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.
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/>
>
