Thanks for your reply!
The problem I have is that some of the RAM (8chips) are soldered onto the logic board. I probably should have mentioned that I have tried with the RAM daughterboard removed and I don't get the checkerboard, just fine horizontal lines.
I can rework the RAM if required, I just want to be damn sure it's that before breaking out the hot air gun and buying chips. Based on the RAM chips I think it is 1024KB of onboard RAM.
I think I'd better break out the logic analyser and scope, see what the RAM and address/data lines are doing too. I just need to figure out a way to get it easily accessible as the power lead from the analog board is short, so getting to where I need is hard, even with the logic board out of the machine.
Ok guys update, was able to fix the LC 520 Board and work like a chap...put it in on the Color Classic, Speaker work, everything works...now, original CC board recap, but still no chine...the unit boot and with headphones you can hear it...sometimes after shutdown, will no boot back...any idea on that board what can be the issue.