Hi, it's me again.... For last post, I test the power supply carefully, and it finally works well. 5V and 12V both works well. The Macintosh SE DID work. Unfortunately, there's a floppy disk icon with question mark on it. I tried using external hard drive, internal hard drive and floppy disk. All of them can't work. First, I tried to make a floppy disk with system in it. I make 6.0.7 and 6.0.8 in it, with 800k floppy disk. But once I insert the disk, it soon come out and replaced the question mark. When the computer worked well, there was a 6.0.7 in internal drive, but now, it also doesn't work. For external drive, I also make 6.0.7, 6.0.8 and 6.0.9, all of them can work on emulator, but can't work on this Mac. I tried to find which chip is broken, but it seems SCSI, floppy are two separate chip, I think it couldn't be broken at the same time, and the 5V and 12V also can be detected. What should I do???