appliances interfering w. tv/computer monitor - what to do

Jul 24, 2006 3 Replies

So, I have an LCD tv hooked up to a Scientific Atlanta cable box on one outlet. On the same circuit (but different outlet), I have a CRT computer monitor plugged into an APC Backoffice UPS (into which the computer is also pluged in). On a different circuit in the kitchen are items such as the microwave and toaster oven and the fridge.



So, if I run the microwave, the picture on my computer CRT is quite shaky and I get quite a bit of audio hum in the sound from the cable box/lcd tv. If the toaster over is running, the crt is less shaky, and I don't notice any audio hum. If the fridge is running, there is a tad of shakiness (could be mistaken for poor refresh rate on the crt). It's unclear if the water heater is causing any problems, and the window AC does not seem to be causing noticable problems, either (tho, it's upstairs on a different circuit).



So, any thoughts on what is going on and what I can do to eliminate the interference problems? I'm guessing not a short to ground since no circuit breakers are blowing. Is there some sort of grounding loop? Some sort of inductance going on? Something I can test for with a multimeter and then go to the apartment people and say "look, this needs to be fixed, here's the evidence"?



Thanks in advance!



******************************** David William Botsch dwb7@cornell.edu ********************************

Thanks. I'll give that a shot (wish I'd remembered to bring home the multimeter from work, today). Though, I find it odd that the circuits would be overloaded since they should be rated for what is on the breaker (and we're not talking anything abnormal here in terms of usage... mostly not even all this stuff running at once.

******************************** David William Botsch dwb7@cornell.edu ********************************

Another possibility is that there's a wiring problem with an open neutral, ground shorted to neutral within the wall, or open ground. Some of those wiring problems can be tested with one of the little $1.49 three-LED testers that you plug into the wall socket.

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