-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
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]
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 KenExactly an octave when CV removed.
>
>I've moved on to the SPAN trimmer.
>
>One of the VCO's is adjusting fine with 1V input on the 1V/Oct input.
>one semitone short of a full octave ; no matter what i do with the SPAN trimmer.
>Under the same input conditions , the second VCO is not adjusting beyond
>the knobs in to adjust the ZERO 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
>calibration process ?
>I have the 'Tune' knob at 12 o'clock.
>
>Does the position of the 'Frequency' Knob have any bearing on the
>__________________________________________________________
>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]