Hey, I just got the chip in the mail this morning, and I decided to do it myself. I worked on getting the first chip out for 3 hours, and then I put the new one in started it up and it worked! I was so amazed and happy! It had the disk question mark symbol as usual and the mouse worked fine. But when I put the floppy disk In the drive didn't start doing anything. So I turned the computer of and wiggled the plug to the floppy drive a little and pushed it in on both side to make sure that both connections were fine, I turned the computer on and there was a resounding SCREEECH and then smoke came out of the pcu! I have a new analog power board in the mail (Ebay) along with a floppy drive. But does anyone know why this happened?
Oh dear. Rotten luck. Glad to hear the RAM chip replacement worked. But where did the smoke come from? Do you know where? If possible, take a photo of the top section of the analog board.
There are two silver heat-sinks on the top edge. If one is a blue-purple color, then the Flyback transformer is definitely shorted.
It's usually possible to clean and re-lubricate the floppy drive. The floppy drives do have a tendency to lose the felt that places gentle pressure on the disk read surface above the head.
Other issues might be bent pins on the floppy drive connectors.
Whilst it's a terrible coincidence that the flyback transformer has shorted, and they are/were a common problem with the analog board, a part of me is wondering if something else shorted as a result of an accident. I'm not trying to be accusatory, just trying to help, you understand.
One thing I did myself was to accidentally hit the circuit board of the tube neck on a MacSE. It cracked the tip of the tube and caused a horrible squeal when I next powered it up. Luckily, I had a spare tube and was able to repair the analog board.
