PC DVI --> Sony VPL-VW50 HDMI problem

Discussion in 'Projectors, Screens & Video Processors' started by ukaudiophile, May 6, 2007.

  1. ukaudiophile

    ukaudiophile
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    Hello,

    I'm hoping someone here can shed some light on a rather strange problem I've encountered in my home theater system.

    My main source for my VPL-VW50 is my trusty HTPC which uses an ATI 9250 graphics card with the latest Catalyst drivers and control centre with Windows XP SP2. This is connected to the VPL-VW50 via the DVI output port, I have a DVI-HDMI adaptor and from there I run a high quality HDMI cable from the PC to the projector. My problem is that I sometimes cannot get a screen on the HDMI input. I have tried starting the projector up first, then the PC, vice versa, trying starting them up almost simultaneously etc and for some reason the projector will sometimes refuse to display the PC output. The connectors are solid and they are untouched, as the home theater is in it's own dedicated room. I really cannot figure out why this happens. I know HDMI has a set of handshaking protocols, but surely these can be initiated whenever it detects an input, not at a specific moment at startup.

    I have a suspicion that the problem could be something to do with the ATI card trying to autodetec the display, and if it cannot auto detect it simply drops back to the VGA analogue output and effectively 'gives up' trying to output through the DVI port. If this is the case, is there a way of forcing the card to only output through the DVI port at a pre determined resolution?

    If I cannot get this to work reliably, I will probably resort to a newer graphics card with twin DVI outputs to ensure the card has to output digitally to my projector, but I want to avoid that if possible as this machine is still only AGP X8 and I suspect if I want a silent, twin DVI output graphics card I'll probably need to go for a PCI-Express board, and whilst I plan on doing this anyway later this year, I'd really like to hang on a few months before committing to this upgrade.

    If anyone out there has had a similar experience, or can shed any light on the problem, it would be greatly appreciated.

    Thanks and best wishes,

    Dave
     
  2. ukaudiophile

    ukaudiophile
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    Hello,

    I finally managed to figure this problem out earlier this week, and wanted to leave the answer here should anyone else run into similar HDMI related problems.

    I wish I could say it was some devious little registry hack, or a problem buried in the service menus of the VPL-VW50, but I'm sorry to say it was a mix of waaaay too much caffeine stopping me thinking straight, and a failed HDMI cable. To briefly recap, the PC running a Radeon 9250 graphics card had been giving me some problems for a few months with sycheonisation with the projector, the main problem being that no HDMI signal would be displayed by the projector. I thought it was a HDMI handshaking problem, or that it may be related to HDCP, but as it did this with the desktop along with DVD playback, I ruled that out pretty quickly. It turned out to be the type of connection I was using. I use a DVI --> HDMI adaptor on the back of the PC, then run a HDMI --> HDMI cable from the PC to projector, the HDMI cable was so stiff at the connector end, and the space between the back of the PC and the wall so tight, that the sharp angle had broken the HDMI cable and was causing an intermittent connection.

    Now a broken lead is one thing, but what has worried me is that I have another PC on a 720p back projection TV using a DVI --> HDMI connetion, and that is tight on space also, but that cable hasn't given me a moments trouble. The cable seems much more flexible than the HDMI, and frankly the ability to lock the DVI connector in with screws is very reassuring, I simply don't think HDMI cables are that robust, certainly when compared with an industrial connector like DVI. The moral of this story is to check your connection thoroughly, and if you're using a scheme like mine, don't use adaptors, use an actual DVI --> HDMI cable in the first place.

    I have now invested in not only a new DVI-HDMI cable, but also a second cable of the same type and had the HDMI - HDMI lead replaced, so at least I can now quickly substitute cables in the event of a suspected cable failure in the future.

    I hope this helps someone and prevents the hours of frantic bug hunting I undertook.

    Best wishes,

    Dave
     

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