Re: Re: K5 distorted output from patches using Source-2

Wow, thanks for all that info!

--- Antoine Deschênes <antdes45-FFYn/[email protected]> wrote:

> Hi,
> 
> some things that might help you:
> 
> Datasheet is here, no need to post it:
> http://focus.ti.com/lit/ds/symlink/pcm55.pdf
> Product Page:
>
http://focus.ti.com/docs/prod/folders/print/pcm55.html
> 
> Texas Instruments still produces the DAC, on the
> product page you can
> see that Arrow and Rochester Electronics have some
> in stock.
> 
> As you might have guessed, one DAC outputs S1
> sounds, and the other outputs S2.
> 
> Cold solder joints are common in this synth. In the
> first place, I'll
> suggest you to rework all the solders on the PSU
> regulator board. A
> lot of them fail.
> 
> The noise comes from the demultiplexing switches,
> the thousands of
> opamps placed after the DAC as well as the VCAs.
> 
> Here's the diagram (what I remember) :
> DACs ->
> demux switches (one chip per DAC divides the mono
> signal in 4
> different ones) ->
> Sample & Hold circuit ->
> S1 CH1-4 & S2 CH1-4 individual mixing (using high
> value resistors to
> prevent feedback from other channels in the S&H
> circuit, adds noise)
> ->
> VCAs (specs show they're quite noisy)->
> Opamp Buffers ->
> CH1-4 outputs.
> 
> The MIX and headphones outputs are connected to the
> last buffer stage
> outputs, mix the signal and go through one more
> buffer.
> 
> I was thinking of experimenting with the output
> stage by connecting
> two PGA4311s right at the output of the S&H opamps,
> and mix S1&S2
> after the PGAs to see if noise levels would improve.
> I just lack a bit
> of time to build the required stuff to program a PIC
> to control the
> PGA chips.
> 
> Your DAC might have a problem, but since there are a
> lot of external
> adjustments, it would be a good idea to check the
> components around
> the DAC first.
> 
> Cheers,
> Antoine
> 
> 2008/7/14 narfman96 <narfman96-/[email protected]>:
> > The balance only controls the volume for S1 and
> S2. If S1 is all the
> > way down S2 is cranked. Other than the DDA
> envelope (oh yeah the DHG
> > levels too) ahhh, where can S2 be turned down to
> sublight.
> >
> > The aftertouch was easy. There's 2 pots on the
> backside of the MI-004
> > board they say Gain (VR1) and Offset (VR2) on
> them. Open Midi-Ox and
> > watch the pressure change the values for
> aftertouch from 00 to F7.
> > Adjust these pots to get the best performance for
> your preferences.
> > Offset is where it starts to kick in. Then the
> gain adjusts how
> > quickly F7 cranks in. I like a smooth contollable
> range that doesn't
> > rip my tendons out.... That's why I can tell the
> notes from G3 to D4
> > in this K5 aren't as responsive as the rest.
> >
> > Whoohoo!!! I'm talking to Kawai about the Service
> Manual. They are
> > soooo gooood in this day and age of crapping on us
> hardware guys.
> > Oops did I say e-mu? Awww darn! Dirty bird!! I
> want my money back!!!
> >
> > Anyway the manual should be on its way....  Fran
> >
> > --- In [email protected], James Bong
> <jamesbong@...> wrote:
> >>
> >> How does it sound if you turn S1 all the way
> down, and
> >> start turning up S2? Same distortion?
> >>
> >> Oh, and where was the after-touch adjustment? I'm
> >> always afraid I'm going to tip my stand over when
> I'm
> >> using after touch modulation!
> >>
> >> James
> >> --- narfman96 <narfman96@...> wrote:
> >>
> >> > Yes I do have a scope I just haven't gotten
> that far
> >> > yet. Yesterday I
> >> > rebuilt the keyboard. This synth has a nice
> action
> >> > when it's all
> >> > greased up and triggers every note. I found the
> >> > aftertouch
> >> > adjustments and got it more sensitive than the
> key
> >> > bending tipping
> >> > over the stand mode it was originally set for.
> The
> >> > aftertouch strip
> >> > has a few spots that are less sensitive but hey
> it's
> >> > a beast....
> >> >
> >> > If it will help I can post the DAC's datasheet
> here
> >> > in the files
> >> > section so you can see what weird output
> >> > configurations it can have.
> >> > Either current or voltage outputs can be used.
> There
> >> > isn't any pot
> >> > for the offset zero. Also it seems like Kawai
> >> > doesn't use much of the
> >> > gain that's available. Maybe that's why it's so
> >> > noisy.
> >> >
> >> > The patches sound like they should if I turn
> the
> >> > balance so S2 is off
> >> > (-31). Except of course they're thin and
> lifeless
> >> > without the other
> >> > voice mixed in. I saved a bank that way so I
> could
> >> > check out the
> >> > keyboard. I can see where some of the noise
> comes
> >> > from. The high
> >> > frequency response goes way out there. Most of
> these
> >> > 80's and 90's
> >> > synths have low pass filters. This thing sounds
> wide
> >> > open on top end!
> >> > Probably so you can hear the 128 harmonics in
> all
> >> > their glory.
> >> >
> >> > Hopefully I won't be beat when I get home from
> work
> >> > so I can play
> >> > around with this some more. Still haven't heard
> from
> >> > Kawai yet about
> >> > the schematics. Also they always have me sign
> their
> >> > non-disclosure
> >> > form so I'm leery about openly posting them in
> the
> >> > group. Of course
> >> > helpful individuals are a different story.
> Right???
> >> >
> >> > Fran
> >> >
> >> > --- In [email protected], James Bong
> >> > <jamesbong@> wrote:
> >> > >
> >> > > You wouldn't happen to have an oscilloscope
> to
> >> > verify
> >> > > that the output of this chip is actual
> problem, do
> >> > > you?
> >> > >
> >> > > If you do get the schematics, could you
> possibly
> >> > get
> >> > > them scanned to share with the rest of us?
> >> > >
> >> > > James
> >> > >
> >> > > --- narfman96 <narfman96@> wrote:
> >> > >
> >> > > > I resoldered everything involved in this
> part of
> >> > the
> >> > > > circuit. There
> >> > > > is a feedback resistor on the DAC for the
> audio
> >> > > > output. This measures
> >> > > > 6.8k same as the working one. Maybe tonight
> I'll
> >> > try
> >> > > > lowering this
> >> > > > value to see if the gain decreases.
> >> > > >
> >> > > > I'm not having much luck finding a PCM55HP
> DAC.
> >> > > > Digikey lists it for
> >> > > > $38.50 with a long, long lead time... Crap!
> >> > Anyone
> >> > > > know of a source?
> >> > > >
> >> > > > Hopefully Kawai gets back to me today about
> the
> >> > > > schematic.
> >> > > >
> >> > > > Thanks, Fran
> >> > > >
> >> > > > --- In [email protected], James Bong
> >> > > > <jamesbong@> wrote:
> >> > > > >
> >> > > > > Does this chip have a bias circuit to set
> the
> >> > > > min/max
> >> > > > > output voltage scale? It could be
> something as
> >> > > > simple
> >> > > > > as a cold solder joint finally loosing
> contact
> >> > and
> >> > > > > changing the bias. I'd check/re-solder
> the
> >> > solder
> >> > > > > joints to everything connected to the
> chip,
> >> > and
> >> > > > the
> >> > > > > chip it's self.
> >> > > > >
> >> > > > > James
> >> > > >
> >> > > >
> >> > >
> >> >
> >> >
> >> >
> >>
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> 
> 
> 
> -- 
> Antoine Deschênes
> 


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