I have a pretty old Sony trinitron maybe 7 years old or so. I've been having problems with it lately, it acts up most of the time (I would say it acts up about 98.9% of the day) and its starting to get on my last nerves. The problem is the t.v. will buzz, then the pictures turn gray, then it blanks to grey with the picture still there and it does this repeatedly for hours at a time. Also its make an anooying sound.
Very common. 98.9% of the time it will simply be due to multiple dry soldered joints to main board and Tuner/IF modules.
Check especially voltage regulators.
Usually need to remove the main pcb from its plastic carrier to thoroughly inspect the soldering. Very often the poor connections are hidden behind the plastic moulding.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix televisions.