Piano Disc pedal mechanism problem

[John M. Formsma]

Dean,

Thanks very much for this. I will check everything you mentioned.

JF

Dean May wrote:
> HI John
>
> First, make sure the pedal solenoid is properly adjusted. On a grand the
> first adjustment to make is the amount of damper lift. This is done by
> adjusting the large nut on the end of the rod sticking out of the solenoid.
> Pull down on the rod to manually lift the dampers. The bicord wedges should
> just be below the top of the strings- you don't want them coming above the
> strings. It is important (critical) to minimize the amount of damper travel.
> Make sure that the lever does not hit the stop screwed into the keybed above
> the pedal lift rod. You definitely do not want the solenoid jamming the
> lever against that stop. That will create its own noise. 
>
> Once the damper lift is set, tighten the jam nut. Then you must adjust the
> lost motion. This is done by turning down the stop at the top of the
> soleniod. There is a jam nut on the top. Loosen it then you can turn the
> threaded rod to raise or lower the stop. Lower the stop until the dampers
> just start to ring, then back off a little. You want very little to none
> lost motion. Then tighten the jam nut on top.
>
> Doing these adjustments will set the trapwork to the absolute minimum travel
> and may eliminate any noise. If the noise persists you must determine if
> there is anything hitting at any point along the trapwork. Often the passage
> for the lift rod through the keybed is narrow and sometimes there is
> interference there. 
>
> Another thing to check. I've seen this on Young Changs. There is an
> extension off the backside of the keybed that the trapwork pivot brackets
> are screwed to. I have diagnosed wood on wood knocking noises coming from
> that extension. As the solenoid engages it loads up the trapwork creating a
> bending load on that extension. After seeing that happen I made a design
> change to all future Young Chang installations. I simply use a 90 degree
> mending plate bracket (available in all hardware sections) to rigidly anchor
> the backside of that extension to one of the beams, preferably as close to
> the trapwork pivot as possible. Then make sure that the large screws holding
> the extension to the keybed are really, really tight. You might even need to
> take the extension off and use some urethane glue to secure it in place. 
>
> Hope this helps. 
>
>
> Dean
> Dean May             cell 812.239.3359
> PianoRebuilders.com   812.235.5272
> Terre Haute IN  47802
>
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
> Of John M. Formsma
> Sent: Tuesday, November 14, 2006 9:27 PM
> To: Pianotech List
> Subject: Piano Disc pedal mechanism problem
>
> Piano Disc in a 1995 Young Chang G-150. (I'm assuming the PD system is about
> as old as the piano.)
>
> When the system is playing the piano, the sustain pedal makes a knocking
> sound. It's more like wood-on-wood or wood-on-metal than a clicking
> metal-on-metal type sound. The pedal doesn't have this noise during normal
> human play.
>
> I know little about PD systems except for the obvious things like
> reinstalling actions, basic electronics, etc. After 15 minutes of peering,
> replacing a worn felt, and head-scratching, I told the owner I'd ask others
> rather than learning with her $$.
>
> As far as I can tell, the problem is not in the "actuator" that engages the
> pedal. (I did replace the felt under the actuator rod, so that can be ruled
> out as a source of noise.) The noise seems to come more from the rod that
> goes up from the PD pedal bracket into the action cavity. 
> There is a rubber washer under the nut on the threaded rod that could be
> worn, but since I don't have those, I didn't attempt a replacement. 
> Moving the PD pedal bracket slightly did lessen the noise, so I'm wondering
> if something is out of alignment. But nothing looked obvious.
>
> Anyone know what this noise might be from, and how to tell a non-PD tech how
> to fix it?
>
> Thanks,
> John Formsma
>
>
>
>