From: "
sasami@..." <
sasami@...>
To:
cgs_synth@yahoogroups.com
Sent: Sunday, December 9, 2012 3:32 PM
Subject: Re: [cgs_synth] CGS77 - Serge VCF
>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
>
>
>Â
>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
>>
>>
>>ÂÂ
>>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]