Couple of things.
Monoprice (site supporter) sells a 5x1 switcher (product ID 5081) for about 40 bucks shipped. I can't vouch for it's quality personally but it gets good reviews on this site. I have just ordered one since my LC-45GX6U has whitescreened on me as well.
Here's my story.
In early April my machine whitescreened. It was bought new in December of '05, has not moved from its original set up location and prior to this it experienced maybe a half dozen occasions of unusually long delays starting, those events occurring across its lifetime and not any more likely now than when it was new.
I spoke with Sharp and they referred me locally. The local tech wanted the box, the monitor and the cable brought to his shop which was a showstopper since the cabling is buried in a wall. He would service it at my home but after he quoted a housecall I opted to reassess.
Instead I got lucky and found a TU-GD10U-T AVC and bought it.
I swapped out the box and still whitescreened. After pulling the monitor down off the mantle, disconnecting power and cabling and then reconnecting it, the system fired right up. At that point I thought that a connection fault had been the gremlin and though I kicked myself about buying the second box, I had the machine back so I called it a win.
Last week it whitescreened again.
I repeated the connection ritual but no change. I disconnected power overnight from both the AVC and the monitor but no change. Finally, I recalled my original AVC from the garage, swapped it back in and the machine fired right up.
We are running now, but I can't live with the likelihood of an ongoing issue.
My HTPC is wired into my den and bedroom and the Sharp, of course is in the LR so I have no back end to run it in the absence of an AVC. I'm going to throw together a Shuttle with an HDCP compliant ATI vid card, probably an ATI Wonder with onboard tuner. I'm hoping that when the Sharp fritzes again, which it will, that I can push the Shuttle, a DISH 622, and my PS3 through the switcher.
The thing is, lacking the AVC the monitor stands alone without factory display tuning capabilities or a variety of other bells and whistles. Pity to lose all that.
I read somewhere that that a common culprit in this model is the DC/DC converter board resident in the AVC. It's a screwdriver swap, since it's the top board on the left side of the AVC and hence accessible. Part number is # RDENCA089WJZZ but I haven't found one yet. If you do, and they have two, let me know.