If you do the search GRJ recommends, there's a great summary post of what to try for the PS2 5V board set.
Buried in that is reference to ChipQuik which is a low-temperature (think "Lead") alloy which I use when removing the SMD audio amp on the PS2 3V board. Everyone has their favorite method for de-soldering but I find ChipQuik useful albeit somewhat expensive. You'd use maybe 1 inch of the stuff to remove the TPA2000D1PW. There are plenty of youtube videos and such to see it in action if you're not familiar with it.
As GGG points out, the heyday of PS2 5V board repair was like 10 years ago. My memory isn't what it used to be but I'm pretty sure I was able to use ChipQuik to separate the 5V board pair. But the question is what exactly do you do once you have the boards separated? Without a definition of the interconnection pins what would you do first? If you only have a few board sets, I'm leaning toward the "lost cause" school of thought. But someone once said that lost causes are the only ones worth fighting for...or something like that! It sounds like GRJ has a box of non-working 5V board sets. If you could get your mitts on some of them for little or no cost, then I'd think it might be worth the effort.
