Okay, so it's probably not those. I'm quite certain the speed & shape pots are wired correctly.
But I'm wondering, which part of the PCB is LFO1 and which is LFO2 ? Not sure if that matters, but it's most likely that I've done the swap/join switches not correctly. I've hooked up the top LFO's VARI pot pads ("top" when Power pads are at the bottom) to the swap switch, and so on... Dunno if this could influence the oscillation ?
Also removed the bottom's 074, and indeed then the lower LFO has no more output.
Top LFO outputs still remain at -3V and -8V; and still no LEDs.
What else can I look for ?
Or should I try to skip the switches as a test, and hook up the outputs & pots directly ?
_g
But I'm wondering, which part of the PCB is LFO1 and which is LFO2 ? Not sure if that matters, but it's most likely that I've done the swap/join switches not correctly. I've hooked up the top LFO's VARI pot pads ("top" when Power pads are at the bottom) to the swap switch, and so on... Dunno if this could influence the oscillation ?
Also removed the bottom's 074, and indeed then the lower LFO has no more output.
Top LFO outputs still remain at -3V and -8V; and still no LEDs.
What else can I look for ?
Or should I try to skip the switches as a test, and hook up the outputs & pots directly ?
_g
--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>
> The first step would to be to find out why it is not oscillating, so
> investigate the circuit around that area - and that means the speed pot and
> the shape pot. Getting two wires to a pot swapped could well kill it.
>
> Ken
>
> >...more specifically the Utility LFO, to start with.
> >
> >Wired it up, with Join/Swap switches. +/-12V feed, banana jacks.
> >LEDs don't flash, but a quick DVM measuring at the outputs gives me app.
> -4V on most and even -8V on some other outputs (the Vari's, I think). The
> output voltages don't seem to fluctuate at all... (I did not do an audio
> check, nor do I have a scope)
> >
> >Apart from the obvious basic legwork (IC's put in correctly, no bad solder
> joints, no short circuits at first sight, and that tricky little jumper is
> present), what would be the methodology to start hunting for bugs ? Which
> points should/could I measure first ? What would be good deductive steps to
> undertake to pinpoint the problem ?
> >
> >
> >tia !
> >
> >_guy
> >
> >
> >
> >
> >------------------------------------
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >Yahoo! Groups Links
> >
> >
> >
> >
> _______________________________________________________________________
> Ken Stone sasami@... otherunicorn@...
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>