MX100 Follow-up

[Roger Jolly]

Good Job Tom,
Now the 64K question, Who started the screw up, A dealer? The furniture
person? or Finally an Ill imformed piano tech?
Roger



At 12:03 AM 19/12/99 -0800, you wrote:
>To update the list about the Yamaha MX100 problem (studio upright with
>Disklavier):
>
>I returned to the customer today armed with a long list of things to
>look for. Having all your suggestions was very helpful although no one
>had the problem nailed. It might have helped the diagnosis if I had
>taken DW/UW measurements on the _black_ keys, hindsight being better
>than foresight.
>
>The first thing I checked was the case for evidence of a fall and, right
>away, I found just that. Someone had left some obvious scratch marks
>from sandpaper plus there was orange peel black lacquer over that on the
>front surfaces of the cheeks and toes (the case is polished ebony).
>After all my careful checking of down-weights and up-weights last time,
>I missed this amateurish repair job staring right at me.
>
>Next, I looked very carefully to see if the fall had changed the
>relationships between the keys, action and strings. The right cheek was
>damaged more extensively - a wider area was repaired - and I had thought
>that this might have something to do with the treble keys being harder
>to depress. 
>
>But everything looked normal. The dowel capstans were in the middle of
>the wip heels from bass to treble. There was no evidence that the keybed
>or action support bolts had moved. I removed the action and saw that the
>rail was not bent and the little rubber-booted screw, mounted on the
>back of the main action rail, was contacting the plate strut (so no
>flexing).
>
>After I laid the action aside, I exercised the keys up and down and
>found them to be quite free... until I got past the middle of the piano
>and noticed that there was some kind of resistance to key motion in the
>treble, almost like very tight balance pin holes. But then I noticed the
>metal key stop rail which, in the Disklavier, runs directly over the
>balance rail between the two rows of pins. As I lifted the bass keys to
>check for balance pin hole tightness, I could lift the keys slightly
>before they contacted the felt underneath the key stop rail. But in the
>treble, there was no clearance at all. Someone had unthinkingly
>tightened two of the fixing screws, which bear against coil springs
>underneath the rail, too far which caused the keys to bind slightly. (It
>was not the usual nut on the bottom, nut on the top design.)
>
>As soon as I backed off the screws a couple of turns, there was
>clearance above _all_ of the key buttons, the touch returned to normal
>and the customer was happy. 
>
>1 hour of sleuthing and 1 minute of adjustment did the trick. 
>
>Tom
> 
>-- 
>Thomas A. Cole, RPT
>Santa Cruz, CA
>mailto:tcole@cruzio.com
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505