Disklavier

Hello J. Youung

 The first problem could be easily fixed!! Have someone or yourself
take the screen off the AMP unit and push all of the ferrite donuts
inwards so that they do not touch the mesh, use tie wraps if necessary
to keep them off the mesh. Problem solved!!

 The second problem could be the Transformer inside the AMP unit that
feeds AC to the FU board. First, listen for the hum and try to locate
where you hear it the loudest. If you hear it by the Jack board then,
surely it's the Transformer. Explanation of transforemer noise. 

Transformers have tightly wound wire that some maybe not so tight and
become noisy as they bonce off each other when the ac field changes
polarity. 

 There are a couple of remedies!!

 1- Replace the transformer and hope that the other isn't as noisy!
 2- My favorite solution. Qdope-polystyrene-. Removing the transformer
                           and coating the windings with this stuff-2
coats ought 
to do it, let dry between coats-, will seal the windings, wedge itself
bwtween the windings and stop the noise. 

 Sometimes the noise maybe from the small transformers on the
Switching power supply-called the PWB board-and, almost the same
priciple above applies except, replace PWB or Qdope.

 I hope this helps!

DKVTECH1AB
--- In disklavier@yahoogroups.com, "FrJJY" <frjjy@y...> wrote:
> 
> There are actually two noises.  The main noise comes from within the 
> amp box somewhere.  The second noise is as you described:  a 
> vibration caused my the wire mesh and other metal surroundings.  I 
> can quiet the second, but not the main source.  This is a very 
> intermittent problem - happens about one hour for every five of 
> use.  Any other ideas would be greatly appreciated.
> 
> J. Young
> 
> --- In disklavier@yahoogroups.com, "dkvtech1ab" <fatcheson@a...> 
> wrote:
> > 
> > Hello J. Young
> > 
> >  Is it a HUM or is it an occasional rattle-a vibrating sound that
> > maybe mistaken to be a HUM-.? When you hear the HUM which is 
> comming
> > from the AMP unit underneath the piano, simply go underneath and 
> touch
> > the mesh that covers the amp, see if you can make it change. 
> Reason?
> > These units have Hi frequency shunts-shunt being used loosely to 
> make
> > a point- that are like litlle donuts in which the wires are wrapped
> > and cancels RF. Now, at times when the distance between the mesh 
> and
> > the shunts are just far enough but close enough to move away and 
> come
> > close just as the field is changing polarities, you will hear a 
> rattle
> > type hum from the AMP but not from the speakers. Same principle as 
> a
> > voice coil just not musical!!!
> > 
> > I hope this helps!!  
> > 
> > DKV1AB
> > --- In disklavier@yahoogroups.com, "FrJJY" <frjjy@y...> wrote:
> > > 
> > > I have a new DC1A with an intermittent problem:  There is 
> > > occasionally a hum that comes from the amplifier - perhaps the 
> power 
> > > supply.  The noise does not come through the speakers but comes 
> > > directly from the amplifier box.  Has anyone else had this 
> problem?  
> > > Unfortunately, the problem disappeared when my tech arrived, but 
> of 
> > > course, reappeared after he left.  Any solutions?
> > > 
> > > Thanks.
> > > 
> > > J. Young