Picture flickers every few minutes
There are several possibilities. This model is based on CRT (picture tube) technology, and has a high voltage circuit. This circuit consists of three heavy wires, one from the side of each picture tube (red, green and blue) going to a single connection block. There is another heavy wire from this to the high voltage transformer on one of the circuit boards.
First, unplug the set, and wait 20 minutes to make sure everything is cool and residual high voltage charge has drained away. Check the wires at the connection block to make sure they are not loose. There is usually some sort of retainer clip to lock the wires in place, make sure these are not broken or unlatched (sometimes they get brittle with heat and aging). Frequently these are covered with a thick layer of dust held on by electrostatic attraction; gently vacuum this off. If all looks good, plug in the set, and wait until it's dark outside. Turn on the set with the room lights off, and look at the high voltage parts. If you see a blue corona glow or sparking, that part has an insulation breakdown problem or a bad connection. It is normal to see an orange glow at the bottom of each picture tube, and you would also see the three colors of the picture coming out of the tops of the picture tube. WARNING: do not touch the interior of the set while it is on, especially not in the dark.
Another probable cause is a cracked solder connection on the power/deflection board (the one with the high voltage transformer on it). If the flickering is one color rather than white or a momentary darkening, the problem is in one picture tube circuit (yellow -> blue dropout; ->cyan -> red dropout; magenta -> green dropout). The picture tube circuit includes not only the high voltage (second anode) section, but also the picture tube drive connection on the base of the tube all the way back to the video processor and switching circuits.
RCA D52W20 52"...
on Apr 17, 2015