Lcd Hdtv Interference

[jezchesters]

Can anybody help, as this problem is driving me crazy!!

I bought a Samsung LCD Hi-Def TV at the weekend, as I have a lot of Hi-Def TV programmes recorded on Hard Disk. I got a VGA lead to rig my laptop up to the TV for playback. Now the problem I have is that whenever my laptop is plugged into the mains, I get visual interference - a kind of wavy, snowy effect.

I presume that the interference must be coming from the mains, as the interferece stops the moment I run my computer off battery power. I went out and bought a UPS to regulate the voltage on both the TV and laptop power supply, but the intereference persists. I have even run an extension cable from a different room to power the laptop, but still no luck.

I would appreciate any suggestions whatsoever, as if I can't use my laptop, there is little point in having bought an HDTV as True does not broadcast in Hi-Def...

Help!!!

[opalhort]

What happens if you plug both, HDTV and laptop into an outlet of the UPS?

Have you tried to run both TV and laptop off the UPS with the mains to the UPS unplugged?

opalhort

[Crossy]

What happens if you plug both, HDTV and laptop into an outlet of the UPS?

Have you tried to run both TV and laptop off the UPS with the mains to the UPS unplugged?

I'm thinking along the same lines, grounding issue maybe. Certainly try the TV on the UPS with and witthout the mains.

Report your results here for further interpretation

[jezchesters]

Thanks guys!

I tried with both the HDTV and the laptop plugged into the UPS last night and still no joy. I'll try it again later without the UPS plugged in and post the results...

Thanks again!

[Tywais]

What happens if you plug both, HDTV and laptop into an outlet of the UPS?

Have you tried to run both TV and laptop off the UPS with the mains to the UPS unplugged?

I'm thinking along the same lines, grounding issue maybe. Certainly try the TV on the UPS with and witthout the mains.

If running off the UPS (unplugged from mains) it is still showing the interference then it may be the power supply brick of the notebook itself. These are switch mode power supply devices that can be running up to 200-300 kHz switching speeds. A poorly built/designed one can produce a significant amount of EMI (electromagnetic interference). Also, the VGA cable you are using, does it have a large cylindrical item near one end? This is a emi/rfi suppressor and without it it may be more susceptible to noise from the brick or even generate more noise itself.

[jezchesters]

Hi Guys!

OK - tried it with the UPS unplugged - it's even worse! In fact, the best picture I can get by not even using the UPS! This is driving me crazy...

I'm using bog standard power supply and VGA cable - does anyone have any more suggestions?

Thanks!!!

[solo siam]

Better VGA cable.

Try plugging in the laptop to a power point away from the TV.

Also may have something to do with the refresh rate/resolution, make sure you are using 1366x768 resolution (or whatever the TV is).

[sumrit]

What happens if you plug both, HDTV and laptop into an outlet of the UPS?

Have you tried to run both TV and laptop off the UPS with the mains to the UPS unplugged?

I'm thinking along the same lines, grounding issue maybe. Certainly try the TV on the UPS with and witthout the mains.

If running off the UPS (unplugged from mains) it is still showing the interference then it may be the power supply brick of the notebook itself. These are switch mode power supply devices that can be running up to 200-300 kHz switching speeds. A poorly built/designed one can produce a significant amount of EMI (electromagnetic interference). Also, the VGA cable you are using, does it have a large cylindrical item near one end? This is a emi/rfi suppressor and without it it may be more susceptible to noise from the brick or even generate more noise itself.

Sounds like this is your problem. Are all the leads within the VGA cable indivdually screened and earthed? If not thats what you will probably have to get. Philips TV's used to suffer from a similar problem, with both VGA and scart leads that were not individually screened.

[jezchesters]

Thanks again guys!

Ben, I've tried plugging the laptop in 2 rooms away but still have problems. I've tried moving the Power Supply 'Brick' closer then further away from the VGA Cable but doesn't seem to make any difference. I'll try to get hold of a screened one - does anyone have any recommendations on where to get a top-notch VGA cable in Bangkok?

Thanks!

[jezchesters]

Sorry to bump this up...

Does anyone know where I could get a good quality, ferrite shielded VGA cable from in Bangkok?

Thanks!!!

[sumrit]

Sorry to bump this up...

Does anyone know where I could get a good quality, ferrite shielded VGA cable from in Bangkok?

Thanks!!!

Don't know where you can get leads from but the ones we had to use to prevent the problems on Philips TV's were leads where each individual wire within the cable were screened and earthed. Ferite shielding on its own didn't cure the problem. I can't remember how much VGA leads were but scart leads were about £20 each from CPC in the UK.

Edited July 9, 2007 by sumrit

[Firefoxx]

I use a bog-standard VGA cable (but with ferrite ring) to run 1920x1080i on my Benq LCDTV with zero interference from an Acer notebook. Have also tried the HDMI port on a Benq notebook with DVI adapter and bog standard DVI cable, also no problems. If it's really the switching power supply (the brick) that's the problem, then you could probably buy/try another one and see if it solves the problem. They're not that expensive, less than 1,000 baht.

[jezchesters]

I was thinking about replacing the brick, but I also get interference when my external hard-drive is running. I'm thinking that if my VGA cable isn't shielded, then it will pick up interference from most things.

Went to Panthip last night to pick up a shielded cable, but when I got it home realised I'd been an eejit and bought a male/female version...

Try again later!

[jezchesters]

I was thinking about replacing the brick, but I also get interference when my external hard-drive is running. I'm thinking that if my VGA cable isn't shielded, then it will pick up interference from most things.

Went to Panthip last night to pick up a shielded cable, but when I got it home realised I'd been an eejit and bought a male/female version...

Try again later!

Cheers guys - finally got it sorted!

Bought a shielded VGA cable and it works a treat - fantastic quality!

Thanks again!

Jez

[Tywais]

Cheers guys - finally got it sorted!

Bought a shielded VGA cable and it works a treat - fantastic quality!

Thanks again!

Jez

Glad to hear it! Noise/interference problems can sometimes be a bear to locate.