Mac Classic II ROM chip testing

[Dinotech]

Some years ago (~10) my Macintosh Classic II working Ok, but now when power on - "standart" chekboard, no surprises.
Computer board now is recaped, but is still checkboard on screen.
When in my Classic connecting logic board from other Mac Classic - all fine, boot up and working.
All voltages be Ok, so, i don't understand what happened and where is problem. My only idea is that it should check RAM and ROM chips, but I don't know what they are and why I can't read them with programmator.

 

[oldpcguy]

IME the ROM chips are fairly reliable and are unlikely to be the issue. If you've already recapped the board I would then focus on the RAM chips. Did you check to ensure the capacitor electrolytic didn't damage the logic board?

 

[Dinotech]

Visually no damage or broken electrical paths, but this computer for me not too familar to understand where is control points to check CPU voltages, etc. Maybe someone have control point circuit?
About ROM's im talking because after cleaning i made a mistike and insert it in wrong side (empty pin be on right side in socket, not in left).
Second reason why i pointing to ROM - when i remove ROM chip from first Classic (M0420), computer showing checkboard. After inserting ROM back - working again great.
Here is my Classic II cleaned logic board picture, maybe some idea what i need to measure to understand damage?

 

[Dinotech]

I cheked RAM's - when inserting RAM modules in other (M9420) memmory extension slot, other computer normaly loading Mac Os 7.0.1 (without memory extension can't load that version), and work fine. But when inserting A0420 original RAM modules in broken Classic II - the same chckboard. So - problem not in RAM modules (maybe in slots, but i can't see any isues when looked).
There is "chesboarded" logic board foto from bottom side. Maybe is some idea - how understand, where is problem or from where start searching it.