Cgs synth

>...more specifically the Utility LFO, to start with.
>
>Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
>LEDs don't flash, but a quick DVM measuring at the outputs gives me app.

>
>Apart from the obvious basic legwork (IC's put in correctly, no bad solder

>
>
>tia !
>
>_guy
>
>
>
>
>------------------------------------
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>Yahoo! Groups Links
>
>
>
>

--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>
> The first step would to be to find out why it is not oscillating, so
> investigate the circuit around that area - and that means the speed pot and
> the shape pot. Getting two wires to a pot swapped could well kill it.
>
> Ken
>
> >...more specifically the Utility LFO, to start with.
> >
> >Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
> >LEDs don't flash, but a quick DVM measuring at the outputs gives me app.
> -4V on most and even -8V on some other outputs (the Vari's, I think). The
> output voltages don't seem to fluctuate at all... (I did not do an audio
> check, nor do I have a scope)
> >
> >Apart from the obvious basic legwork (IC's put in correctly, no bad solder
> joints, no short circuits at first sight, and that tricky little jumper is
> present), what would be the methodology to start hunting for bugs ? Which
> points should/could I measure first ? What would be good deductive steps to
> undertake to pinpoint the problem ?
> >
> >
> >tia !
> >
> >_guy
> >
> >
> >
> >
> >------------------------------------
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >Yahoo! Groups Links
> >
> >
> >
> >
> _______________________________________________________________________
> Ken Stone sasami@... otherunicorn@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>

>
> >Okay, so it's probably not those. I'm quite certain the speed & shape pots
> are wired correctly.
>
> Something is preventing them from oscillating. Whatever it is, that is what
> you need to find. Make sure your 1N4148 diodes are in the right direction.
> Also make sure that both power rails are getting to the chips.

>
> >But I'm wondering, which part of the PCB is LFO1 and which is LFO2 ? Not
> sure if that matters, but it's most likely that I've done the swap/join
> switches not correctly. I've hooked up the top LFO's VARI pot pads ("top"
> when Power pads are at the bottom) to the swap switch, and so on... Dunno if
> this could influence the oscillation ?
>
> Either can be LFO1 - depends on how you wire them. Usually I would consider
> the one nearer the power connector to be LFO 1

>
> >Or should I try to skip the switches as a test, and hook up the outputs &
> pots directly ?
>
> The switches and vari pots are the last of your worries - they don't affect
> the core.

>
> >
> >_g
> >
> >
> >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> >>
> >> The first step would to be to find out why it is not oscillating, so
> >> investigate the circuit around that area - and that means the speed pot and
> >> the shape pot. Getting two wires to a pot swapped could well kill it.
> >>
> >> Ken
> >>
> >> >...more specifically the Utility LFO, to start with.
> >> >
> >> >Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
> >> >LEDs don't flash, but a quick DVM measuring at the outputs gives me app.
> >> -4V on most and even -8V on some other outputs (the Vari's, I think). The
> >> output voltages don't seem to fluctuate at all... (I did not do an audio
> >> check, nor do I have a scope)
> >> >
> >> >Apart from the obvious basic legwork (IC's put in correctly, no bad solder
> >> joints, no short circuits at first sight, and that tricky little jumper is
> >> present), what would be the methodology to start hunting for bugs ? Which
> >> points should/could I measure first ? What would be good deductive steps to
> >> undertake to pinpoint the problem ?
> >> >
> >> >
> >> >tia !
> >> >
> >> >_guy
> >> >
> >> >
> >> >
> >> >
> >> >------------------------------------
> >> >
> >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >> >Yahoo! Groups Links
> >> >
> >> >
> >> >
> >> >
> >> _______________________________________________________________________
> >> Ken Stone sasami@ otherunicorn@
> >> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> >> 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@... otherunicorn@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>

--- In cgs_synth@yahoogroups.com, "Guy" <guy@...> wrote:
>
> --- In cgs_synth@yahoogroups.com, sasami@ wrote:
> >
> > >Okay, so it's probably not those. I'm quite certain the speed & shape pots
> > are wired correctly.
> >
> > Something is preventing them from oscillating. Whatever it is, that is what
> > you need to find. Make sure your 1N4148 diodes are in the right direction.
> > Also make sure that both power rails are getting to the chips.
>
> Ah yes, I should start there. It's outputting only negative voltages, so that makes sense... Lemme look up the 074 datasheet and find out where to measure.
> Diodes are fine.
>
> >
> > >But I'm wondering, which part of the PCB is LFO1 and which is LFO2 ? Not
> > sure if that matters, but it's most likely that I've done the swap/join
> > switches not correctly. I've hooked up the top LFO's VARI pot pads ("top"
> > when Power pads are at the bottom) to the swap switch, and so on... Dunno if
> > this could influence the oscillation ?
> >
> > Either can be LFO1 - depends on how you wire them. Usually I would consider
> > the one nearer the power connector to be LFO 1
>
> Hmm, okay, so that's my LFO 2. :-)
>
> >
> > >Or should I try to skip the switches as a test, and hook up the outputs &
> > pots directly ?
> >
> > The switches and vari pots are the last of your worries - they don't affect
> > the core.
>
> Thanks for telling me now. I was just about to dismantle half of the wiring...
>
> _g
>
>
> >
> > >
> > >_g
> > >
> > >
> > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >>
> > >> The first step would to be to find out why it is not oscillating, so
> > >> investigate the circuit around that area - and that means the speed pot and
> > >> the shape pot. Getting two wires to a pot swapped could well kill it.
> > >>
> > >> Ken
> > >>
> > >> >...more specifically the Utility LFO, to start with.
> > >> >
> > >> >Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
> > >> >LEDs don't flash, but a quick DVM measuring at the outputs gives me app.
> > >> -4V on most and even -8V on some other outputs (the Vari's, I think). The
> > >> output voltages don't seem to fluctuate at all... (I did not do an audio
> > >> check, nor do I have a scope)
> > >> >
> > >> >Apart from the obvious basic legwork (IC's put in correctly, no bad solder
> > >> joints, no short circuits at first sight, and that tricky little jumper is
> > >> present), what would be the methodology to start hunting for bugs ? Which
> > >> points should/could I measure first ? What would be good deductive steps to
> > >> undertake to pinpoint the problem ?
> > >> >
> > >> >
> > >> >tia !
> > >> >
> > >> >_guy
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >------------------------------------
> > >> >
> > >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >> >Yahoo! Groups Links
> > >> >
> > >> >
> > >> >
> > >> >
> > >> _______________________________________________________________________
> > >> Ken Stone sasami@ otherunicorn@
> > >> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> > >> 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@ otherunicorn@
> > Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> > Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
> >
>

--- In cgs_synth@yahoogroups.com, "Guy" <guy@...> wrote:
>
> No +V going to the chips. The +V bead wasn't soldered properly... how dumb.
>
> LFO still isn't working though. Vari & Mix outputs still spitting out a steady negative voltage, but Pulse & Square now going positive (only)...
>
> Hmmm... onwards.
>
> _g
>
>
> --- In cgs_synth@yahoogroups.com, "Guy" <guy@> wrote:
> >
> > --- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >
> > > >Okay, so it's probably not those. I'm quite certain the speed & shape pots
> > > are wired correctly.
> > >
> > > Something is preventing them from oscillating. Whatever it is, that is what
> > > you need to find. Make sure your 1N4148 diodes are in the right direction.
> > > Also make sure that both power rails are getting to the chips.
> >
> > Ah yes, I should start there. It's outputting only negative voltages, so that makes sense... Lemme look up the 074 datasheet and find out where to measure.
> > Diodes are fine.
> >
> > >
> > > >But I'm wondering, which part of the PCB is LFO1 and which is LFO2 ? Not
> > > sure if that matters, but it's most likely that I've done the swap/join
> > > switches not correctly. I've hooked up the top LFO's VARI pot pads ("top"
> > > when Power pads are at the bottom) to the swap switch, and so on... Dunno if
> > > this could influence the oscillation ?
> > >
> > > Either can be LFO1 - depends on how you wire them. Usually I would consider
> > > the one nearer the power connector to be LFO 1
> >
> > Hmm, okay, so that's my LFO 2. :-)
> >
> > >
> > > >Or should I try to skip the switches as a test, and hook up the outputs &
> > > pots directly ?
> > >
> > > The switches and vari pots are the last of your worries - they don't affect
> > > the core.
> >
> > Thanks for telling me now. I was just about to dismantle half of the wiring...
> >
> > _g
> >
> >
> > >
> > > >
> > > >_g
> > > >
> > > >
> > > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > > >>
> > > >> The first step would to be to find out why it is not oscillating, so
> > > >> investigate the circuit around that area - and that means the speed pot and
> > > >> the shape pot. Getting two wires to a pot swapped could well kill it.
> > > >>
> > > >> Ken
> > > >>
> > > >> >...more specifically the Utility LFO, to start with.
> > > >> >
> > > >> >Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
> > > >> >LEDs don't flash, but a quick DVM measuring at the outputs gives me app.
> > > >> -4V on most and even -8V on some other outputs (the Vari's, I think). The
> > > >> output voltages don't seem to fluctuate at all... (I did not do an audio
> > > >> check, nor do I have a scope)
> > > >> >
> > > >> >Apart from the obvious basic legwork (IC's put in correctly, no bad solder
> > > >> joints, no short circuits at first sight, and that tricky little jumper is
> > > >> present), what would be the methodology to start hunting for bugs ? Which
> > > >> points should/could I measure first ? What would be good deductive steps to
> > > >> undertake to pinpoint the problem ?
> > > >> >
> > > >> >
> > > >> >tia !
> > > >> >
> > > >> >_guy
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >------------------------------------
> > > >> >
> > > >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > > >> >Yahoo! Groups Links
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> _______________________________________________________________________
> > > >> Ken Stone sasami@ otherunicorn@
> > > >> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> > > >> 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@ otherunicorn@
> > > Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> > > Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
> > >
> >
>

--- On Fri, 15/1/10, sasami@... <sasami@...> wrote:

From: sasami@... <sasami@...>
Subject: Re: [cgs_synth] How to debug non-working modules...
To: cgs_synth@yahoogroups.com
Received: Friday, 15 January, 2010, 2:35 AM


























>Are all your jacks grounded?



It's hard to ground a banana jack!!



Ken



>

>--- On Sat, 9/1/10, Guy <guy@...> wrote:

>

>From: Guy <guy@...>

>Subject: [cgs_synth] How to debug non-working modules...

>To: cgs_synth@yahoogrou ps.com

>Received: Saturday, 9 January, 2010, 11:08 PM

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>Â

>

>

>

>

>

>

>

>

>

> ...more specifically the Utility LFO, to start with.

>

>

>

>Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.

>

>LEDs don't flash, but a quick DVM measuring at the outputs gives me app.

-4V on most and even -8V on some other outputs (the Vari's, I think). The

output voltages don't seem to fluctuate at all... (I did not do an audio

check, nor do I have a scope)

>

>

>

>Apart from the obvious basic legwork (IC's put in correctly, no bad solder

joints, no short circuits at first sight, and that tricky little jumper is

present), what would be the methodology to start hunting for bugs ? Which

points should/could I measure first ? What would be good deductive steps to

undertake to pinpoint the problem ?

>

>

>

>tia !

>

>

>

>_guy

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

____________ _________ _________ _________ _________ _________ _

______

>See what's on at the movies in your area. Find out now:

http://au.movies yahoo.com/ session-times/

>

>[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@hotkey. net.au otherunicorn@ virginbroadband. com.au

Modular Synth PCBs for sale <http://www.cgs synth.net/>

Australian Miniature Horses & Ponies <http://www.blaze net.au/~sasami/>


























__________________________________________________________________________________
See what's on at the movies in your area. Find out now: http://au.movies.yahoo.com/session-times/

[Non-text portions of this message have been removed]