Hey everyone,
I picked up a cheap 520STFM tonight. Got it home and fired it up an got a blanks screen with a yellow border. I opened it up and looks like there is a ram expansion which has been installed.
I decided to remove the ram expansion. I have desoldered all wires attached to the boards. The header board that is attached to the shifter is soldered directly to the motherboard so I have left that in there. I suspect this should not be an issue.
Anyway I still have the same issue.
I have reseated all chips that are socketed also.
Any ideas of where I should start looking for the issue? I would really love to get this ST running again.
(https://forum.8bitchip.info/proxy.php?request=http%3A%2F%2Fi1138.photobucket.com%2Falbums%2Fn532%2Fjmicari%2FAtariST%2FIMG_0741_zpsdab8f871.jpg&hash=6fdf625f2dcea8ed6e447509522e121b49fc76d0)
(https://forum.8bitchip.info/proxy.php?request=http%3A%2F%2Fi1138.photobucket.com%2Falbums%2Fn532%2Fjmicari%2FAtariST%2FIMG_0738_zps5ccf5693.jpg&hash=77045d77bc903b2aa5ae4aaea093e964464c5b9b)
(https://forum.8bitchip.info/proxy.php?request=http%3A%2F%2Fi1138.photobucket.com%2Falbums%2Fn532%2Fjmicari%2FAtariST%2FIMG_0737_zps8e75dffb.jpg&hash=aa51a7ecc79d701f95825b731a81cea44a7d65f5)
(https://forum.8bitchip.info/proxy.php?request=http%3A%2F%2Fi1138.photobucket.com%2Falbums%2Fn532%2Fjmicari%2FAtariST%2FIMG_0740_zps02bcc9fe.jpg&hash=6f6c827ea8f07f1155d28eb1445599e81a16f1b8)
(https://forum.8bitchip.info/proxy.php?request=http%3A%2F%2Fi1138.photobucket.com%2Falbums%2Fn532%2Fjmicari%2FAtariST%2FIMG_0739_zpscceaae38.jpg&hash=4b26038ccb41ceb6adb70e39a25b16f8bc75d357)
It may be that need to solder some wires, because usually, when install RAM expansion some lines are cut. But it is really not possible to give concrete instructions based on couple shots.
You need to bring that Atari to some expert.