This type of problem is known as a 'frame collapse' caused by a failure in the field output or vertical scan circuit.
This could be a failure of an integrated circuit (chip), fusible resistor or other soldered in component on the main chassis PCB which would require further diagnosis and repair by a pro. The parts would probably be cheap enough and the work shouldn't be too involved. Worth it if the picture was good, bright and sharp before this happenned.
If the set has been moved recently (stood on end or shaken about in a car for example) then there is a possibility it might just be a cable pulled out of it's socket on the main chassis PCB. This cable feeds the vertical scanning coils glued to the back of your 27 inch picture tube (CRT). If you decide to take a look then after taking the mains plug out of the wall socket (don't just switch off - play safe) take the back cover off and check that the plugs on the ends of the scanning wires hanging from the big wire coils around the neck of the tube are properly plugged all the way into their socket(s) on the chassis PCB.
While the back is off the set please BE VERY CAREFUL NOT TO TOUCH THE THICK WIRE GOING TO THE RUBBER CAP ON THE BACK OF THE TUBE. THIS CAN STORE 25000 VOLTS EVEN WITH THE SET UNPLUGGED AND GIVE A SERIOUS SHOCK.
It is a good idea to have someone else in the room while you work so if you should happen to touch anything live they can isolate you from the supply (house main switch) and call for help.
Fix the back cover back on before checking the set again!
Good luck
Chris Topping
Chris Topping, May 2006
