K5synth

Antdes,
I just wanted to compare some notes on the schems.  I have not had a
chance to dig too deep yet but I want to see if you reached some of
the same conclusions I have on some of the notation...
1) Many connectors have both "AG" and "DG".  Based on my quick look
this seems to mean Analog Ground (AG) and Digital Ground (DG).  Do you
agree?  In general something like "+A6" means "analog 6 Volts"

2) It looks like the schems have a slightly different symbol for the
AG and DG.  The AG ground looks like a horizontal line with three
vertical swipes under it where as the DG has a more traditional symbol
for ground.  Do you agree?

The first thing I want to try is to directly connect all of the AG and
DG cables to a single ground at the same place.  By any chance, have
you tried that yet?  

Anyway, I think I have decoded the schems but I never hurts to compare
notes. Thanks. 
   

--- In k5synth@yahoogroups.com, Antoine Deschênes <antdes45@n...> wrote:
> Mine's not at -65 but at -47 dB with the TL072.
> 
> nelsonj_sce@y... a écrit:
> 
> >
> > I got the schems yesterday and I will take a look at the ground
issue.   
> > Although all grounds will eventually get to a single point, one idea
> > is to make sure the D and A get to the same ground at the same time -
> > that is make sure there is no path between the A and D grounds.
> > Anyway, I will try to look at the schems this weekend.
> >
> > I also just upgraded to OS1.2.  I am a bit disappointed that the
> > Kfuenf editor still does not work for me.  Oh well, more on that in my
> > next post. 
> >
> > Also, I hooked up my J-station to the K5.  The J-station has a very
> > good noise gate, as well as delay+reverb+chorus(ect).  I have to crank
> > the noise gate up to about 65 to kill the line noise.  But the K5
> > sounds great through this unit and I recommend it if you happen to
> > have a J-station around.
> > --- In k5synth@yahoogroups.com, "antdes45dragonmaster" <antdes45@n...>
> > wrote:
> > >
> > > Buzzing in rear out is signal ground noise, all pcbs have sepparate
> > > analog grounds to PSU but linked together on the psu.
> > >
> > > --- In k5synth@yahoogroups.com, "nelsonj_sce" <nelsonj_sce@y...>
> > > wrote:
> > > >
> > > > Antdes,
> > > > Good information in the note below.  It sounds like the good
news is
> > > > that the digital (D) and analog (A) have seperate grounds.  From
> > > > everything I have been reading that is good news.  If they had the
> > > > same ground on the same PCB we might be completely out of luck. 
> > > Today
> > > > I ordered the latest OS ROM and schematics from Kawai so
hopefully,
> > > > once I have the schems, I make more informed suggestions on how to
> > > > reduce the ground noise.
> > > >
> > > > I did read something today that said that, although you should
have
> > > > separate A and D grounding, ultimately both the A and D should be
> > > > grounded at the same point.  Otherwise, the D might inject
noise in
> > > to
> > > > the A ground.  Based on your note, this might be just what is
going
> > > on
> > > > in the K5. 
> > > >
> > > > Based on this observation, one thing to try would be to take the D
> > > > ground off of the power supply board and connect that ground
> > > directly
> > > > to the A ground on the transformer.  We need to make sure the
power
> > > > supply board is still fully grounded even if we remove the D
ground,
> > > > but you should be able to check the schem and see if it looks like
> > > > this is an easy move.
> > > >
> > > > Anyway I don't want to do anything too fancy until I look at the
> > > > schems, but if it looks safe, this is the first thing I want to
> > > try.
> > > > (Or if you feel adventurous you could try it and tell me if it
> > > works!)
> > > >
> > > > Thanks for the note and let me know if you find anything else out.
> > > >
> > > >       
> > > >
> > > >
> > > >
> > > > --- In k5synth@yahoogroups.com, "antdes45dragonmaster"
> > > <antdes45@n...>
> > > > wrote:
> > > > > Digital Ground is plugged to one bridge's negative pole and
> > > analog to
> > > > > 0v line of the transformer(Black wire). I know it's a noisy
ground
> > > > > because when I transfer MIDI between K5 and computer, I hear
some
> > > low
> > > > > volume beeps in the noise, and my intermittent inverter
whines(Is
> > > on
> > > > > DGround) in the headphones when it wants. I looked at the
> > > schemes, and
> > > > > every different PCB's DGrounds are plugged together on the PSU
> > > > > mainboard, but are going to it thru different wires.(Same for
> > > > > AGround). Problem is I don't remember how to filter ground.
> > > Something
> > > > > to try. Also, when I unplug the brown socketed black bus wire
> > > going to
> > > > > outputs board, there is no signal from the headphones, but still
> > > > > noise. So it's not coming from the opamps(Headphones noise).
> > > Might be
> > > > > that the LM386's ground has no filter. While for the rear
outputs
> > > > > noise, the opamps might be too noisy(-45dB with some TL072
> > > instead of
> > > > > some TL062, which might have not changed anything noise talking,
> > > using
> > > > > some OPA????, don't remember which, will have to re-find the
name
> > > on
> > > > > DIYAudio, might be a lot less noisy, because a signal passing 4
> > > times
> > > > > in pretty noisy OpAmps in series might not be really good).
> > > > >
> > > > > --- In k5synth@yahoogroups.com, "nelsonj_sce" <nelsonj_sce@y...>
> > > wrote:
> > > > > > It looks like you have already changed out the op-amps and
> > > found that
> > > > > > the noise is still there.  Have you tried anythink to fix the
> > > noisy
> > > > > > ground?  Is it that the digital and analog all share the same
> > > ground?
> > > > > > Is there a way to "split" the ground or add a new ground plane
> > > and
> > > > > > reroute say the digital chips to the new ground plane? 
Are all
> > > the
> > > > > > analog parts on a single board so that we could just cut the
> > > ground to
> > > > > > that board and then wire up a new, "independent" ground?  Are
> > > there
> > > > > > just a few key digital parts that are creating the noise that
> > > can be
> > > > > > rerouted to a seperate ground plane?
> > > > > >
> > > > > > Has anyone at Kawai told you how to solve this problem?  Even
> > > if I can
> > > > > > get a hold of the schematics, if Kawai or others can
identify a
> > > few
> > > > > > key components it should not be that hard to create a seperate
> > > ground
> > > > > > for those parts.
> > > > > >
> > > > > > Any thoughts?
> > > > > >
> > > > > > --- In k5synth@yahoogroups.com, Antoine Deschênes
> > > <antdes45@n...>
> > > > wrote:
> > > > > > > The LM386 doesn't produce any noise. Even if you unplug the
> > > signal
> > > > > > there
> > > > > > > will still be some. Sctually the problem is a noisy ground.
> > > It's
> > > > > > sharing
> > > > > > > the same ground for all the board(s).
> > > > > > >
> > > > > > > nelsonj_sce@y... a écrit:
> > > > > > >
> > > > > > > > Here is the latest, it is good news.
> > > > > > > >
> > > > > > > > Today I got my parts for DigiKey.  As below I replaced my
> > > > backlight
> > > > > > > > with a blue backlight from nightlaunch.  It worked with my
> > > > stock K5
> > > > > > > > inverter.  However, my stock inverter was very flakey,
even
> > > > after I
> > > > > > > > did the resolder job so I decided to replace the stock
> > > > inverter with
> > > > > > > > the DigiKey part.  (Digikey part #289-1032-ND).  The good
> > > news
> > > > > is that
> > > > > > > > inverter works (even though it is only about 95V @ about
> > > > 550Hz).  It
> > > > > > > > is a slightly different color than before, but it still
> > > looks
> > > > great.
> > > > > > > > Also- THERE IS VIRTUALLY NO HUM!
> > > > > > > >
> > > > > > > > The only warning is the Digikey part is not the exact same
> > > size
> > > > > as the
> > > > > > > > original inverter - it is a bit smaller in footprint and a
> > > lot
> > > > > > > > shorter.  The stock inverter has only three connections
> > > (in -
> > > > out -
> > > > > > > > ground) and the new inverter has a fourth pin for
mounting.
> > > > Because
> > > > > > > > the part is smaller, I used the original hole for
> > > the "out", but
> > > > > I had
> > > > > > > > to wire up jumpers to the "ground" and the "in" - not
a big
> > > > deal but
> > > > > > > > it is some extra work  - and you don't want to see
pictures
> > > of
> > > > > my ugly
> > > > > > > > job.  :).  But so far so good.
> > > > > > > >
> > > > > > > > Also, I did the 147K resistor hack and it seems to
have gone
> > > > > well.  My
> > > > > > > > K5 is a louder, but the headphones have even more noise
> > > now.
> > > > I have
> > > > > > > > been looking things over and I think the headphone
noise is
> > > > because
> > > > > > > > they use a cheap LM386 op-amp and a bad overall design for
> > > the
> > > > > > > > headphone amp.  I am trying to see if I can replace this
> > > with a
> > > > > better
> > > > > > > > op-amp, otherwise I think the only good solution is to
just
> > > bypass
> > > > > > > > their circuit completely and make a better headphone
amp and
> > > > wire it
> > > > > > > > up to the K5.
> > > > > > > >
> > > > > > > > Anyway, again the good news is that for less than $30
> > > > delivered you
> > > > > > > > can get nightlaunch backlight and a Digikey inverter and
> > > have
> > > > a new
> > > > > > > > backlight that does not hum!  :) 
> > > > > > > >
> > > > > > > > Now for the headphone amp...
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > --- In k5synth@yahoogroups.com, "nelsonj_sce"
> > > <nelsonj_sce@y...>
> > > > > > wrote:
> > > > > > > > > Update:
> > > > > > > > > Well today I ordered a new inverter from
> > > www.DigiKey.com.  I
> > > > > > found an
> > > > > > > > > inverter that looks like it will do the job - for those
> > > > interested
> > > > > > > > it is:
> > > > > > > > >
> > > > > > > > > Digikey part #      289-1032-ND  and it only cost
$11.90 -
> > >  not
> > > > > bad.
> > > > > > > > >
> > > > > > > > > I am not sure if it will fit exactly in the same
slots as
> > > the
> > > > > > original
> > > > > > > > > inverter so it might require some additional wiring.
> > > > > > > > >
> > > > > > > > > Anyway, I had my K5 open to look at the power supply to
> > > plan
> > > > > the new
> > > > > > > > > inverter install when my K5 started "humming", and guess
> > > what,
> > > > > I now
> > > > > > > > > have a beautiful blue backlight.  It looks great, a very
> > > cool
> > > > > blue.
> > > > > > > > > So it appears my inverter was not bad, but it just
has bad
> > > > solder
> > > > > > > > > joints.  It is working for now but tomorrow I will
likely
> > > take
> > > > > > out the
> > > > > > > > > board and redo all the solder joints.
> > > > > > > > >
> > > > > > > > > Just some additional info I learned in researching
> > > > backlights and
> > > > > > > > > inverters.  The "brightness" of the backlight is a
> > > function
> > > > of the
> > > > > > > > > voltage and frequency applied to the backlight.  It
> > > appears one
> > > > > > has a
> > > > > > > > > lot of flexibility in selecting the inverter output
> > > voltage and
> > > > > > freq.
> > > > > > > > > For example, nightlauch says you can "test" the
backlight
> > > by
> > > > > > plugging
> > > > > > > > > it directly in to a wall socket (120V AC @ 60 Hz here in
> > > the
> > > > > > US)!  The
> > > > > > > > > higher the voltage and freq the brighter the backlight. 
> > > > > > However, the
> > > > > > > > > backlight will "burn out" quicker the higher the freq. 
> > > So there
> > > > > > is a
> > > > > > > > > trade off, high freq = bright but shorter life.
> > > > > > > > >
> > > > > > > > > Right now my stock inverter is putting out about 102V @
> > > 380
> > > > Hz.  I
> > > > > > > > > think the inverter I ordered will put out about 95V
@ 540
> > > Hz and
> > > > > > > > > should work with a 3 - 6 V DC input.
> > > > > > > > >
> > > > > > > > > Next step, 147k resistors (also ordered from Digikey
> > > today).
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > --- In k5synth@yahoogroups.com, "nelsonj_sce"
> > > <nelsonj_sce@y...>
> > > > > > wrote:
> > > > > > > > > > Well I replaced my backlight with one I ordered from
> > > > > > > > > www.nightlaunch.com.
> > > > > > > > > >
> > > > > > > > > > It took less than two weeks from when I ordered
and the
> > > > > parts look
> > > > > > > > > good.
> > > > > > > > > >
> > > > > > > > > > Good news/bad news though on my backlight.
> > > > > > > > > >
> > > > > > > > > > The good news:  I had no problems removing the LCD,
> > > taking out
> > > > > > the old
> > > > > > > > > > backlight and sliding in the new backlight.  The new
> > > light has
> > > > > > some
> > > > > > > > > > wires and a plastic "tab" that kind of gets in the
way,
> > > so I
> > > > > > soldered
> > > > > > > > > > the backlight wires to where the wires connect to the
> > > LCD
> > > > board.
> > > > > > > > > > Hint:You have to cut the new backlight to size, so
make
> > > the
> > > > > > backlight
> > > > > > > > > > a little longer (say 1/4 inch) than the original
to make
> > > > things
> > > > > > > > easier.
> > > > > > > > > >
> > > > > > > > > > Bad news: My backlight does not work but I think my
> > > inverter
> > > > > > is the
> > > > > > > > > > problem.  I am only getting about 1/2 Volt at the
> > > output of my
> > > > > > > > > > inverter, and I am supposed to get 120V @400Hz if I
> > > > > understand the
> > > > > > > > > > part correctly.  I tested my inverter before I did the
> > > > backlight
> > > > > > > > > > install and saw it had low voltage, but I was hoping
> > > that my
> > > > > > existing
> > > > > > > > > > "dead" backlight was causing the problem (i.e. it was
> > > > > shorted.) I
> > > > > > > > > > guess not because even with the new backlight I get
> > > very low
> > > > > > voltage.
> > > > > > > > > >
> > > > > > > > > > Anyway, it looks like I need to get an inverter. 
I can
> > > get an
> > > > > > > > > > inverter from nightlaunch for $17.99+s/h but it
needs 9V
> > > > DC.  I
> > > > > > > > > > understand the inverter in the K5 uses 5V DC.
> > > > > > > > > >
> > > > > > > > > > Q1: Does the K5 inverter use 5V DC?
> > > > > > > > > > Q2: If I measure the voltage on the two wires to the
> > > left
> > > > of the
> > > > > > > > > > inverter, should I get 120V if everything is working?
> > > (My
> > > > > > Fluke says
> > > > > > > > > > it is good <=1kHz)
> > > > > > > > > > Q2: Does anyone know where to get a compatible K5
> > > inverter
> > > > > and how
> > > > > > > > > > much it will cost?
> > > > > > > > > >
> > > > > > > > > > Thanks again for all the help.  This group is great.
> > > > > > > >
> > > > > > > >
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> 
> Antoine Deschênes /aka
>   -´¯`-¸-DragonMaster-¸-´¯`-
> http://thehotcom.deep-ice.com/
> Files: http://www.angelfire.com/ca7/hotcomcenter/