My Sony 36XBR450 has started showing some ugly symptoms of late. In bright white areas of the screen there is a very distinct grid pattern showing through. This shows up on all the inputs and on all brightness and color levels. Any thoughts on what could be causing this?

My first thought would be some kind of A/D, D/A conversion problem. The pattern seems to be scan line oriented and worse at the start of the scan. The pattern seems to duplicate every X number of lines. Maybe a data bus not moving the 1's and 0's correctly. Buffers not functioning. I would recommend opening up the set and reseating cards as a first option.

raouliii - That's an excellent suggestion. I've been racking my brain trying to figure out what could cause that pattern and came up blank. I'll give that a try tomorrow morning and see what happens.

What happens if you change DRC settings (Interlaced, Cinemotion, etc.) if you have those?

jdre - I tried adjusting the DRC settings and it didn't make a difference. Any other thoughts?

I opened up the set yesterday, reseated all the cards, and dusted everything off but that didn't help with the picture. There were a couple other things I noticed that might help narrow this down.

1) In Twin View mode (picture by picture) the problem goes away.

2) I hooked up a second TV to the monitor out of the XBR450 and there was no evidence of the problem there.

With those two nuggets I think I can rule out the input chain so it looks like the problem is coming from something in the output chain.

... This shows up on all the inputs and on all brightness and color levels...Just to make sure we understand. You have tried rf (internal tuner), composite and component video inputs and the problem shows up on all?
....1) In Twin View mode (picture by picture) the problem goes away......It is not present on the screen as a whole and it is not present in either window, regardless of the input?

...2) I hooked up a second TV to the monitor out of the XBR450 and there was no evidence of the problem there.....Regardless of input?

I'll double check all of this after the holidays but my recollection is that yes, it shows up using the rf, composite, and component inputs, in Twin View mode it is not present, and the monitor out shows no evidence of the problem regardless of the input. The monitor out port isn't as telling as I thought it was though. I was going over the schematic in the service manual it looks like the monitor port is picked off before the A/D-D/A chain.

Happy Holidays!