Cgs synth

Dang! I forgot about a little boo-boo on the PCB. Link +15V to pin 1 of
the LM311 and you should be good to go.
It's not connected to anything right now... sorry!

Cheers,
Scott Deyo
The Bridechamber
contact@...
http://www.bridechamber.com
Jealous Edison Record Kompany
http://www.jealousedison.com

On Oct 15, 2008, at 2:21 AM, andrewlistmayer wrote:

> I just read through this old thread because I have a similar problem
> with my Bi-n-Tic. I can get a filter sweep out of the last 20% or so
> of the bandwidth knob, but the tuning knobs do nothing. This leads me
> to believe that the center frequency is stuck somewhere below the
> audio range. So, I check the oscillator section. I also have a slight
> amount of DC on pin6 of CA3140, so it isn't oscillating. I also have
> voltage on pin 2, which is supposed to be at 0. Then, I start at the
> beginning and try to figure out what is wrong. I can find no faults in
> the CV summing section, yet I only get between -.8 and barely above 0v
> depending on the coarse tune pot. Is this correct? Also, I am not
> getting +15 on pin 1 of the LM311 like it shows on the schematic. The
> datasheet tells me this is a ground pin, so I'm not sure how important
> this is. I'm using a PN4391 fet and I matched the G, S and D on the
> PCB with the pinout on the fairchild datasheet. One last thing to note
> is that I'm using the bridechamber PCB. I didn't know what to do about
> the 100k resistor marked with a star, so I installed, then removed it
> afterwards.
>
> I'm stumped at this point, so any hints would be greatly appreciated.
>
> --- In cgs_synth@yahoogroups.com, sasami@... wrote:
> >
> > Check your capacitor too. Make sure it is the right size. Make sure
> it is
> > actually soldered in - no bad joints, or not between the wrong
> holes. there
> > is a spare hole there to allow for different sizes. If you have the
> cap
> > between two the holes that are joined by the trackwork, it isn't
> going to work.
> >
> > Also note that the pin-outs of different FETs varies. If I use the
> 2n4091, I
> > need to install it "backwards" to the marking on the PCB.
> >
> > Ken
> >
> > >So, if the voltage on pin 2 & 3 is 0V and the 3140 gets it's
> > >powersupply, it should create some AC voltage on pin 6 ?
> > >I have only a DC voltage that varies between 0 & 0.86 VDC
> (depending
> > >on the position of the coarse frequency pot )
> > >
> > >thanks again for your help !
> > >steven
> > >
> > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >>
> > >> You should never see any voltage on pin 2 of the 3140 - it is a
> > >summing
> > >> node. It is a basic op-amp feedback loop. Yhe opamp devotes its
> > >entire time
> > >> truing to keep pins 2 and 3 at exactly the same voltage. As pin 3
> > >is 0v, pin
> > >> 2 will be 0v. The current through the point will of course vary
> as
> > >the
> > >> output of the op-amp fights the current drawn through the LM394
> > >(through the
> > >> integrating capacitor and through the FET during reset).
> > >>
> > >> Ken
> > >>
> > >> >hello,
> > >> >no luck so far, I've replaced the 2N4391 fet, but still no
> > >voltage
> > >> >on pin 2 of the ca3140. I've also measured with a scope to see
> > >what
> > >> >is exactly the output on pin 6 of the ca3140, and it shows only
> a
> > >dc
> > >> >voltage ( 0.86 V )
> > >> >
> > >> >any more clues ?
> > >> >many thanks in advance !
> > >> >steven
> > >> >
> > >> >--- In cgs_synth@yahoogroups.com, "stiebz" <theevaporizer@>
> wrote:
> > >> >>
> > >> >> hey,
> > >> >>
> > >> >> I used a 2n4391, I have no clue how I can check if it still is
> > >> >> working properly, so I'll try to replace this compontent to
> see
> > >if
> > >> >it
> > >> >> makes a difference.
> > >> >>
> > >> >> thanks,
> > >> >> steven
> > >> >>
> > >> >> --- In cgs_synth@yahoogroups.com, "bbluthang" <jumpswine@>
> > >wrote:
> > >> >> >
> > >> >> > Hi
> > >> >> > look at the FET, what kind are you using? right way around
> etc
> > >> >> > some FETS wont work in these ccts.
> > >> >> > Andrew
> > >> >> >
> > >> >> >
> > >> >> > --- In cgs_synth@yahoogroups.com, "stiebz" <theevaporizer@>
> > >> >wrote:
> > >> >> > >
> > >> >> > > unfortunately my bintic filter is still not working...
> > >> >> > > I've replaced the tl072, ca3140 and the lm394, but still
> > >the
> > >> >> > > oscillator part is not working as expected.
> > >> >> > > I've noticed that depending on the setting of the
> frequency
> > >> >> coarse
> > >> >> > > pot, I have different readings on the circuit.
> > >> >> > > I've added here a link to a part of the circuit diagram
> > >where
> > >> >> I've
> > >> >> > > indicated some measurements done in both minimum and
> > >maximum
> > >> >> > > position of the frequency coarse potmeter. I hope somebody
> > >can
> > >> >> give
> > >> >> > > me clue where more or less the problem should be with this
> > >> >data.
> > >> >> > > Thanks a lot in advance, you can find the drawing here :
> > >> >> > > http://users.telenet.be/theevaporizer/modular/bintic.GIF
> > >> >> > >
> > >> >> > > steven
> > >> >> > >
> > >> >> > >
> > >> >> > > --- In cgs_synth@yahoogroups.com, Romeo Fahl <rfahl@>
> wrote:
> > >> >> > > >
> > >> >> > > > one thing to keep in mind is that CA3140s are super
> > >delicate
> > >> >> ICs.
> > >> >> > > > They are very sensitive to static, but it wouldn't
> > >surprise
> > >> >me
> > >> >> if
> > >> >> > > > hooking up power in reverse was too much for it to
> handle.
> > >> >> > > >
> > >> >> > > > Romeo
> > >> >> > > >
> > >> >> > > >
> > >> >> > > > On Nov 4, 2006, at 6:08 AM, stiebz wrote:
> > >> >> > > >
> > >> >> > > > > No chips are hot ( and nothing smells burned )
> > >> >> > > > > The TL072 seems to working fine, output 7 follows the
> > >> >> frequency
> > >> >> > > > > settings, but on the CA3140 I always measure 0.56 V on
> > >pin
> > >> >2
> > >> >> and
> > >> >> > > 1.1
> > >> >> > > > > V on pin 6 regardless of the frequency setting. Would
> > >this
> > >> >> > > indicate
> > >> >> > > > > a faillure on the CA3140 or the LM394 ?
> > >> >> > > > > thanks !
> > >> >> > > > > steven
> > >> >> > > > >
> > >> >> > > > > --- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >> >> > > > > >
> > >> >> > > > > > Test #1 - feel if any chip is getting hot. If it is,
> > >> >> replace
> > >> >> > > it.
> > >> >> > > > > >
> > >> >> > > > > > Ken
> > >> >> > > > > >
> > >> >> > > > > > >when i wanted to test my bin-n-tic, i incidently
> > >> >switched
> > >> >> +
> > >> >> > > and -
> > >> >> > > > > > >power supply. after i fixed the problem, I have no
> > >sound
> > >> >> > > > > whatsoever.
> > >> >> > > > > > >I measured 1.1 volt between pin6 of the ca3140.
> > >> >> > > > > > >Is there any part(s) that is the most likely to be
> > >> >> damaged ?
> > >> >> > > > > > >thx,
> > >> >> > > > > > >steven
> > >> >> > > > > > >
> > >> >> > > > > > >--- In cgs_synth@yahoogroups.com, "kopernig"
> > >> ><6079smith@>
> > >> >> > > wrote:
> > >> >> > > > > > >>
> > >> >> > > > > > >> yes, i noticed the diode and put in a jumper...
> > >but
> > >> >> still no
> > >> >> > > > > joy. i
> > >> >> > > > > > >> don't have a scope (yet) but the voltage on pin
> > >six
> > >> >of
> > >> >> the
> > >> >> > > > > ca3140
> > >> >> > > > > > >is
> > >> >> > > > > > >> just under 1 volt. with an audio probe i can
> > >(barely)
> > >> >> hear
> > >> >> > > a cv
> > >> >> > > > > > >click.
> > >> >> > > > > > >> so the vco is not oscillating. i can't figure out
> > >why
> > >> >> the
> > >> >> > > 2n2
> > >> >> > > > > > >> capacitor seems to be shorted... there's no
> > >> >resistance
> > >> >> > > between
> > >> >> > > > > the
> > >> >> > > > > > >> source and drain of the fet. nothing is
> physically
> > >> >> shorted.
> > >> >> > > a
> > >> >> > > > > dead
> > >> >> > > > > > >> fet? any ideas?
> > >> >> > > > > > >> andrew.
> > >> >> > > > > > >>
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >The CGS Modular Synth home page:
> > >> >http://www.cgs.synth.net/
> > >> >> > > > > > >
> > >> >> > > > > > >Yahoo! Groups Links
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > > >
> > >> >> > > > > >
> > >> >> > > > >
> > >__________________________________________________________
> > >> >> > > > > __
> > >> >> > > > > > Ken Stone sasami@
> > >> >> > > > > > Modular Synth PCBs for sale
> > >> >> > > > > <http://www.blaze.net.au/~sasami/synth/>
> > >> >> > > > > > Australian Miniature Horses & Ponies
> > >> >> > > > > <http://www.blaze.net.au/~sasami/>
> > >> >> > > > > >
> > >> >> > > > >
> > >> >> > > > >
> > >> >> > > > >
> > >> >> > > >
> > >> >> > > >
> > >> >> > > >
> > >> >> > > > [Non-text portions of this message have been removed]
> > >> >> > > >
> > >> >> > >
> > >> >> >
> > >> >>
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >> >
> > >> >Yahoo! Groups Links
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >>
> > >__________________________________________________________
> > >__
> > >> Ken Stone sasami@
> > >> Modular Synth PCBs for sale
> > ><http://www.blaze.net.au/~sasami/synth/>
> > >> Australian Miniature Horses & Ponies
> > ><http://www.blaze.net.au/~sasami/>
> > >>
> > >
> > >
> > >
> > >
> > >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > __________________________________________________________
> > Ken Stone sasami@...
> > Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> > Australian Miniature Horses & Ponies
> <http://www.blaze.net.au/~sasami/>
> >
>
>
>

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