Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.
There are 3 boards that split the TV screen into 3 sections from the top to the bottom.
I've highlighted them in yellow. Can you tell where this line is located on the screen and determine which board has a dead output signal?
Multiple lines in ONE section would indicate that the SU board's IC that drives that section has failed and the board needs replaced.
To an extent it is common simply because there's over 200 volts coming off those ICs , and high voltage ICs fail more than low voltage ICs do. I would have expected that.
You may have to special order it due to the size of the TV set. Very few people own a 103 inch TV set, so spares aren't in high demand.
Part number is TNPA4030
Yeah, it does look like it's a custom order. Do you have any nearby Panasonic Authorized servicers that could order it for you?
That would be my 2nd option.
When major suppliers like Charles Hyde and Son don't list it, it's a custom order.
Try Googling TNPA4030. You may find a supplier in your region that isn't coming up on my region.