Weird network card problem (Electrical)

Hello, I'm not an electrical engineer so I wanted to get your opinion also about this strange situation. 3 weeks ago the factory that I'm working for changed its UPS system.
Now 3com btx network interface cards (3c905b-tx) are not working properly (I get many request timeout when I ping different servers, I can't connect to shares). When I check with sniffer we get many CRC's and some alignment errors. It's weird because it's not working in the technicians room. It's working in my room. When I plug it to the socket in my room it's working (with the same network connection) but when I plug it in the technicians room it's not working. I've tried the network card in the new computers, but it's not working also (in the technicians room). I have tried as many 3c905b-tx as I've found but it is not working. Electrical technicians has measured the voltage, the ground, the frequencies and they say that all is OK. I'm in europe so 220 V, 0 ,50 khz (I think). I'm 100% sure that it's not a network or network cabling problem. What can I tell them, what can we do to solve this problem. Is there any other measurement that we can do (I don't know much about electric)? Thank you Erman Ulusoy
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Signal propagation? Cabling problem?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Is the electrical outlet in your room from the same source as the technician's room? Is the technician's room on the UPS? Some UPSs put out a modified square-wave instead of a sine-wave. This can cause problems with some electronic equipment. Have someone look at the voltage waveform with an oscilloscope.
Dave M. wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hello Alan, In the technicians room we've tried with the ups and the city electric with both of them we get the same problem. Today I've tried in my room and I've used my own network cable (with the technicians room electric) it's working without problem. When I change the network cable, plug it to the switch directly get the electric from the technicians room it's not working. When I plug directly to the switch and get electric from my room it's working. I really don't understand. Our electrical technicians checked the signal with an oscilloscope and they told me that it was sinusoidal. They told me that it could be a ground problem. I don't know what they'll do next. Thank you Erman Ulusoy

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Put a current probe on the cable and see what common mode noise you have.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.