Antdes,
Ok, I still have more work to do but I did look more at the schems
while on a plane today. Some thoughts...
1) DO NOT simply remove the DG ground on the power supply and reroute
it to the AG (black transformer wire). If you do this the inverter
for the backlight (as well as several caps and part D6 WILL NOT BE
GROUNDED. Basically the DG does not terminate on MI-010, rather
MI-010 needs the connection <CN1> in order to be grounded. I am still
looking at things but it seems the main ground for the MI-003 &MI-004
comes from where they are screwed in to the K5 case.
2) Although I am not 100% sure, it appears that for some reason, on
board MI-004 the DG and AG are actually connected. Board MI-003 is
all digital so the ground is pure digital. If I am correct, and the
AG and DG grounds are not separated on MI-004, this may be the source
of the noisy ground. The bad news is that there is no quick way to
separate the grounds on MI-004.
3) Part U4 (the op-amp right after the VCA that we have both replaced)
has my attention. It has four inverting op-amps, where the "+" of
each amp is connected directly to the dirty ground. It is possible
that the dirty ground is basically injection noise to these amp.
I think we both have replaced this op-amp and it is now in a socket. I
plan on taking out the amp(this is a total hack but if it works I can
make it look nice later), and then bending connections 3, 5, 10, 12
(the grounds) out so that they do not connect to the socket/dirty
ground on board MI-004. Then, I will wire these connections directly
to the K5's case to try and get a clean ground.
4) If that does not help lower the noise, I am looking at lines g0-g7
that feed the op-amps U8 and U9. These are the only analog signal
lines that have Faraday shielding. These are low level lines early in
the analog signal chain. If nosie gets in to these lines, the nosie
will get amplified in each of the following amp stages. Perhaps there
is a way to improve the shielding on these lines or to change the
grounds related to these singal paths...but I have to think about how
to do it.
Anyway, I will let you know what happens after I reground U4.
--- In k5synth@yahoogroups.com, antdes45@n... wrote:
> That's it, AG is analog ground, DG digital ground, +A6V dc analog
6v. . .
> The kind of fork for the analog ground is an other sign for ground,
maybe they mean different connection places, as the fork like is used
for antenna too. But I think it's just a country/continent difference.
>
> "nelsonj_sce" <nelsonj_sce@y...> wrote:
>
> >
> >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.
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > > Yahoo! Groups Sponsor
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> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> ><http://us.ard.yahoo.com/SIG=129jk20o5/M=273541
.4247512.5496808.224846
> >> > > 7/D=g=
> >> > > > > =
> >> > > > > >
> >> > > > >
> >> > > >
> >> > >
> >rplch/S=1705032144:HM/EXP=1095918198/A=2061551/
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> >> > > ://la=
> >> > > > > u=
> >> > > > > > nch.yahoo.com/artist/videos.asp?artistID=1001301>
> >> > > > > >
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > > > >
> >> > > > > >
> >> > > >
> >-----------------------------------------------
---------------------
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> >> > > > > > >
> >> > > > > > > --
> >> > > > > > > antdes45@n...
> >> >
> >> >
> >> >
> >> >
> >> > Yahoo! Groups Sponsor
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> >> --
> >>
> >> Antoine Deschênes /aka
> >> -´¯`-¸-DragonMaster-¸-´¯`-
> >> http://thehotcom.deep-ice.com/
> >> Files: http://www.angelfire.com/ca7/hotcomcenter/
> >
> >
> >
> >
>
>
> --
> Antoine Deschênes
> aka DragonMaster
> http://thehotcom.deep-ice.com/
> Files:http://angelfire.com/ca7/hotcomcenter/
>
>
> __________________________________________________________________
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Re: Notes on Schems...
2004-10-16 by nelsonj_sce