I'm in a process of giving this Classic away next week, so took it under inspection once again. Told this had an sadmac -problem but wanted to be sure.

I thought i had removed the RAM expansion board before, but seems that i had not. So, after removing the RAM expansion board, it booted just fine, just not to 7.1 due lack of memory. So... i tested few more RAM boards and RAM modules, even the one i got sealed in a bag-board (brand new) with and without RAM, still the sadmac on boot. So it's an motherboard issue but this can still be used with System 6 for time being if nothing else. So istalled fresh System 6.0.5 Finnish to it.

At least it's alive!