I don’t know how far you were from the transmitting towers when you were having this issue but I suspect the 1 to 4 splitter pictured may be contributing to the problem. My bedroom tv will work off of a weak signal while the main tv refuses to pick up anything or is really marginal. In my case the bedroom tv runs directly off of the black wire going to the 1 to 4 splitter and the main tv is plugged in the front of his coax assembly pictured. In this case each tv is getting about 50% of the antenna signal.
In your case there is no tv connected to the front of this coax assembly so the 50% signal is going to the 1 to 4 splitter where it is further reduced. In this case to 25% of the incoming signal so the actual output from each port will be approx. 12.5 % of the antenna signal (50% divided by 4). The working tv which I am “assuming” is directly connected with no splitters may be happy with 12.5% however the other two tv’s are running off another splitter so each will be getting about 6.25% of the antenna signal. This will be too low if you are distant from the towers.
You need to replace the 1 to 4 splitter with a quality 1 to 2 splitter even if it is not the actual problem in this case. Now the signal going to the currently working tv will be 25% of the antenna signal and the other two tv’s sharing another 1 to 2 splitter will be getting 12.5%. Still “only” 12.5% but may be enough again not knowing how distant you were.
The other issue with the 1 to 4 splitter is that the unused outputs are not terminated and while not necessarily related to this problem can cause a noisy picture on the other tv’s.
The other 1 to 2 splitter I assume is in the wall behind the closest non-working tv to the coax assembly pictured so I would pull the plate and have a look there and check for tightness. They wouldn’t actually run the coax to the farthest tv first, would they?
Please refer to the Channel Master link for information about splitters.
https://support.channelmaster.com/hc...2HD-CM-3213HD-
Again may not be your actual problem but splitters can be your enemy when there are too many or as in the case of the 1 to 4 being misapplied.