Yes. Good thought.
I ordered one of these off of ebay:
Pioneer PDP-4304 Video Processing Board AWV2098 (ANP2072-D, PDA-5004)
It showed up Saturday. I haven't installed it yet. Still, even before trying it I've come up with a partial solution. Even with the - apparently - fried board, there's still a DVI input for video and standard audio jack on the monitor itself. In order to at least not waste the big plasma, I got a mounting bracket and moved it from living room to basement for an Xbox. I got an HDMI to DVI converter cable, and then a little box on Amazon that converts optical video out to the standard audio plug, (I think it's 3.5mm or something.) This actually works to get video and audio from the Xbox to the Pioneer; though you have to change audio settings on the Xbox to something simple. It was on 5.1 and just gave me a nasty noise of some sort. I figured it was worth spending $50 on some cables to see if I could save - what was back in 2007 or 2008 - thousands of dollars worth of monitor. (Before having to actually PAY another couple hundred just to remove it.)
Meanwhile... I've replaced that living room unit with a Sony 900F 55" and we're going to cut the cord. So in the end, this has helped force us to being cord cutters. The new gear will get paid for over two years based on cable savings alone. We're also going to go with TiVo, which isn't strictly necessary, but will make it easier for family to use a single simple remote. Now, for the Pioneer, if the new card works, I'll be able to put composite video into it. Which means I could one day hook up a remote TiVo mini into it. (I'm hardwiring cat 5 down to that area.) The end result might be that we'd have TV in the basement for the first time. The TV that had been there was never hooked up to anything other than the Xbox. But now, it would actually be do-able to get TV there, which would be nice as that's where the work out gear is.
Bottom line is this monster size monitor (well, to us it's huge anyway) has been at least partially rescued. Whether it can be further utilized is the question. Part of me is afraid of putting in the new board for fear of further damaging something that is now at least useful. But... you know... I'm still going to try it. : )
Who knows, maybe this solution will work for others. Bottom line is HDMI to DVI works. And optical audio to 3.5 headphone jack works.