Display noise (was K5000 warranty support)

[Bjarne Nillson]

>This can be very annoying indeed, and I remember how disapointed I was 
when I sold my "virtual analogue" D-50 (quiet) and bought a D-550 (high 
pitched noise) instead.
>I checked with Roland, they faxed me a copy of the PSU page from the 
service
>manual and told me that they have changed the display from the keyboard 
to the expander version of the D-50.
>The new display needed an external high AC supply voltage (might be 
around
>100V, don't remember exactly), and this was generated by an oscillator 
and
>a little transformer. High frequency, small transformer, law of 
physics, and
>law of economics ...
>I tried everything to get this transformer quiet, pieces of styrofoam,
>various
>types of glue, pieces of carpet, but I didn't get it quiet.
>Then I decided to replace the whole crappy circuit. The display would 
run on 50Hz AC as well, as long as the voltage was the same.

I had the wery same problem with my D550 i put the whole OSC
cirquit in sillicon and turned the frequency of the OSC down,
ofcourse the display went darker but went more silent.

BJ


______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com