Hi Doug,
thanks for your thoughts.
thanks for your thoughts.
--- In cgs_synth@yahoogroups.com, "Doug" <cgsyahoo@...> wrote:
> Glad you got #2 working. When you say "removing other PCBs downstream", that could indicate bad grounding practices or a multitude of other issues. Can you elaborate a bit?
I had the output of the processor section of the board connected to a DC Mixer board for offset, and then running to the Analog Logic board. They were all part of the same module (i.e. behind same panel) but at some point in the process I gave them all separate power lines. I'll deal with those guys later though...
I've got everything working on the problem VCS board except the Trigger In and End Out, so it can't cycle. All other inputs and the Output work fine, as does the LED now.
I get a faint flicker on the LED from an external trigger, but no noticeable output voltage from the Output. Using a patch cable to connect End Out to Trigger in gives no response at all.
> I'm not familiar with this particular board but it might be helpful to see clear photos of the board, it's neighbors and the wiring around the area.
I can try to get this later on. I made some voltage comparisons between the IC pins of the working and not-working PCBs a while ago, would something like that be useful?
> Did you use IC sockets? I might try replacing that 3900 with a different one (again).
All ICs replaced at least once. Also most of the transistors, espc the one in the End/Trigger section.
One thing I've noticed is that with these boards, it's *very* easy to lift the traces. Other CGS boards haven't given me this much trouble. Ken, is your new PCB company able to do the same thickness of traces as before?
> How good are your soldering skills? Are you comfortable that you can spot a tiny short or bad solder joint. Sorry if that's blunt, but it gives everyone a better idea of your confidence level.
Normally, they are excellent. I've successfully built something like 16 modules from PCBs already, and a handful more on protoboard. Plus I was trained as a silversmith some years ago ;-)
Best!
D.
> Keep the questions rolling. We're bound to figure it out :-)
>
> Regards,
>
> Doug
>
> --- In cgs_synth@yahoogroups.com, "derekatumaticdotnl" <derek@> wrote:
> >
> > Second problem of the wobbling voltage fixed by removing some other PCBs further downstream (DC Mixers + Analog Voltage, will be debuggered later), so that VCS works fine. The first one is still kaput however. Suggestions welcome!
> >
> > D.
> >
> > --- In cgs_synth@yahoogroups.com, "derekatumaticdotnl" <derek@> wrote:
> >
> > > The other VCS is even more confusing than the first. Again, input, pots and CV all seem to work, trigger and end out definitely do not. This time, the LED works, but the whole thing seems more like a Source of Uncertainty module! The voltage wobbles all over the place, and seems to be affected by my body resistance/capacitance!
> >
>