Weird Monitor Problem

[mclaren85]

I have a very very strange problem and I really need your ideas.. My monitor always blinks for about 1 second whenever I turn off/on my light. Fearing this may cause harm to my newly built Ryzen system, I decided to buy a top quality line interactive UPS from Schneider Electric. I connect everything including speakers and monitors to ups. But the problem goes on..
In the end, I isolated the ups completely, unplug from the mains, means there is absolutely no connection with outside world, but the problem still exist.. I turn on/off the light, and monitor blinks even there is no electrical connection..
What are your ideas? What can I do? And most importantly, does it harm my pc??

 

[Bill_Bright]

Sound like EMI/RFI (electromagnet/radio frequency interference). I would start by making sure the video cable between the computer and monitor is securely fastened. If it is, then replace it with a different cable.

What kind of light is it? Florescent lights are notorious for generating RFI. Make sure the light is securely tight in its socket - better yet, replace the bulb. It could also be loose wiring in the switch or fixture. This should be checked as that could pose a fire hazard.

BTW, nice troubleshooting technique, isolating everything by having it run only on the UPS batteries!

***

As a side note, since the problem is there with the speaker connected to the UPS too, I recommend you move the speakers' power connector off of the battery side of the UPS. Beside the fact you don't need audio during a power outage, audio amplifiers can draw a lot of power and drastically reduce your battery run time.

 

[mclaren85]

Most probably it is about Emi yes, but how could a stupid tiny electrical line could emit that kind of radiation? I'm thinking about wrapping the DVI cable with aluminium foil to protect any interference. will update the result.

 

[Bill_Bright]

If wrapping the cable with foil helps, you need to buy a new cable as that cable (or one of its connectors) is clearly bad.