Posted in the wrong spot before- my apologies.
Just got two fully socketed 600xls. Using a new power supply, one 600 is not working and I swapped all chips out (and thus reseated). The good 600 found three bad chips from the bad: ANTIC (CO21697), CPU Sally 6502C CO14806 and the CO60472-D (Delay). After putting them aside, I put the GOOD versions from the working board into the bad hoping I'd just need the three chips to fix it. No dice. Now, it powers up to an odd screen (see pix) I was hoping not to desolder willy nilly.
*I followed the Black screen/Red screen guides from http://atari.boards.net/thread/893/black-screen-problems-fix-checklist so all steps from Star Raiders to channel 2-3 moving tried.
Anyone know my next troubleshooting steps to try with that screen on a fully socketed 600xl with all tested and working chips? Does knowing those three chips failed reveal anything from the board's unknown backstory? Bad PSU? Loose socket? Bad crystal?