So, a few weeks ago, my friend found an attic full of old Apple computers and most of them had problems, most of which I could fix. However, I started working on the Macintosh SE he found and it has a rather peculiar issue. Here is a video of the issue happening:
When we first pulled it from the attic, it would boot up fine but then it would shortly hard crash in a way similar to what the video shows. After a while, it wouldn't boot at all and all we got was what you see in the video.
Last night, I opened the case to start troubleshooting. The first step I tried was disconnecting the hard drive. After I did that, a strange series of events happened where the computer wouldn't boot, I'd cycle the power switch, it wouldn't boot, I'd cycle the power switch, and then it did successfully boot. I turned it off, reconnected the hard drive, and it booted normally and did not crash even after several hours of being powered on. Then I came back to it today and, lo and behold, back to the issue depicted in the video.
So it's an inconsistent problem, sort of, and I'd like to fix it. I'm an electrical engineering student so I have a good idea of what I'm doing. Is there a capacitor or capacitors that were prone to failure on the analog board or in the power supply? Replacing capacitors has resurrected Macintoshes for me before, so I hope the problem is that simple. Either way, I'm at a stopping point and could use any kind of input anyone can offer. Thanks!