EMI question for the Thermaltake Tech

[Hap]

I sent an e-mail to thermaltake about my new case, but the responds was not what I would call helpful. I have enclosed the question and responds, any thoughts.


*I recently purchase a Thermaltake Armor MX VH8000BWS and have a question about possible EMI effect on a TV connected by way of cable within about 8 feet of the case; the Thermaltake clear side panel is in the same direction as is the placement of TV and about the same height. Because of the large clear panel is it possible to allow increase EMI from the case to reach this TV. I understand that TV's are not really equipped to diminish EMI effects very well. If this is true will Thermaltake change the way the clear panel is made to incorporate a very fine mash screen grounded to the case to suppress any EMI emissions*

Responds:

Dear Customer,
Thank you for contacting Thermaltake.
We are not going have the mash screen side panel for this chassis this time.
But we have VH9000SNS with mash screen side panel.
VH9000SNS: http://www.thermaltakeusa.com/Product.aspx?C=1381&ID=1774
If you have any further question or suggestion, please feel free to contact us at anytime. We value your business and opinion.
You may also find parts, refurbished, and discontinued items athttp://www.thermaltakestore.com/
Have a great day and thank you for choosing Thermaltake.
Regards,

[Thermaltake - Michael Zhang]

It's unlikely any EMI from the computer will have effects on the TV through the side panel and as such Taiwan does not produce such a item.

[Hap]

Firstly, thanks for the responds.
Let me describe what I have viewed and how I found the computer to be related to this issue, which is understandable and I can most likely fix the error very easily if need be.
When the computer is on and I am viewing certain channels I see vertical lines that travel across the TV at different speed rates, like if a variable motor is running on the same AC circuit.
So I open the case and disconnected each of the fans one at a time until all are not working; the side panel first, CPU fan, chipset fan, front fan and then rear fan, which only leaves the power supply fan which I can’t disconnect. Only when I turn off the computer does this EMI stop.
So my best guess was that because of the large clear side panel it is possible that the system could emit EMI due to open shielding.
Don’t misunderstand me, I spent many weeks deciding which case to buy and I am not unhappy with my choice.
I just thought maybe a finer mash screen which would not prevent or take away the viewing of inside components; which is a selling factor for said case, might be in order.
As an end user my concerns is only to strengthen the value of the case/company not take away.
My professional field is in the Aerospace Industry and it has exposed me to many sorts of Electronic and Electrical effects including EMI testing.
Again, thank you for your time

[PrairieDawg]

Just thinking out loud.... Could you not try wrapping (or just covering) your clear side panel with aluminum foil to see if your theory is correct? I'd be more likely to suspect that both units are on the same electrical circut and power fluctuation is causeing the issue. Currently myself and my brother in law are using windowed cases (Antec 900s) in fairly close proximity to a television with no visible problem. I have previously run without side panels as close as two feet from a t.v. with out noticing any interference. Not saying the problem you are seeing is not what you suspect but I do doubt it.

[Thermaltake - Michael Zhang]

Are you noticing it on a CRT or LCD TV?

I've had a system within an inch of a CRT TV and can't say I have noticed any weird effects. Having a CRT monitor next to a CRT TV certainly did produce some strange discolouration effects though.

I do agree with you the perspex isn't a good EMI dampener and allows more through but unfortunately the Armor MX does not come with a solid side panel version which would be ideal in enclosing EMI.

As for the mesh side, to be more effective a finer mesh would be necessary and this IMO would detract too much from the original clean looks and I'm guessing it was not considered for the Armor MX.

PrairieDawg does have a point that the problem may be elsewhere rather than the small EMI emitted through the side window.

[Hap]

My next move was to use a sheet of aluminum foil connected to the case AC return side to clarify the issue, just haven’t done it yet. If this does prove a difference it still will not affect my use of the case, just when I will watch TV and have the computer on at the same time…It would look funny hanging a sheet of foil over the case just to keep this from happening, I just couldn’t bring myself to do that..L
After the assemble of the case I did move it back to where the older version case was along with the same setup with the ViewSonic CRT and the newer LCD next to it, I did also turn the power of to both just for a matter of course, no change. The Logitech wireless keyboard and mouse are also at the same location as before. BTW, since the wireless keyboard and mouse operate around 20 to 30 MHz I tested them as well, because TV’s will pickup interference from this frequency, but they proved to be ok.
As for the CRT place next to a TV, it certainly will produce some strange discolouration effects, due in part to the strong magnetic field produce at the tube, even tho the tubes of most CRT are shielded; better then any TV, to close is still to close, something I wouldn’t do knowing this.
As I stated before, TV’s are not designed with good shielding from outside sources.
The only course of action left if all else fails is to review the new Power Supply, since it does have a fan speed control circuit and is a high freq switcher design for the pwr output.

Hope I haven’t been to techy with this, I have tried to dummy down the language so that I can be understand.
If ya haven’t seen an EMI test before or have then ya understand how one could lose the folks just talking about it

[Hap]

missed one item you asked, The CRT and LCD are placed at the right hand side of the case, which is a full metal panel, and no problems with both running

[Hap]

There is one more thing I will try, leave the TV where it is and connect the TV to a different AC circuit in another room that I know is on a different AC phase line and see what happens, just to eliminate the feed back path of the power supply switching circuits.

[Hap]

Update, Measured continuity between Case to AC ground source at outlet; which also measures through the UPS system as well, correct reading. Enclosed clear side panel of case with a metal shielding which is grounded to the case return with not effect, even tho this really is not a good shielding practice. Without moving the TV location, plugged the TV into another outlet on a different circuit on a different floor, no effect. Using frequency monitoring equipment placed near the clear panel side of case, notice a freq of 3MHz, but rich in harmonics??? My CPU is 3MHz, the other producing generator with a high freq is the Power Supply Switching circuit, most likely running about 200 to 300 KHz.
Maybe it would be easier to just move the silly TV….