I've got an atari 800 XL that is broken - when I power on, there's no reaction. It seems there is at least something sent to display, as TV detects a signal, and turns full black.
The chips are soldered in, not socketed, so I cannot remove and swap them with working ones (And I do not have any spares anyway, so that kind of diagnosis is impossible in my case.) There are no visibly broken parts, capacitors are not bulging, and no IC's turn hot, so there are no obvious faults at play there.
I do however have a multimeter and logic analyser (sadly, I do not have an oscilloscope), but no knowledge as to what should I check, what voltages should be at which points, and what signals chips send on which pins.
Is there any sort of guide as to what to check in such case, or anybody with the know-how can please share the knowledge?
(If that changes things, there's a memory mod installed that I cannot, and won't even attempt to remove)