TV Picture Flashes Off & On

Not sure if my problem is the same as others. We have a 65" Visio TV (3 years old), wireless DIRECTV (for 5 years), and Sony Home Theater Receiver (3 years old). The tech hooked it all up when we got the DIRECTV. The DIRECTV cable comes from its wireless box to the receivers "CABLE IN" connection port. Then a cable from the TV is connected to the receivers "TV IN" port.

We are on our 3rd DIRECTV BOX to the TV & RECEIVER in about a year. While watchin tv a couple hours, the picture starts flashing OFF (black) and then on about every 3 to 8 seconds. Sometimes it stops when we do a RESET on the box and sometimes that does nothing. I have also turned off the TV a couple minutes and sometimes that helps & sometimes NOT. We only watch news live and otherwise we only watch DVR recordings. The flashing happens watching the DVR recordings, "BUT only on this one TV". We have 2 other TVs in the house with separates "box" connections and they don't ever have this flashing problem. So that eliminates the "main" box from being the problem. We have had the tech out to replace the box to the TV 3 times in 2 years and he claims the problem is the receiver which I do not think is the problem, BUT the problem does only occur with the TV connected to the receiver that we have had for about 3 years. We are "baby boomers", so we did not grow up with electronics and computers. So we need someone to walk us through an answer to our problem in a way we will understand. Please, contact us at at