[sdiy] Crap.. I need help with my x0x

[Seb Francis]

If you want a copy of BA6110.pdf datasheet, email me (offlist)

Jeff Farr wrote:

> 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.