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CGS48 VCO Calibration

CGS48 VCO Calibration

2012-05-26 by Stephen Richards

Hi Ken

I'm calibrating some CGS48 VCO's and i need to know what position to have the knobs in to adjust the ZERO trimmer.

I have the 'Tune' knob at 12 o'clock.

Does the position of the 'Frequency' Knob have any bearing on the calibration process ?

Should it be at 12 o'clock too ?

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

Re: CGS48 VCO Calibration

2012-05-26 by sasami@hotkey.net.au

>I'm calibrating some CGS48 VCO's and i need to know what position to have
the knobs in to adjust the ZERO trimmer.
>
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
calibration process ?

Yes. Set it to the center position as well. It is one of the pots I am
referring to when I say "the tune controls". I guess I could make that clearer.

Ken

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

Re: CGS48 VCO Calibration

2012-05-26 by Stephen Richards

Great , thanks Ken.


________________________________
Show quoted textHide quoted text
From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Saturday, May 26, 2012 11:57 AM
Subject: Re: [cgs_synth] CGS48 VCO Calibration



>I'm calibrating some CGS48 VCO's and i need to know what position to have
the knobs in to adjust the ZERO trimmer.
>
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
calibration process ?

Yes. Set it to the center position as well. It is one of the pots I am
referring to when I say "the tune controls". I guess I could make that clearer.

Ken

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




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

Re: CGS48 VCO Calibration

2012-05-26 by Stephen Richards

Hi Ken

I've moved on to the SPAN trimmer.

One of the VCO's is adjusting fine with 1V input on the 1V/Oct input. Exactly an octave when CV removed.

Under the same input conditions , the second VCO is not adjusting beyond one semitone short of a full octave ; no matter what i do with the SPAN trimmer.

Any advice on where to troubleshoot this one ?

________________________________
Show quoted textHide quoted text
From: Stephen Richards <okayjustalittle@...>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Saturday, May 26, 2012 11:47 AM
Subject: [cgs_synth] CGS48 VCO Calibration



Hi Ken

I'm calibrating some CGS48 VCO's and i need to know what position to have the knobs in to adjust the ZERO trimmer.

I have the 'Tune' knob at 12 o'clock.

Does the position of the 'Frequency' Knob have any bearing on the calibration process ?

Should it be at 12 o'clock too ?

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




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

Re: CGS48 VCO Calibration

2012-05-26 by sasami@hotkey.net.au

Compare voltages with the one that is working to find out where the problem
is. Check that the op-amps are getting power to both of their power pins.
If the voltages at pin 7 of IC1 can be adjuststed to be more-or less the
same between the working and non-working (irrrespective of what the
frequency is), the fault will be in the exp. converter or the core. The
point here being to prove if the mixer section is working correctly, or if
it has an unexplained offset that is causing it to clip.

Ken
Show quoted textHide quoted text
>Hi Ken
>
>I've moved on to the SPAN trimmer.
>
>One of the VCO's is adjusting fine with 1V input on the 1V/Oct input.
Exactly an octave when CV removed.
>
>Under the same input conditions , the second VCO is not adjusting beyond
one semitone short of a full octave ; no matter what i do with the SPAN trimmer.
>
>Any advice on where to troubleshoot this one ?
>
>________________________________
> From: Stephen Richards <okayjustalittle@...>
>To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
>Sent: Saturday, May 26, 2012 11:47 AM
>Subject: [cgs_synth] CGS48 VCO Calibration
>
>
>Â
>Hi Ken
>
>I'm calibrating some CGS48 VCO's and i need to know what position to have
the knobs in to adjust the ZERO trimmer.
>
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
calibration process ?
>
>Should it be at 12 o'clock too ?
>
>[Non-text portions of this message have been removed]
>
>
>
>
>[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@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: CGS48 VCO Calibration

2012-05-26 by Stephen Richards

-14.91 on pin 4 , 8.38 on pin 7 on IC1 (TL072)

i had no trouble getting both VCO's to 0V on IC1 pin 7 when doing the ZERO trimming.

what is next ?


________________________________
Show quoted textHide quoted text
From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Saturday, May 26, 2012 1:24 PM
Subject: Re: [cgs_synth] CGS48 VCO Calibration



Compare voltages with the one that is working to find out where the problem
is. Check that the op-amps are getting power to both of their power pins.
If the voltages at pin 7 of IC1 can be adjuststed to be more-or less the
same between the working and non-working (irrrespective of what the
frequency is), the fault will be in the exp. converter or the core. The
point here being to prove if the mixer section is working correctly, or if
it has an unexplained offset that is causing it to clip.

Ken

>Hi Ken
>
>I've moved on to the SPAN trimmer.
>
>One of the VCO's is adjusting fine with 1V input on the 1V/Oct input.
Exactly an octave when CV removed.
>
>Under the same input conditions , the second VCO is not adjusting beyond
one semitone short of a full octave ; no matter what i do with the SPAN trimmer.
>
>Any advice on where to troubleshoot this one ?
>
>________________________________
> From: Stephen Richards <okayjustalittle@...>
>To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
>Sent: Saturday, May 26, 2012 11:47 AM
>Subject: [cgs_synth] CGS48 VCO Calibration
>
>
>Â
>Hi Ken
>
>I'm calibrating some CGS48 VCO's and i need to know what position to have
the knobs in to adjust the ZERO trimmer.
>
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
calibration process ?
>
>Should it be at 12 o'clock too ?
>
>[Non-text portions of this message have been removed]
>
>
>
>
>[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@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>




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

Re: CGS48 VCO Calibration

2012-05-26 by Stephen Richards

I've sorted it. I was using a 9V battery with a 100K resistor for my voltage source.

I checked some old EM postings and found what i was doing wrong.

Was taking DMM readings from the pot legs not the 1V/Oct input jack so i got voltage drop.

All seems good now.

Live and learn...


________________________________
Show quoted textHide quoted text
From: Stephen Richards <okayjustalittle@...>
To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
Sent: Saturday, May 26, 2012 2:12 PM
Subject: Re: [cgs_synth] CGS48 VCO Calibration



-14.91 on pin 4 , 8.38 on pin 7 on IC1 (TL072)

i had no trouble getting both VCO's to 0V on IC1 pin 7 when doing the ZERO trimming.

what is next ?

________________________________
From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Saturday, May 26, 2012 1:24 PM
Subject: Re: [cgs_synth] CGS48 VCO Calibration



Compare voltages with the one that is working to find out where the problem
is. Check that the op-amps are getting power to both of their power pins.
If the voltages at pin 7 of IC1 can be adjuststed to be more-or less the
same between the working and non-working (irrrespective of what the
frequency is), the fault will be in the exp. converter or the core. The
point here being to prove if the mixer section is working correctly, or if
it has an unexplained offset that is causing it to clip.

Ken

>Hi Ken
>
>I've moved on to the SPAN trimmer.
>
>One of the VCO's is adjusting fine with 1V input on the 1V/Oct input.
Exactly an octave when CV removed.
>
>Under the same input conditions , the second VCO is not adjusting beyond
one semitone short of a full octave ; no matter what i do with the SPAN trimmer.
>
>Any advice on where to troubleshoot this one ?
>
>________________________________
> From: Stephen Richards <okayjustalittle@...>
>To: "cgs_synth@yahoogroups.com" <cgs_synth@yahoogroups.com>
>Sent: Saturday, May 26, 2012 11:47 AM
>Subject: [cgs_synth] CGS48 VCO Calibration
>
>
>Â
>Hi Ken
>
>I'm calibrating some CGS48 VCO's and i need to know what position to have
the knobs in to adjust the ZERO trimmer.
>
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
calibration process ?
>
>Should it be at 12 o'clock too ?
>
>[Non-text portions of this message have been removed]
>
>
>
>
>[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@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

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




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

Re: CGS48 VCO Calibration

2012-05-26 by sasami@hotkey.net.au

>I've sorted it. I was using a 9V battery with a 100K resistor for my
voltage source.Â
>
>I checked some old EM postings and found what i was doing wrong.
>
>Was taking DMM readings from the pot legs not the 1V/Oct input jack so i
got voltage drop.
>
>All seems good now.
>
>Live and learn...
>

Cool. Glad you could sort it out.

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

Re: CGS48 VCO Calibration

2012-05-26 by Richarius Molindarius

Lately, when I've been recalibrating my Ken Stone; Ian Fritz; Thomas Henry
and Ray Wilson VCOs, I've been disconnecting all 'CV input' (including the
previous Coarse and Fine pots), to tune the VCOs to 1V/oct. from an
otherwise 'Ground' reference. (To set my initial frequency at 40hz.)

That's been working beautifully for me. :)

I've also been 0.01%'ing my 100k 1% CV input resistors (and I forget the
value for Fine tuning. 3m3 I think.) to make sure my inputs from everywhere
are as tight as possible.

Same thing with my Octave and Semitone rotary switches that I built in
February. 0.01%'ing their 10k 1% resistors.


--
Take care,
Warmth and Peace,
Rich

http://www.damian.deathlehem.com/ - my modular synth
http://deathlehem.com/php/ - The S0und 0f L0g1c - Lunetta / noise Forum
(email for authorization confirmation.)
http://www.youtube.com/dolphinicus/ - various module videos of mine / etc.


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

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