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My LNT-4081F will randomly drop a HD channel and shift it to another channel. For instance, channel 30-1 (NBC in my area) will suddenly and quickly pixelate and I'll be viewing a different channel, typically 90-1. If I hit the UP channel button on the remote once, it goes to 90-2 which is now the original program that was on 30-1. If I try to get back to 30-1 by manual selection on the remote, it's gone (no longer on channel list)even . After a while, if I stay on 90-2, it will suddenly drop out and then I can get back to 30-1. And, there's no longer any program on 90-2 (missing from channel list). I found out the 90-1 correlates to 8-1 (ABC), which is also gone at the same time.
If I do a channel auto re-scan when I first lose the channel, it will pick up 30-1 in it's correct place (after an excruciating long 25 minutes for the scan).
I thought it could be the signal dropping out but I would think I would just get a "lost or weak signal" message when that happens and the channel would at least stay on the channel list.
Some other things: I have Comcast analog cable service. The shifting channels are "pass through" HD channels (like NBC and ABC). They aren't the occasionally scrambled channels like PPV that sometimes pop up on a blank channel. I have another Samsung LCD TV (ln-t2342) in the house and it doesn't have any problems (at it's at the end of a long coax run with a splitter before it). I also have a Philips DVD recorder with QAM tuner at the same point as the 4081 and it doesn't have the problem either.
So I'm thinking my mainboard may be defective. Any advice?