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Cgs synth

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Re: Debugging Gate Sequencer

2007-07-29 by sasami@hotkey.net.au

There is also a 100n cap between pins 1 and 3 of the op-amp, apparently to
speed up the transition. Try removing it. It isn't on the schematics.
Me thinks it's time this went to version 2.

Ken


>Alright I figured out my Hold problem, defective toggle (my first one haha)...
>
>As for the Reset, no luck.... Parts are correct, I tried replaced the 100K
with a 330K like you suggested and nothing....
>
>This is a V1.4 board, on the schem (earlier version) after the 15K there is
a diode, 100k res, 100n cap marked *not present on earlier PCB. It does not
appear to be on this version, only other difference I see is at the reset
input pad there is a diode going to +15V....
>
>Also I am not using the Disable Jack and have installed the diode afer its
pad on the pcb....
>
>hmmmmm
>
>
> ----- Original Message -----
> From: sasami@...
> To: cgs_synth@yahoogroups.com
> Sent: Friday, July 27, 2007 10:21 PM
> Subject: Re: [cgs_synth] Debugging Gate Sequencer
>
>
> First, I suggest that you have a parts installation error around the reset
> input. Failing that:-
>
> >My reset jack will reset with a gate of approx 10V, the 5V gate outs of say
> my Sequential Swicth will not reset the module.
>
> It should be sensitive to around 2 volts. Try increasing the value of the
> 100k from pin 3 to earth to 330k.
>
> >In Hold mode it is not working correctly, with a sequence of 8 steps when I
> change it to Hold mode it will just loop between 2-8, and as I change
> sequence length it will loop between smaller amounts... Every now and than
> when I change the sequence length it will work correctly for a second.
>
> behavior wne actually rotating the switch can be eratic.
>
> >I am using a LM358 on the main board, I tried a few TL072cp and I cannot
> get the 4017 to clock at all with the TL072.
>
> Try different LM358 or other op-amps. If you can only get TL072, disconnect
> its pin 4 and connect it to -VE instead of 0V AND add a diode between pin 7
> of the TL072 and pin 14 of the 4017, cutting the track (i.e. put the diode
> in series, cathode towards the 4017). Add a 100k from pin 14 of the 4017 to
> 0 volts.
>
> >I've swapped out the 4017 for another althou all I have on hand is CD4017BE.
>
> Nothing wrong with those 4017.
>
> Ken
> __________________________________________________________
> Ken Stone sasami@...
> 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/
>
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>
>
_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

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