Can wireless networks interfere with CRT monitors

4

4fingers

Guest
I have a Relisys TE770 17" CRT monitor that is around 3 years old.
Last weekend I saw what appeared to be some kind of interference with the image going further up the screen.

Although this theory was put on hold when I saw that my graphics card fan had stopped spinning. I was able to do a botch job by placing an old CPU fan next to the graphics card to keep it cool. Even though the fan was powerful and the card never got hot the results were temperamental. It wasn't until I tried my old graphics card that I found I was still getting the same problems.

I then decided to try both card when connected to my TV and there was no problem with the display.

I have kept my old graphics card in my computer until I get a new fan but the monitor still get interference. I can temporally fix the problem by unplugging it for a while but the problem does eventually come back.

The funny thing is that there seem to be nothing in my room that has changed that could be causing the interference. I do have two speakers near the monitor but they are small and they have been there since I have had the monitor. The only thing that I can think of is that our neighbours downstairs have just got wireless broadband.

Could the wireless network be interfering or is the monitor just getting old and needing replaced.

Thank you for your time,
Graeme
 

noshoulders

Active Member
i've never heard of wireless signals interfering with monitors signals. I expect it's just getting old and needs replacing. People can't give CRT's away at the moment, i doubt you'll have trouble getting a replacement.
 
4

4fingers

Guest
I have never heard of it before either, I was just wondering if it is possible? My last CRT monitor lasted me more than 3 years and if it can still work in a different environment then I might try to sell it or give it to charity.
Here is what Windows help has to say on monitor interference:
Troubleshoot monitor and video card problems
Interference can be caused by devices that transmit radio frequencies (RF) (such as a baby monitor or CB radio), or devices that produce magnetic fields (such as a motor in an electric fan), or even by just having a tangle of power cables on or near the monitor.

Radio signals can interfere with the signal going between your computer and monitor, and in some cases can cause horizontal lines to appear, as well as other interference. To reduce interference, move the RF device away from the computer, or move the computer and monitor away from the device.

Moving magnetic fields (such as from an electric motor) can cause flickering when near a CRT screen. A static magnetic field, such as from your computer's speakers, can cause color shifts or incorrect colors in the area near the magnet.

It says that radio frequencies found in baby monitors can interfere and according to wikipedia.org the 802.11g shares the already crowed 2.4GHz range which include things like baby monitors.
IEEE 802.11
Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, baby monitors and cordless telephones.

I presume that when the screen starts to squish vertically to the top and then end up with just a rainbow haze then its a sign of interference.

Anyway I will try and move my monitor to a my friends house where there should be less interference and see what happens there, otherwise in the meantime is there anything I can do to possibly reduce radio frequency interference since all magnets and cables are far away as possible.

Thanks again,
Graeme
 

JayCee

Distinguished Member
I presume that when the screen starts to squish vertically to the top and then end up with just a rainbow haze then its a sign of interference.

A pound to a penny you have a fault on your monitor.
Can you post a pic of the symptoms?
I doubt very much the wireless network is the source of the problem.
 

Stephen Neal

Distinguished Member
Haven't heard of Wifi causing problems - but have seen mobile phones interfere with cheap CRT monitor line-scans, causing the picture to wobble left/right.

Also if you have two monitors next to each other, locked at different frequencies, or two TVs, one tuned to a channel and the other not, then the line-scans can interfere with each other giving a wobbly picture.
 
4

4fingers

Guest
Can you post a pic of the symptoms?
I can do one better and give you a video of what is happening.
My monitor Problems
Also if you have two monitors next to each other, locked at different frequencies, or two TVs, one tuned to a channel and the other not, then the line-scans can interfere with each other giving a wobbly picture.
No I do not have any other monitor next to it, and I am certain that the environment round the monitor has not changed drastically for the last few months now.
 

JayCee

Distinguished Member
The fault is in your monitor and has nothing to do with external interference.
It looks as though there is a fault in the frame scan circuit.
It could be caused by a faulty frame output IC but to be sure you would need to get it looked at by an experienced engineer.
 

Chris Muriel

Distinguished Member
Interesting use of YouTube.
The video clearly shows frame scan/sync issues.
Nothing to do with "interference" at all.

Chris Muriel, Manchester
 
4

4fingers

Guest
Thank you for both your replies.
This just goes to show how much I dont know about monitors, at the moment I will just invest in a new TFT monitor rather than try to fix this thing.

Thanks again for your time ad technical know how.
 

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