Before making any measurements, be sure to first unplug all the TVs in the apartment from the network, and then cables from them.
If we are talking about the collective antenna, and the splitter in the get with the ohmmeter to the opposite end of the cable will fail. Will have to measure from the side of the plug. Check the resistance between the ring and pin plug. It should be several tens of ohms, due to the presence inside the amplifier, located in the stairwell, a matching resistor. If it is close to zero, a short circuit, and if close to the infinity open.
Work much easier in that case if the user has both ends of the cable. The simplest case occurs when the cable is connected to the indoor antenna. If it is equipped with an amplifier, disconnect power. Remove the antenna cover on the connection cable. Then using ohmmeter will ring first braid, and then the copper core of the cable the resistance should be close to zero. The resistance between them should be close to infinity.
When the cable is so long that connect an ohmmeter to both of its end is not possible, using this technique. Unplugging the cable from the antenna or a splitter from the plug, connect the ohmmeter between braid and inner core. It should show infinity. Now go to the opposite end of the cable and jumper. Go back to the ohmmeter — it should show a resistance close to zero.
To determine the location of damage, inspect the cable throughout its length. It is possible that you will find on it a dent — this is the place you need to carry out splicing. If the dent is not found, please connect it to the cable on one side of the ohmmeter. If earlier it turned out that there was a cliff on the opposite side, install the jumper, and if circuit, do not install it.
Asking the helper to monitor the ohmmeter, walk across the entire length of the cable, affecting it mechanically. Once the assistant will report on the change of the readings of the ohmmeter, stop and repair the damage. Note that damage may be more, and if eliminating one of them did not give result, try to find another.
After elimination of damage the ohmmeter and remove all jumpers and connect the cable back to the antenna (or splitter) and TV.