Strange Interference Problem - Solved

Periodically, my Tablo would lose most channels for a few minutes at a time. Using a quiet section of the AM band on a portable radio, I was able to trace it to static generated by my refrigerator. No type of static filter cured the problem. After trying many ideas, it turned out to be that the vertical post between my fridge and freezer compartments was dirty. There seems to be some mysterious sensor to tell when the door is closed, that was generating massive static because the door post was dirty. I cleaned it and the static was gone, never to return.

Weird, right? But the use of a quiet part of the AM band as an interference detector was very useful. Now I can go around my house and see exactly what is generating static.


Bob, I want more detail, but you probably think you were very clear in describing your test. So, let me try. You got a portable AM radio in hand, tuned to some non-existent station then wandered around until you heard massive static. As you got closer to the frig, the static was immense. So you tried things (cleaning) until you managed to make the sound go away.

Thing I don’t understand is that AM radio waves are on a different frequency than TV broadcast. So for your method to work, your frig must be transmitting at multiple frequencies, which I guess is possible. I have no knowledge of signal analysis.

I am not trying to undermine your test. I just want more information as we all have failed recordings then we check the station and it is crystal clear. If you have a test, that can help find the problem, I am all ears.

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I can’t make sense of this either. Your description of my process was correct. I won’t go into the myriad things I tried before cleaning. The AM radio test found a bunch of things that created static on the AM, like my TV and flat screen monitor, and most things electrical. Except for the fridge, none of these affected the Tablo. The fridge also killed reception directly through the TV, using a separate antenna. I unplugged the fridge many times, and the interference always stopped and returned when I plugged the fridge back in. All of this only happened when the compressor on the fridge was running, which explained the intermittent nature of the interference.

Believe me, I can come up with no rational explanation why cleaning the door of my fridge would stop interference on my TV, but it clearly does. Apparently there is some sort of EM device so the fridge can tell when the door is closed. The switch that controls the light had no effect. When the door is not closed sufficiently on the freezer compartment, the ice maker won’t work, and there is no visible switch that makes this happen.

True, AM and TV are different frequencies. All I can think of is that the interference from the fridge covers both frequencies. You are right to be baffled; I certainly am. But the AM radio test was very helpful, and I think some Tablo users might find it helpful.

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It turns out there is a sensor in the freezer door to turn off the ice dispenser in the door when the door is even slightly ajar. The hinges on my doors had gone out of adjustment and the fridge compartment door was too close and was causing the sensor to produce static. The cleaning I had done apparently was somehow beneficial, but did not solve the problem. Adjusting the hinges to restore the spacing between the doors did solve the problem.

Still strange, but much less weird than the cleaning hypothesis. Still, without the AM radio static detection system, I never would have solved the malfunction with my Tablo. BTW, my direct connection to my TV through another antenna always showed the same behavior.

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I know we have radio interference when my wife’s fillings broadcast the lastest farm report.