippen at exactly where it was originally and how it would act to change the way the jack interacted with the hammer butt is confusing to me.  Anyone with insights and experience with this I'd really appreciate their comments.  By the way, the hanging up problem usually happened when playing softly (and with a soft touch) and would even happen when the soft pedal was depressed.  This means it is not a regulation problem since pushing down the soft pedal creates about an 1/8" gap between the jack and the hammer butt in resting position ... ie: it has plenty of clearance in order to reset.

Looking forward to the comments.

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Neil Vanderschaaf
Round Rock TX
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When said the problem is worse when the right pedal is being used indicates to me the reason the Jack is not getting back under because the back end of the keys are not going down far enough. (With the dampers engaged, the damper levers are actually helping return the key).

My advice is to remove the keys and ease the balance rail hole. To make sure you’ve done it right, lift up the key so that the balance rail pin is below the bushing. Let the key drop and it should go down to rest position with ease. Try to play the note softly and see if the jack returns.

Wim
Sent from my iPhone

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Neil Vanderschaaf
Round Rock TX
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Original Message:
Sent: 04-24-2024 18:43
From: Wim Blees
Subject: Yamaha P22 jacks hanging up on the hammer butt

When said the problem is worse when the right pedal is being used indicates to me the reason the Jack is not getting back under because the back end of the keys are not going down far enough. (With the dampers engaged, the damper levers are actually helping return the key).

My advice is to remove the keys and ease the balance rail hole. To make sure you've done it right, lift up the key so that the balance rail pin is below the bushing. Let the key drop and it should go down to rest position with ease. Try to play the note softly and see if the jack returns.

Wim
Sent from my iPhone

Original Message:
Sent: 4/24/2024 6:44:00 PM
From: Wim Blees
Subject: RE: Yamaha P22 jacks hanging up on the hammer butt

When said the problem is worse when the right pedal is being used indicates to me the reason the Jack is not getting back under because the back end of the keys are not going down far enough. (With the dampers engaged, the damper levers are actually helping return the key).

My advice is to remove the keys and ease the balance rail hole. To make sure you’ve done it right, lift up the key so that the balance rail pin is below the bushing. Let the key drop and it should go down to rest position with ease. Try to play the note softly and see if the jack returns.

Wim
Sent from my iPhone

Neil,

Your problem (a bit of a long shot) is that the capstan has developed a concave pocket in the wippen felt. If the angle of attack of the key is incorrect, the capstan slides into an increasing concaved pocket. If the capstan and wippen are not interacting within the ideal involute curve, such as how two gear teeth interact, this could cause the two parts to jam…. somewhat. By raising the balance rail, the capstan now "rolls" against the wippen. This is the reason that key height is important.  Yamaha may be aware that either there was a misalignment of the key and wippen at the factory or they are aware, over time, that the P22 model is venerable to this phenomenon.

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Roger Gable RPT
Gable Piano
Everett WA
(425) 252-5000
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I'm going to support Yamaha's recommendation. Shimming the rest rail a bit is necessary to compensate for unwanted increased blow distance due to the rest rail felt compacting as the piano ages. This is normal. Adjusting the capstans is also necessary to adjust for proper lost motion. You need a bit, and both of these adjustments will affect lost motion. Both of these procedures are normal for new piano prep, but if it hasn't  been done it could be a cause for what you are experiencing. As the piano ages, and is played, they need to be checked and readjusted on occasion. After you have checked both of these adjustments then Wim's recommendation of easing the keys is an important next step. Be careful with this step as overeasing the keys can cause other problems. Go easy and, as Wim says, only as far as necessary to let the keys drop with ease when lifted in front. And as long as you're in there doing these adjustments, check and adjust letoff. These are all very quick and easy tasks and when completed can noticeably improve performance. 

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Geoff Sykes, RPT
Los Angeles CA
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The fix recommended by Yamaha involves shimming the balance rail (not the hammer rest rail). This will slightly change/increase the angle of the keys, which will address the interaction with the wippen already mentioned, and correct for the keys not being at the proper height above the keyframe. Yamaha uprights appear to be VERY sensitive to very minor discrepancies in these measurements. Of course the other regulation settings also need to be checked.