[sdiy] little BIG help on KORG DELTA

Antonio Tuzzi antoniotuzzi at gmail.com
Tue Jun 28 11:14:28 CEST 2011


Hello friends,

I have korg delta that is giving me headache...


the string parts works correctly
but the synth part is buggy in the filter area:


http://img692.imageshack.us/img692/196/deltasynthpcb.png

in this schema you get some info on what is working:

Audio signal is present at point  1
if I connect to point 2 (out of the filter) directlyI'm getting the signal in final VCA

if the filter is in BP mode (point 1, down) the signal leaks in the Resonance pot (point 4), when is high and I can hear in the final VCA

the SA798 is working and I changed it too (point 3)
if I detach (desolder) the point 3, still the signal is missing

I changed 2 sets of LM13600 (I have sockets )
and I changed the caps of the filters (c21 22 23 24)

(the ic9 is changed too, but in any case is involved only when in BP mode)

I really don't know the audio is completely lost in there...


If you have any suggestion on how to continue debugging... 

thank you
antonio






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