I will share some wisdom an elder engineer shared years ago. Ready? "Replace the cheapest part first" when in doubt of what part to replace next.
Diagnosing to the component level is tough without spares to swap in. And diagnostic gear for such machines are usually many thousand so that's why they send such off to service depots or just swap parts until they find it.
Good hunting,
Bob
Ladies&Gentleman,
My lcd tv shows two white colored thin horizontal lines in the bottom half of the screen when dark(no picture on). When video on, these lines go greenish-black.
First of all, I ordered and replaced a new T-con from ebay. It never helped. I realized I did a poor troubleshooting because I found most threads from google pinpointing to a defective T-con. When I unplugged two ribbon cables coming from the panel into T-con, two black horizontal lines still appear in the white display. That means that the T-con is good.
I verified the health of capacitors in power supply. no burnt, no bulged and no leaks. The inverter looks ok since backlighting still performing well. The main board (video card) seems to be ok since video does not show any issues except those black lines.
I am frustrated that I am not able to figure it out but i learned a great deal of knowledge in troubleshooting a defective lcd.
I really appreciate your great help in solving the issue.
Thanks in advance

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic