KP-51HW40 Sony 51" Fades to blue screen
The service manual on page 8 shows how to adjust the Red/Blue/Green screen voltages. To get to the adjustment board, take the front speaker grill off (two screws at the bottom left and right) and set it aside. No need to disconnect any wires. Then remove the plywood board with 4 screws that exposes the screen/focus adjustments. The top 3 adjustments are for focus, and you need not mess with these. The bottom 3 adjustments are for Red/Blue/Green screen voltage rough adjustments. My screen showed red lines, so I had to turn the bottom right adjustment with a philips head screwdriver just slightly until the red gun retrace lines where no longer visible.