Chosen Solution
My 55” Toshiba has a line going horizontally across about 80% of the way down the screen. Everything below the line is normal brightness and color, whereas the top portion of the screen is very dark. Happened randomly after not being in use for 7 days. Powering on and off the TV and all devices did nothing. The line/box is there even when no devices are plugged and appears on every input.
Update (07/06/2020) Brought it into a local shop because I was busy, they said it’s an issue with the tcon and that it can be repaired. Thanks.
I would check if there’s a partial LED array failure, especially if the TCON board doesn’t help. I have seen it where you lose some of the array on one strip, but not the entire array before and it looks like a partial failure since you lose enough of them the entire array is dead or compromised. In most cases with multi array displays like this, you lose one but not the others and it’s half dead - which is what happened here. In your case, it looks like a partial failure where you have 2+ arrays, and one or more has completely failed. Partial array failures are unique in that you have a unusual failure like most of it works, but there are noticeable backlight performance issues like part of the display being dead while the rest works. Generally speaking when you see issues like that, it can be repaired with donor strips. The issue is replacing the panel costs more then the TV is worth most of the time, so there is really no economical way to change the screen; it’s usually only viable if you change the strips out as a set with known good ones - new or used from a cracked panel.
