D70 / Roland repair

[Martin Czech]

Finally I've come to the conclusion that repairing the Roland style
keyboards with rubber contacts is pointless, it always helps for a few
days and then the trouble starts again. Roland representatives said to me
that the problem is known, but they couldn't make any reasonable proposal.

Does somebody know, how the Roland keyboard scanning systems work?
I mean it is obvious that there are two time delayed contacts per key.
What is the expected contact resistance? What are the levels at the contacts?
Would an open-drain do as replacement?

I want to use our HAL114 open drain sensors, they are cheap for me :->.

Does somebody know what causes the sqeeking noise (LCD-display).
Is it the background illumination ? Is there a transformer the
causes this noise by magnetostriction (sp?). WOuld could I do 
against this noise ?

m.c.