Hi Teis (and apologize me for my engRish
),
For me there's no problem to read/write in english, but I don't know what the forum's administrators think about having posts written in other languages than italian. However now I answer to your post, but eventually think about contacting me in PM, so we can continue this discussion without disturbing the public forum.
Unfortunately I haven't the circuit schematics nor any documentation about this instrument, I tried to search on the Internet for more documents but I found absolutely nothing. So for the repairs I done until this moment (and it's not finished yet) I had to rely on intuition, following the circuits and measuring with an oscilloscope.
Remember that I'm not an electronic engineer/technician and I'm repairing this instrument with the help of a friend which is electronic engineer, so what I'll say may contain some inaccuracies.
For what I could see the percussion/sustain section it's handled by one of the 2 vertically mounted boards, more precisely by the most inner one, closest to the 12 oscillator boards. I suggest to begin to replace all the caps/resistors on the about 55 - 60 tiny boards which are soldered on the longer one, this should be enough to restore the percussion/sustain section. Replace them with components of the same values. Personally I had to replace all the blue caps on these tiny boards because the sustain wasn't the same on all keys. If I remember correctly these are 6,5 uF caps.
The 2nd of these 2 boards handles the filters/registers stuff and possibly other things that I'm not aware of.
Regarding the other defect (the volume drop when chords are played) may be that some preamp stage it's in trouble, but I still don't know where this is located, maybe near the power supply as the output jack resides there.
In
this thread there are some photos of the restoring process of my organ, which by the way stopped for a lot of time and I'll have to restart in the next months, as my friend lately was very busy.
I hope this could at least give some help.
Edited 30 Set. 2011 10:43