Yamaha PF 1000 piano , 2002

[N_Cook]

Do they want repairers to use the included ,single, off-centre steel rod
prop, when the top is open , to slip out of the next to non existant holding
position on the floppy drive housing , so they do fatal damage when the
whole wooden top with main pcb and display etc, crashes down? A bit of a
workup disconnecting wiring looms and screening cover but a hell of a lot
safer for collateral damage and personal safety, totally removing the top
section.

 

[N_Cook]

2 of the keys are sticking, because the plastic has warped with time or
temperature. Instead of internal dimension of 18.7mm the underside open
width is now about 18.3mm where it abuts the static pillar and rubs against
it. Any recognised safe method of locally heating or something that will
accurately realign the plastic and retain reformed shape? the throw on one
side is likely different to the other side so needs taking into account.

 

[N_Cook]

I have tried heating deformed keys with a hot air gun, and found it very
difficult. If you are very careful you can just about pull things into a
different shape if it is fouling something, but I found heating of a large
area often reults in the plastic shrinking and the key becoming too short to
fit/work at all. Different plastics may have different properties though,
these were old Roland keys no longer available.

Also there seems to be a fine tolerance between getting the plastic pliable
enough to remould, and so pliable it runs into a goo, which you have no hope
of moulding back to shape. A temperature controlled oven is probably your
best bet,k and you will need a lot of practice on something disposible
first.



Gareth.

In the next hour I will tackle this. Have something like a 30 amp ceramic
connector block with the metal part removed and hole large enough to take a
brass cased thermometer wedged inside with key laid sideways on a large PTFE
slab. This ceramic small enough to go inside plastic recess and only touch
the one face most deformed. Starting at 60 degrees from hot air I will
increase by 10 deg steps , measuring with Vernier each time.

 

[N_Cook]

I had previously swapped the erroneous keys with relatively unused top
actave ones , showing it was a key problem , not guide pillar or pivot
problem. They still stick in new position but if I make matters worse its
not too disastrous

 

[N_Cook]

Oh, and boiling water is not hot enough unfortunately.



Gareth.

Just short

Using my ceramic block method, melting point around 105 to 120 degree C.
Opened up one side about .1mm and worse sticking although the "correct" side
to compensate , but more convincing now a rotation problem along the key
axis. I'd just allowed the key to rotate more. Hopefully such slight melting
will be recoverable now real reason of failure found.
I'd noticed these keys removed and replaced easier , and didn't seat well,
than the good keys so now assumed a wear problem at the pivot end. Found
some ball bearings to take measurements from good and bad key recesses with
Vernier callipers. Cleaning off the grease inside , a part of the pivot end
housing broke away. I've previously repaired Yamaha keys on a different
piano that had been kicked over - moulding repacement sections as original
flaked off parts missing in the original incident.
This one must have been cracked but holding together enough to use /remove/
replace but not locally clean. The other one on very close inspection a
short crack visible and stressing remainder opened up more of the crack.
Will capilliary superglue and reinforce with "hot melt soldering" in the non
contact areas of both key breaks.
Crack on one face allowing the key to rotate on the pivot slightly, then
rubbing action at the play end.

 

[N_Cook]

IMHO you'd do a lot better buying new keys and charging the customer for
them, but whatever floats your boat I suppose.



Gareth.

Both now working better than the worst of all the remaining good keys.
I consider I've failed if I have to rely on main agents for anything. It
means I've copped out and not learned anything along the way.

These 2 and IIRC the previous Yamaha keys have failed where there is ,
AFAIK, unnecessary necking at the pivot end and the narrower of the rearmost
2 vertical flanges has broken away.

 

[N_Cook]

IMHO you'd do a lot better buying new keys and charging the customer for
them, but whatever floats your boat I suppose.



Gareth.

Both now working better than the worst of all the remaining good keys.
I consider I've failed if I have to rely on main agents for anything. It
means I've copped out, wasted time on ordering and delivery process, and not
learned anything along the way. Especially such as these great lumps that I
can only work on and temporary storage, safely without getting a strained
back, as the 2 main sections , on end vertically, strapped to the wall.

These 2 and IIRC the previous Yamaha keys have failed where there is ,
AFAIK, unnecessary necking at the pivot end and the narrower of the rearmost
2 vertical flanges has broken away.

 

[N_Cook]

Back together, no screws left over , and working all functions as far as I
can tell. Amplifier no longer making nasty noises and all keys moving and
aligned properly.