Thanks everyone for support.

Wally your Se30 knowledge is amazing!

I've checked all capacitors four times: their bypass grounding seems fine.

Moreover i checked and rechecked those lines whose rework wasn't properly clean:

J12-6 -C8+ ground line is fine

J12-7 -C9+ ground line is fine

UB10-15/UB11-15 +C5- ground line is fine

UB11-10 +C4- ground line is fine

UB11-7 +C6- ground line is fine

Furthermore i checked with naked eye C1, C10, C12, C13, C7: their soldering was clean and troubleless. When i have some time i'll check better with a lens those areas inheriting audio and main connector.

Tomorrow i'll test resistance reading between voltage pins and ground and if necessary i'll check for shorted caps. I work as MD and this stubborn behaviour remembers me a sort of terminal patient overtreatment. :-(

I recapped succesfully 1 macintosh II, two nubus video boards: this was the first time i've met aluminum SMD capacitors with spot glued base. Moreover they seem more prone to leak than standard aluminum axial like those used on non SMD era. Anyway ...i'll let you know

Thanks

Greetings.