Cgs synth

I get 0.6V to 14V range at pin 10. Trimmer wiper is sitting at 11.57V.

Ken

>Hi Ken
>
>When reading (L pin 10 LM3900) with DMM ; it swings from fully CCW +2.54 to

fully CW+2.07V.

>
>no jump or difference in voltage around 1pm mark at all.
>
>Should i check 'S' and 'R' ?
>
>
>________________________________
> From: "sasami@..." <sasami@...>
>To: cgs_synth@yahoogroups.com
>Sent: Sunday, December 9, 2012 3:32 PM
>Subject: Re: [cgs_synth] CGS77 - Serge VCF
>
>
>Â
>
>>Do you think it could be a problem with transistors here ?
>
>I doubt it. I've built them with generic parts.
>
>I can only imagine you have a wrong value part. Make sure the CV MIXER is
>working. Forget about listening to it. Find out what voltages are doing at
>point "L". It should be giving smooth responces to pot rotation. If it stays
>at a fixed voltage until 1'oclock on the pot, then something is wrong with
>that mixer stage.
>
>Once you work that out, the next step should be more obvious.
>
>Ken
>
>>
>>
>>________________________________
>> From: "sasami@..." <sasami@...>
>>To: cgs_synth@yahoogroups.com
>>Sent: Thursday, December 6, 2012 11:14 AM
>>Subject: Re: [cgs_synth] CGS77 - Serge VCF
>>
>>
>>ÂÂ
>>Are you not able to compensate for this using the trimmer? Also make sure
>>your FREQ CV pot input is set to the center of its travel when you do the

test.

>>I really don't know why this is happening. I can only guess, but it seems
>>that the CV mixer output voltage is too low - too "negative", requiring you
>>to turn the pot that far around before you reach the point where the expo
>>converters can respond. Is it the double sided or single sided version?
>>Ken
>>
>>>CW is wired to 0V
>>>
>>>
>>>________________________________
>>> From: "sasami@..." <sasami@...>
>>>To: cgs_synth@yahoogroups.com
>>>Sent: Thursday, December 6, 2012 10:13 AM
>>>Subject: Re: [cgs_synth] CGS77 - Serge VCF
>>>
>>>
>>>ÂÂÂ
>>>Have you wired the CW terminal of the pot to -VE or 0V?
>>>Ken
>>>
>>>>Hi Ken
>>>>
>>>>I am just troubleshooting the BOG panel and am having problems with the
>>>Serge VCF.
>>>>
>>>>When i move the Freq Pot the filter does not kick in until about the
>>>'1o'clock' point on the pot's travel.
>>>>
>>>>Below that point , nothing.
>>>>
>>>>Everything else seems to be working , all ins and outs doing what they
>should.
>>>>
>>>>I have swapped the LM3900 and this has had no effect.
>>>>
>>>>[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]
>>>
>>>
>>>
>>>------------------------------------
>>>
>>>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]
>>
>>
>>
>>------------------------------------
>>
>>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]
>
>
>
>------------------------------------
>
>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/>