Ln52a860 has sound, but only black screen, no fuzz, no anything, like it is off.

That was the first thing we checked when ours had this issue. Had a tech come check it out. He said that it's the power inverters that supply power to the CFL tubes for the backlight. He can replace them for about $500 but there's no guarantee that it will be a permanent fix because the actual malfunction could be being caused by the panel itself . There are no replacement panels currently being manufactured for this model since it's so "old" (a little over 2 years!). I think we need to complain to Samsung! a $3500 tv when new should not be failing after only 2.5 years!

If you get a quick input blurb in the upper left corner when you first turn the tv on and maybe a portion of the screen gets backlight bleed light then quickly goes black (check this with the room really dark to be able to see it), it's more than likely the inverters. The unit has a failsafe that cuts all power to the inverters when it detects a malfunction and keeps them from powering the backlights. That was the first thing we checked when ours had this issue. Had a tech come check it out. He said that it's the power inverters that supply power to the CFL tubes for the backlight. He can replace them for about $500 but there's no guarantee that it will be a permanent fix because the actual malfunction could be being caused by the panel itself . There are no replacement panels currently being manufactured for this model since it's so "old" (a little over 2 years!). I think we need to complain to Samsung! a $3500 tv when new should not be failing after only 2.5 years! If you get a quick input blurb in the upper left corner when you first turn the tv on and maybe a portion of the screen gets backlight bleed light then quickly goes black (check this with the room really dark to be able to see it), it's more than likely the inverters. The unit has a failsafe that cuts all power to the inverters when it detects a malfunction and keeps them from powering the backlights.