PowerBook 520c Power Supply


My PowerBook 520c has served me faithfully over the years, however, I recently noticed that when I went to move the power supply, it was dead cold (not usual). After checking to make sure it was plugged in, which it was, I turned on the laptop and it started fine. Upon closer inspection, I noticed the power supply making tiny crackling noises. Will this thing catch on fire if left plugged into a wall socket? Where can I get another power supply? I *REALLY* need this thing as it is my only Mac with a true serial port. I only use it for once in a while portable computing, but mostly to load/save programs from my Hewlett Packard HP48GX calculator. I am still using the original HP serial interface kit for the HP48/Macintosh. It uses the Kermit protocol/program to transfer programs/data files.

I know that electrical components can fail after many years of use. I would like to fix this myself if it's possible/feasible. Is there any way I can crack open the power supply case without destroying it / making it unsafe to use?

Would Kermit or another program be able to transfer files to/from an HP48 with a USB to serial port cable adapter?