DVI to HDMI 15m cable problems!!!

[k12nky]

Didn't know where exactly to post this questions so i apologise if it's in the wrong place.

If someone can shed any light on this problem i think i will marry them because i am at my witts end!

I have a Philips 42PF5421 42" LCD TV and i am hooking it up to my pc to use as a media centre pc. I had my pc working no problem through the tele using a 1m dvi to hdmi cable earlier this year and was running at full 1080p resolution...stay with me...I know want to move the pc upstairs out of the way and have purchased a 15m hdmi to hdmi cable and a dvi to hdmi converter so that i can run the cable upstairs too....my problems begin!

With the new cable connected i cannot get the tv to run at anything higher than 800x600 resolution? obvisouly the cable faulty then you say, took the cable to a friends house and connected it up and hey presto no problems at all!....he uses a hdmi out graphics card so only thing different is adapter....adapter faulty then? wrong....came home and used a 1m hdmi to hdmi cable using the adapter and works perfectly!! keep reading please....

So what is causing my problems? signal loss on the 15m cable? why did it work at my mates house then? ATI 9800pro not working properly? why does it work fine with a dvi to hdmi cable then? drivers? loaded the latest cataylst and no change?

what on gods earth could be wrong??? i am desperate for any help you can suggest.....i tried powerstrip too and still nothing....if i set resolution to anything higher than 800x600 screen flickers and becomes unstable...

Oh tried a 32mb matrox card and did see a slight improvement but still not stable enough....strange!!! on boot up i get pink screen with black artifacts!!!


HELP HELP HELP HELP

 

[cybrey]

Is the cable a cheap one ?

HDMI ( I'm not sure about DVI) uses handshaking which has varying degrees of sucess between devices, which would explain why your seeing results on your friends machine. Its particularly susceptible to not working over longer distances anything over 5m.

I would suggest buying a more well known branded cable ( if you haven't already) such as QED but buy from a reputable shop that will give you refund if the cable doesn't live up to its job.

 

[stevelup]

There are at least two more variables in this connection:-

The quality of the LVDS driver in the video card
The quality of the LVDS receivers in the display

Have you tried taking your PC round to your mates house and using your cable on his display. If it works, the issue is with your display...

Conversely, is it possible to bring your mate's PC round and hook it up to your display. If it works, the issue is with your graphics card.

What refresh rate are you attempting just out of interest? Where did the 15M cable and the DVI-HDMI adapter come from?

Steve

 

[Joe Fernand]

Hello k12nky

Lots of possible problems!!!

HDMI/DVI Transmitter and Receiver chips differ in their ability to send/receive signals over long cable runs.

The DVI Transmitter in your PC or the HDMI Receiver in your Display may be less able to cope with the signal drop over 15m than the Transmitter/Receiver in your mates system.

The 15m HDMI cable may be introducing just enough signal drop to cause a problem in your system but not in another system with a more tolerant Receiver in the Display.

You could try an HDMI Repeater (http://www.octavainc.com/HDMI extender.htm) or a different HDMI cable (http://www.bettercables.com/index.asp?PageAction=VIEWPROD&ProdID=134).

A different Graphics card may work - though if the problem is in the Display its unlikely to solve the problem.

Joe

PS A pink screen on start up is not that unusual with a long DVI/HDMI signal run to a 'TV'.

 

[k12nky]

There are at least two more variables in this connection:-

The quality of the LVDS driver in the video card
The quality of the LVDS receivers in the display

Have you tried taking your PC round to your mates house and using your cable on his display. If it works, the issue is with your display...

Conversely, is it possible to bring your mate's PC round and hook it up to your display. If it works, the issue is with your graphics card.

What refresh rate are you attempting just out of interest? Where did the 15M cable and the DVI-HDMI adapter come from?

Steve

Thanks for the reply, i have tried multiple refresh rates but it is currently on 60hz. The cable isn't the most expensive but my mate has just bought one and its 20m and his works fine as does mine on his setup!! i doubt very much it could be my display as it works with my shorter cable absolutely fine and has done for some time...

Anything else i can try? could it be anything to do with my 9800pro?

 

[Chris Muriel]

[email protected] good to see that the answers here are in agreement with what I just wrote at http://www.avforums.com/forums/showthread.php?t=614394


Chris Muriel, Manchester

 

[k12nky]

Hello k12nky

Lots of possible problems!!!

HDMI/DVI Transmitter and Receiver chips differ in their ability to send/receive signals over long cable runs.

The DVI Transmitter in your PC or the HDMI Receiver in your Display may be less able to cope with the signal drop over 15m than the Transmitter/Receiver in your mates system.

The 15m HDMI cable may be introducing just enough signal drop to cause a problem in your system but not in another system with a more tolerant Receiver in the Display.

You could try an HDMI Repeater (http://www.octavainc.com/HDMI extender.htm) or a different HDMI cable (http://www.bettercables.com/index.asp?PageAction=VIEWPROD&ProdID=134).

A different Graphics card may work - though if the problem is in the Display its unlikely to solve the problem.

Joe

PS A pink screen on start up is not that unusual with a long DVI/HDMI signal run to a 'TV'.

Thanks for your help and it does give me food for thought....i will try taking my pc to my friends house and hooking it up and see what i get...i would hate to think it was my tele as its almost brand new and over a £1000!! that would really suck....

My pc is quite old now and im using a 9800pro on agp...my friends is a pci-express...do you think it could be anything to do with that? would u suggest trying a different card in my system?

 

[stevelup]

i doubt very much it could be my display as it works with my shorter cable absolutely fine and has done for some time...

That's meaningless I'm afraid - the difference in signal quality at the end of an inexpensive 15M cable will be considerably different to that at the end of a 1M one.

If the receiver in the display isn't great, it can work fine with the 1M cable and fail miserably at 15M.

I'm pretty confident though that using a better cable or a repeater will solve your problem as your display is clearly capable of sucessfully displaying the signal.

Steve

 

[Joe Fernand]

Hello all

I guess we were all typing at about the same time - though stevelup is obviously a bit faster than the rest of us

Spent many an hour visiting Dealers premises with a whole rats nest of HDMI Cable/Switch, Distribution, Extender Gear trying to find the magic combination for certain systems!!!

Joe

PS Agreed with stevelup - if you can borrow an Extender plus a better quality HDMI cable you will likely find either option will resolve your problem.

 

[stevelup]

Random luck plays a part as well - the cost of the cable is not always reflected in it's performance.

I bought some crappy 20M cables from CPC (the cheapest ones they did) and they are faultless.

I helped out someone who was having problems with a moderately expensive 40ft (circa 12M) Geffen cable. No computers involved here - a simple connection between DVD player and Sanyo Z4 projector. The Geffen cable - which incidentally is a well regarded product - was occasionally failing HDCP handshakes and the display had 'sparklies' all over it. The cable had been swapped once already without making any significant change. I stuck in one of my cheap CPC ones (at nearly twice the length) and it worked perfectly.

Now I don't know whether the DVD player was dodgy, or the projector - because I doubt there was anything fundamentally wrong with the Geffen cables - but the cheaper cable worked better.

Pick the bones out of that if you can...

Steve

 

[stevelup]

I have got a theory - unproven - on why cheaper cables can occasionally be better...

I think that the more poorly screened cables potentially have a lower capacitance than the better constructed ones. They will pick up more noise than the better cables, but this noise is then rejected due to the differential receiver at the other end. The capacitance - however - reduces the available bandwidth slightly on the better cable.

Might well be nonsense, but it's only a theory... It's the same reason cheap unshielded CAT5 cable works better when using baluns.

Steve