Pc monitor goes black for a second
So is the monitor connected to a mains input that includes a ground connection? Have you checked that the ground in your home wiring is actually bonded to the real ground?You could have some faulty wiring causing a problem with your earth leakage currents.
Then you are wrong about something, how did you check this? Have you had the monitor PAT tested recently?As your computer does not reset there would seem to be nothing wrong with that and no danger to it. But connecting power supplies when things are powered up is a big no no in electronics as I have told you before.
but I still don't understand why the monitor goes black for one second.
The monitor goes black because something is disturbing the monitor circuit. It is not affecting the PC otherwise the PC would reset, as they tend to do at the slightest opportunity.The problem occurs when a second supply is connected. This second supply is floating with respect to the monitor and so when it is connected the ground of the power supply and the ground on the monitor are brought to the same potential. This causes a very short inrush of current which disturbs the monitor's operation. The result is that some protection circuit in the monitor shuts it down. Then the inrush stops as the two supplies are now equalised and the monitor comes on.Just as a test remove the LED strip and just connect the power supplies' negitave terminal to the rest of the circuit. It should still happen.I didn't ask before but I am assuming the monitor is a CRT one.
do you think that something like this:https://www.adafruit.com/product/2107should help preventing this problem and making my computer "more safe"?
Thanks for that, it is gives a better understanding of what you have, your construction looks quite good.I am not sure how much reliance to put on all those declarations of conformity on that power supply but the big one that is missing is the UL mark. It is not surprising as it is perhaps the hardest one to obtain with respect to a power supply. UL is largely driven over concerned with the device starting fires, hence the name Underwriters Laboratory, it arose from insurers wanting to minimise their risk. I do know that UL has a much stricter limit on the earth leakage current than some of the others like CE. I am not saying go for a UL rated power supply and it will solve the problem, they are a lot more expensive and the UL rating mark might be false on Far East designs. What it doesn't change is my guess that the problem is probably due to earth leakage and the best bet is to have things connected up before applying the power. I know this means powering down then up before making changes to things, but that is what you should do anyway. Even plugging a monitor into a computer that is running can damage things. Their are things you can plug into a computer when it is running, like USB but they have been specifically designed to be "hot swapable", these designs connect the power rails before connecting signals. I have a similar problem with the Raspberry Pi, you can't plug many things into the GPIO pins without resetting the computer. In the case of the Pi that is a bad thing, because its main storage is an SD card, and unexpected interrupts runs the danger of destroying the card. And being Linux the boot up process is not swift.
Suppose that there is an earth leakage,
how connecting things before powering up them all can be safier?
This will be my last question to not bother you.
Don't worry, keep asking about what you don't understand.