Yamaha GH1

[Roger Jolly]

Hi Stan,
            No bearing on a GH1,  I had a no bearing problem a year or so
ago on the same model, same vintage. After measuring the string angles with
a compound gauge, I discovered that the back scale length was slopeing
upwards. Dial bearing gauges can fool you with this type of fault, since
they measure net bearing
The fault was traced to an inner to outer rim separation. Look at the rim
very carefully with plenty of good light. see if you can notice a very
slight step between the two rims. The two rim joint is clearly noticable,
so see if you can find any gaps with a thin spatula.
Talk to Ron.G. I'm sure he would be helpfull. In my case he extended the
warranty for the customer.
IF this is the cause, you will have to destring, and remove the plate to
epoxy the two rims together. I have encountered this fault once before, on
a no name cheap brand piano.
The challenge was making up various clamping blocks, to get the rims
clamped together. After the epoxy cured, I doweled the two rims every 8"
(maple dowels) or so, through out the problem area.
Both pianos had the problem in the octave 5/6  curved area of the rim.
Good hunting.
Roger
 



At 09:09 PM 09/03/00 -0600, you wrote:
>Dear fellow techies,
>
>Patient:		Yamaha GH1, 14 yrs old.
>
>Condition:	Treble bridge delaminating from soundboard and soundboard
>delaminating from rib #2 & 3 (approx. C5 - G6).  Downbearing barely
>detectable at all points along bridges.
>
>Symptoms:		None really!  Tone is relatively even throughout the scale,
>with good sustain.  No dead spots, buzzes or rattles.
>
>I presented the client with the following options:
>
>1.	Do nothing.  She enjoys the piano and apart from the obvious untoward
>appearance, the piano sounds pretty much the way a GH1 normally sounds.
>
>2.	Reduce tension across the scale and remove top 3 octaves of strings,
>use various wedging, clamping, screwing, gluing and or sorcery
>techniques to reunite the delaminated portions of
>bridge/soundboard/ribs.  The worry here is that this may result in a net
>reduction in the already barely detectable downbearing.
>
>3.	Put newfound soundboard replacement savvy (re: Brandon
>University/Bolduc soundboard seminar) into practice and slide a new
>board into place.
>
>Anyone ever see this condition on a Yamaha piano before?  Anything to
>add to the above options?
>
>Best regards to all!
>
>Stan Kroeker
>Registered Piano Technician
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505