The assembly in general has been going well, no screw-ups about placing
the wrong components or messing up the orientation. I've even
gone over the part list for each section twice now, carefully checking
that what was in my board was correct. The VCO works fine and the
VCF works.. but rather poorly. It seems that even with the cutoff
all the way up the signal is being filtered, and the cutoff doesn't
track along with the VCO, even so I can't create a note that's low
enough to see a clean saw or square. Turning the env amount knob
up causes the cutoff to drop, perhaps this is normal?. Again,
I've checked *very carefully* *twice* *each* component and it's
orientation using a magnifying glass and a bright halogen lamp.
They are all correct, each resistor, capacitor and transistor, and they
were all correct the first time I soldered them in. Now,
leaving the VCF behind the envelope appears to be working as
proper. Measurements at D35 and 36 agree with what is listed in
the fab manual and the VCF will respond to triggering the envelope, but
I'm doubtful that the decay is working as it's quite snappy at either
end of it's range. Still, I pressed on and assembled the VCA and
here is where things get discouraging. No signal at all while
performing the test from the manual. In fact I don't understand
why I would be using R10 to generate a pulse when before I was using R3
(using R3/R146 the VCF will respond). Measuring R10 certainly
didn't show 10V, and it was part of the pre-assembled USB section, so
I'm wondering if this is an error in the manual. Now, I would
like to know if I can test the difference between the VCA being
triggered and the VCA working. In fact the signal from the VCF
disappears after C21 and R121, after that all I can read is 5V, almost
everywhere in the VCA circuit. I need some advice on this.
I don't understand how the filter works well enough to break it into an
input stage/ output stage and definitely don't know what I would want
to see anyway and the VCA has me completely lost due the the mystifying
BA6110 in 9 pin SIP for which I can't find a datasheet.<br>