Topic: Fireface UFX+ / Electrostatic discharges

Hello, fellow RME users!

I have a somewhat strange problem with my Fireface UFX+ but, to be fair, I am pretty sure it has nothing to do with the device itself. I would nonetheless be very grateful if someone familiar with the curcuit of the UFX+ or someone who is a bit more versed with power problems could maybe point me in the right direction.

I am working in a very old building in eastern Germany which has a somewhat sketchy and unstable electricity. I am sure the wiring is from GDR times. I suspect my problem might have to do with that, which is why I am mentioning it.

With my UFX+, I regularly get what seems to be electrostatic discharges over both headphone outputs. It happens whenever I move in a certain way with headphones in my hand and it happens very frequently. I have found the source of the electrostatic charge (it seems to be created by my office chair, so I can reduce the number of discharges by simply putting a pillow on it).

Not only is there a loud click when that happens, the microphone input of the UFX+ also lights up shortly to indicate it is getting signal. Additionally, sometimes, the computer loses the USB connection to the device whenever that happens which is obviously very annoying.

I have two UFX+, and it is the same with both devices, also, I have several headphones of the same type, and it is the same with all of them also. Therefore, I am inclined to outrule that it is a problem with the devices used.

After much trying around, I have found that all of these problems disappear when I ground the device using a ground plug (a special power plug which only connects to the Schuko ground which is connected with the metal housing of the UFX+). Of course you might say that I could be happy know but I wonder what the reason is.

Since I am not very versed with all things electricity (as you might tell from my post, sorry), my questions would be:
- is it safe to operate the device like that?
- since this is certainly not how things should be, I wonder if something is seriously wrong with the wiring of the house electricity. As I said, I don't know much about these things, so does any of you have an idea what to look for? Of course I would not do anything myself but hire an electrician, but at the moment, I would not know what to ask for exactly.

I have an Octamic XTC in the same rack, and its headphone outputs do not show any strange behaviour. It's only the UFX+.

Thanks for any thoughts on this, and once again sorry if this might be a strange problem and maybe I am looking at things the wrong way to start with.

Best, Christopher


Re: Fireface UFX+ / Electrostatic discharges

There is something unlogical in the description. The UFX+ is connected from PE aka ground/Schuko to its housing via the IEC power cable (Kaltgerätekabel). The additional ground cable is not needed at all. If that one changes something then the original power output/cabling must be faulty or incorrect.

Matthias Carstens

Re: Fireface UFX+ / Electrostatic discharges

Hello MC, and thank you for the prompt response.

OK, I understand, that is strange then, I had tried several Kaltegerätekabel right in the beginning and that was not changing anything, but I just noticed that my ground cable is in another multi-socket, maybe one of them is indeed faulty.

Or I have "accidentally" changed something else in my setup without paying attention which was the real fix then.

I'll investigate further.