D70 / Roland repair

[Martin Czech]

> Noise is caused by breakdown of laminations on high voltage transformer
> for the EL backlight.  New transformers aren't cheap, and sometimes
> hard to locate.  (most vendors have a minimum order)  Mine has actually
> gotten better over time, wierd huh?  While the key contacts do wear
> out over time, I have only had to replace one plastic key contact strip.
> It was due to a faulty diode in the matrix.  If you are having that
> much trouble, and have not replaced any of the assembly before, I suggest
> giving it a try.  The plastic contact strips are around $30 each (from
> a friendly service center anyway) and are used in a number of Roland
> synths.
> 
Thank you very much ! 
Please let me post it also to the list.

So it is the transformer.
Let's see, if I can get a Roland spare part.

Contacts: I've changed the grey rubber things 3 times! No way, Roland
representatives at the Frankfurt Music fair (tech guys, no tie wearing
guys ;->) said to me that this is a faulty construction principle,
the rubber cussions work like a vacuum pump and thus suck any dust into
the contact area. The remedy was to seal the cussions (which won't work
either, since the air must have a way out!!).  There are only two ways:

Trashbin or some other contact principle. That's why I ask about matrix
features etc. Perhaps I try the hall sensor idea, but they take 5mA each,
76 x 2 x 5mA is 760mA. The PSU won't give that much current.  OTOH I
could try reed magnetic contact (glass-sealed). This should work.  Do you
expect any trouble by the near zero resistance of these reed contacts ?

m.c.