[sdiy] Pin 14 on the 3340

[Oakley Sound]

RS > Maybe the capacitor at pin 9 (soft sync) to GND is broken...

Unfortunately not. I've got several voice cards that show the same 
problem and some of them have new components. I have found out a little 
more. The instability does still occur in positions nearer the power 
supply, however, it is less obvious. Some specimens of AS3340 do not 
exhibit the problem. It only happens when the pulse width is less than 
50% increasing at the positive excursion becomes thinner.

Adding 100nF to each of the +15V and -5V pins does decrease it but not 
get rid of it. Removing the pin 14 decoupling capacitor seems to help. 
But adding thicker 0V connections to the board and to the offending VCO 
does not help. Both VCO1 and VCO2 have the same problem. Using a new 
issue rev G CEM3340, or original CEM3340, does not exhibit the problem 
at all.

Time to buy ten more rev G CEM3340s I think.

Tony

www.oakleysound.com