Just a heads up, I just saw this on the news about the slims AC adapter causing a couple house fires. There's a recall on it (free replacement)
"The affected AC Adaptors were packaged with the SCPH-70011 and 70012 models of the PlayStation®2 entertainment system sold after October 2004. Only AC Adaptors manufactured by Hipro Electronics identified with a serial number that begins with the prefix ”F3” within a certain date range are included in this replacement program."
Playstation.com (North America) AC Adaptor Recall Check
I have yet to check my own system but I thought I would post this notice here before I forget.
Thankfully the AC adapter is external on the PSTwo and you don't have to return the whole system (which could be a problem if you modded it).