1977 Yamaha U1

[John M. Formsma]

Greetings, List.

Have a perpetual problem with a church 1977 U1, #2467469, that I would like
opinions on.

The problem is that the piano experiences large pitch changes every 2-3
months (I tune it 5-6 times per year because of this). I know that the
heating/cooling system at this church is a contributing factor. They
typically have RH extremes of 28%-75%. In the summer, the RH is often over
70%, which is where I measured it yesterday. The piano does not have a DC
system installed, which we know would help matters some at least.

I had last tuned this piano on 4/6/01 with the temperature and humidity at
72F and 63%. The piano was basically at A440 at that time. Yesterday, the
temp was 70F and the RH was 70%. The piano was sharp everywhere--A4 was +12,
A3 was +20, the bass was about +7, and the treble was about +10.

I don't service that many U1s this often, so I don't get to monitor pitch
changes like I do with this one. Is it typical to expect that much change
with a 7% RH increase? There was a pitch raise/tune to A440 in 2/2001 (at
around 33%RH), which would effect that much change by July if the 4/6/01
humidity level had not had time to affect the pitch. Regardless, of this,
the piano has severe pitch changes, even if I "float" the pitch.

Another thing which might cause this piano's pitch changes....  The two most
middle upper screws which attach the plate to the pinblock are loose. One
just turns, and the other behaves as if it tightens, but after a minute, you
can turn it the same amount again. So, these screws are in the middle where
most of the pitch fluctuation occurs. I am wondering if repairing these
stripped out screw holes and/or installing two carriage bolts through the
plate/pinblock would solve most of the pitch instability problem.

Thoughts? Advice?

Thanks much.

John Formsma
Blue Mountain, MS

mailto:jformsma@dixie-net.com