Ack! Virtual ground! Have I forgotten everything?
I'd already gotten my answer earlier, though, as the B channel works
well now. The A channel isn't so cooperative. There's nothing past
the second opamp stage. The diode tested okay and there's a feeble
(just over the noise) signal present at the 4011 pins 1 and 2, but
the output is simply high at pin three. Voltages are good at all
the devices, diodes are oriented correctly...I gotta figure this
out. At first, I figured the 4011 was just dead, but no such luck.
I've got a pot for the x2 output of both A and B. If I turn the pot
full counter-clockwise, the B channel drops out. It would seem I
need extra resistance above ground on those pots. Everything else
on the B channel is fine - actually an excellent sound! I can't
wait to get both channels working, this is a very versatile module.
Any ideas will be considered!
Chub
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--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>
> >If I use switches instead of pots for the divider outputs, will I
need
> >to add a 47K resistor to ground for each output to the mixer?
I've
> >finished this pcb but have no output except the channel B x2.
This is
> >sent straight to a pot and the mixer.
>
> No need to add anything to ground. Reason 1 - it doesn't require a
load.
> Reason 2 - it's getting one anyway when it connects to the summing
node of
> the mixer (Virtual ground).
>
> Ken
>
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