Cgs synth

Any DC present in the circuit at that point would be inherent in the design.
It's just not caused problems before. There isn't a "leak" as such to be
tracked down. For the purposes of test, lift the wire from the pot itself,
and add the capacitor there. Don't modify the PCB.

Ken

>
>
>thanks. when i get a chance i will look in to this.
>
>is it possible that the dc leak is coming from the power supply? im
>using the cgs14 built to spec with positive measuring 14.8-14.95 and
>negative sitting happily on 15v. i am thinking one of my filter caps
>or possibly the positive regulator isnt working right. i am thinking
>that a low battery in my multimeter could also be contributing to this
> reading on the positive voltage.
>
>if its not the psu where would u trace back the dc to? i will try
>installing that cap but i would rather keep it clean and to the boards
>spec.
>
>--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>> The +6V is only there as part of a bus system I was using in some of my
>> panels that did require +6V - old Serge stuff mostly. 6 volts is not
>used in
>> any CGS board.
>>
>> One known cause of scratchiness showing with pots is if there is a
>DC signal
>> involved. I don't know if the following will help or be a total
>failure, but
>> try placing a 10uF electro in series with the pot to block any DC
>component.
>> Before you do though, us a multimeter to work out which end is more
>positive
>> so you get the cap in the right way around.
>>
>> Ken
>>
>>
>> >
>> >
>> >ok so i went out and bought a new pot just to drop in in case the pot
>> >i had was bad. seemed it was. i dropped it in and still its scratchy.
>> >is it possible that i am wiring the legs of the pot up wrong? whilst
>> >trawling the message archives i noted that ken advises that the third
>> >leg of the pot is not connected hence i havent grounded it.
>> >
>> >i was about to try peng's suggestions but then i realised i have
>> >nothing connected to the +6v pad.
>> >
>> >i run the ground to the frequency pot then run the ground across to
>> >some perfboard where ive tied in the grounds of the input output and
>> >volume pot. the 6v connector isnt used at all!
>> >
>> >--- In cgs_synth@yahoogroups.com, "peng3002" <peng3002@y...> wrote:
>> >>
>> >> Hold up before replacing the pot. I had a similar problem ith the
>Res
>> >> pot. It actually came from other pots/jacks not being grounded. Next
>> >> to the power supply header there is a "6V" hole on the pcb. Make
>sure
>> >> if your using this hole to run a ground line to pots/jacks to solder
>> >> a link to the ground trace right next to it. Cleared up my crackle
>> >> problems, maybe it'll work for you.
>> >>
>> >> As far as output levels go...I took out the link and replaced it
>with
>> >> a 390K resistor.
>> >>
>> >> As a side note: I think Ken says to breadboard first. This is great
>> >> advice. For instance: I built the pulse divider and it works
>> >> perfectly, but it puts out 13-15volts and I would have preferred
>> >> 5volts. It's simply a matter of changing some resistors to get the
>> >> output level I want, but after everything is wired solder work
>can be
>> >> a little awkward.
>> >>
>> >> Phil
>> >>
>> >>
>> >> --- In cgs_synth@yahoogroups.com, "hiriseau" <sean@p...> wrote:
>> >> >
>> >> > thanks i will get another one pronto, its a sealed pot so nothing i
>> >> > can really do about it. and its only a couple of dollars to get a
>> >> new
>> >> > one.
>> >> >
>> >> > with the level, considering that i will be using the filter in a
>> >> tweak
>> >> > hard on the fly sort of role, would i be better off using the trim
>> >> pot
>> >> > to set the output level and then attenuator on the input, so that i
>> >> > don't kill any club sound systems and peoples ears?
>> >> >
>> >> > --- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>> >> > > >the resonance pot is EXTREMELY crackly whenever i move it.
>> >> > >
>> >> > > That's a dud pot. It isn't a solder issue, but rather dust or
>> >> > "corrosion" on
>> >> > > the pot resistive strip. A shot of electrolube contact
>cleaner may
>> >> > help. A
>> >> > > better pot is the best solution.
>> >> > >
>> >> > > >secondly, levels. i have the link in and i have a 50k log
>pot in
>> >> (the
>> >> > > >same 9mm alpha) and it doesnt seem to be working too well.
>it is
>> >> low
>> >> > > >in volume then BANG heaps of volume. my suspicion is that i
>> >> should be
>> >> > > >using a linear pot instead of a log pot. this is what it sounds
>> >> like
>> >> > > >http://users.bigpond.net.au/xpander/level.mp3 would i be better
>> >> off
>> >> > > >using the pot as an attenuator on the input stage, and using a
>> >> trim
>> >> > > >pot on the level to tweak it to where i want?
>> >> > >
>> >> > > Yes, a linear pot would probably be better. In fact, I rarely use
>> >> > log pots
>> >> > > in synthesizers at all.
>> >> > >
>> >> > > Ken
>> >> > >
>> >> > >
>> >>
>______________________________________________________________________
>> >> _
>> >> > > Ken Stone sasami@h... or sasami@c...
>> >> > > Modular Synth PCBs for sale
>> >> <http://www.blaze.net.au/~sasami/synth/>
>> >> > > Australian Miniature Horses & Ponies
>> >> <http://www.blaze.net.au/~sasami/>
>> >
>> >
>> >
>> >
>> >
>> >
>> >See the following URLS for the CGS Modular Synth home page:
>> >Main: http://www.cgs.synth.net/
>> >Secondary: http://otherunicorn.0catch.com/synth/
>> >Yahoo! Groups Links
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> _______________________________________________________________________
>> Ken Stone sasami@h... or sasami@c...
>> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
>> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>
>
>
>
>
>
>See the following URLS for the CGS Modular Synth home page:
>Main: http://www.cgs.synth.net/
>Secondary: http://otherunicorn.0catch.com/synth/
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

_______________________________________________________________________
Ken Stone sasami@... or sasami@...
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>