Disklavier

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

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

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

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

Hello everyone

 Seems to me there are 2 different issues here. 

1- J. Young's Disklavier Hum is being emmited by the AMP unit and not
the speakers.


 What I'd like to know is;

 A- is the Hum heard at the speakers always there?
 B- Does it increase when the Treble knob is turned up?
 C- Is the HUM very loud when connected to an external sound system
even if the voulume in the amp-Disklavier- is turned down completely.
 D-Have you tried a different AC outlet even if it takes a 50 foot AC
cord?
 
 My 2 cents...Most electronic audio instruments will emmit hum when
certain criteria is encountered. Hum will be more noticeable when 2
electronic sound systems are put together. 
 
Possible reasons

 1- UL requires grounding and threfore, it will be a path for most
source of noises. When 2 systems are put together, their wireing has
resistance thus, creating at X and Y points a potential difference
that by it's nature developes a voltage across this resistance. What
you get is noise from the difference.

 2- Noise can be developed someplace else in the house specially when
Blenders, Refrigerators, just about anything with a motor in the same
AC Line will cause Inductive Reactance.

 To test if the Disklavier's noise is being generated some place else
in the AC line.

A- Use a Ground puller-for testing purposes only, remove puller after
finding the desired information-and listen to the speakers with the EQ
BASS and TREBLE set to 12 O'Clock. If the Noise is gone or greatly
diminished then, part or most of that noise is at the AC level.

Possible solution..Use a dedicated AC line or an AC Conditioner.

B-If the noise does not decrease and instead it may increase then, it
could be a ripple factor at the power supply.

Possible solution..New power supply
 
 Most of the time, the problem is at the  AC Line level.

 I hope this helps!!

 dkvtech1ab

 

--- In disklavier@yahoogroups.com, "Jerry Dutcher" <gldutcher@e...> wrote:
> When I got my new MkIII Disklavier last year I noticed the same
thing.  I have a very audible 60 Hz hum coming out my DKV speakers --
not outrageous, but definitely audible.  When I connected the aux
outputs to an amplifier it WAS outrageous.  The aux outputs are quite
low level -- not at all full line-level signals.  Thus a modest amount
of 60 Hz hum on these lines will be amplified disproportionately.  I
spoke to Bill Brandom at Yamaha -- he was familiar with the problem
and recommended the use of a mixer/preamp with the aux outputs.  I
picked up such a unit at my local Guitar Center outlet, and it brought
the hum down to a tolerable level.  I still hear the hum very clearly,
but frankly most casual listeners don't notice it.
> 
> My conclusion is that while Yamaha did a fantastic engineering job
on the basic DKV instrument, the electronics design did not receive
the same degree of attention.  Yamaha has in their corporation a world
class audio electronics arm, and the design techniques for minimizing
and eliminating line frequency hum are well understood.  It is beyond
my understanding why they did not apply some of this knowledge to the
DKV electronics design.  Proper grounding, filtering and shielding
throughout could eliminate this problem, but it would take an
electronics redesign to accomplish it.  
> 
> Jerry Dutcher
> 
> ----- Original Message ----- 
>   From: J D 
>   To: disklavier@yahoogroups.com 
>   Sent: Tuesday, November 23, 2004 5:05 PM
>   Subject: RE: [disklavier] hum from amplifier
> 
> 
>   I have a similar problem with my DC7A.  It is more noticeable when
I have recorded from the auxiliary outputs.  I will be interested in
knowing what you guys suggest.
> 
>   Thanks,
> 
>   John W
> 
> 
> 
> 
> 
>   >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 
>   > 
>   > 
>   > 
> 
> 
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If there is a Hum/Noise comming from within the AMP unit, I am still 
convinced that the only thing that could vibrate and emmit oscillation 
are with coils. IE; Main transformer and the Small transformers on the 
Power supply[pwb board]. I have had to dope[Q Dope] many xformers in 
the past to mute them. Maybe a call to a technician that has 
background in this type of problems would be able to help.

DKVTECH

 
--- 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