Fuses blown and PC backup power … and a mystéry

Thread Starter

minutepapillon

Joined Jun 2, 2017
8
I must admit it, what happened goes beyond my logic, so I need help to understand. My two computers and the peripheral devices are powered through an UPS (backup power). I use 3 power strips to power all these guys.

This morning I noticed that the loudspeakers of my PC where down. After a few tests ...conclusion : the transformer is dead (it has no ground pin). So I turned on my two bigger loudspeakers (KRK Rokit 5), ... well I couldn't ... After a few tests ... conclusion : the fuses are blown. I changed both fuses with the spare fuses, the loudspeaker turned on 10 seconds and then ... blown fuses again. I thought that there was a problem with the loudspeakers.

I found new pc loudspeakers. I plugged their transformer in one of the power strips (it has no ground pin). It worked, 3 minutes, but the volume was low and an ugly overdrive occurred in my music. Then the transformer blew up too.

I started thinking that these events were connected (I am a fast thinker) ...

I measured the tension : 237 volts (after UPS and before and in several other plugs in the house ... which is normal in France (where I live) The state electricity company told me that tension ins considered normal up to 250 volts.

All the other devices inducing computer work perfectly. ... but I wonder if it is really reasonable to use them.

Tension between ground pins (UPS, powerstrips after UPS, and house) :
I can't detect any in alternating current. (my voltmeter has a 200v min caliber ...)
In continuous current one power strip has 2 mV with the others (the one with computer n°2 ... this tension disappears if i unplug it)

Anyway I have no explanation (UPS ? power strips ? ) ... and i need to do my work. I know that life would be worse if the Great Plague was back but i will be grateful to any person able to give me a clue.

Thanks, Nicolas, France
 

AlbertHall

Joined Jun 4, 2014
10,549
Could you draw a quick sketch of the wiring - UPS, powerstrip, computers, speakers, and fuse locations and post it here.
Does everything except the speakers work normally?
 

AlbertHall

Joined Jun 4, 2014
10,549
If PC2 still works reliably then the socket strip feeding it (which also feeds the speakers) is OK.
Given that, and if all the speakers are rated for 230V, it seems that the speakers failing at the same time is coincidence - it does happen.
 

Thread Starter

minutepapillon

Joined Jun 2, 2017
8
Thanks Albert
Well, the problem is that we have here 7 events occurring the same day ( 3 transformers blown and 4 fuses) ... and in the same part of my local innstallation ...
It's hell of a coincidence. What do you think ?
 

djsfantasi

Joined Apr 11, 2010
6,950
In the power strip feeding PC2, can you measure the voltage at each outlet and post them. Let's assume the outlet feeding PC2 is outlet 1, the next outlet is outlet 2, and so on.
 

Thread Starter

minutepapillon

Joined Jun 2, 2017
8
I have measured the tensions in the outlets of the house (237V).
Now i could remove the ups but I have no more fuses or transformers to try any of the loudspeakers. (They are all dead).

... and, to detect the problem, I would like to find a new way that would not involve the destruction of my devices. :)
Thanks
 
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