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Thread: DVI-HDMI adapters, I'm tired of your sh*t

  1. #1
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    Default DVI-HDMI adapters, I'm tired of your sh*t

    it was the matrox for some reason, works good with others
    Last edited by ghosttrain; 04-24-2016 at 05:41.

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    It does sound like the adapters may just not be of quality. Now.. you said the DVI adapters work fine with a shorter length of HDMI cable but not 25'? That would be my guess as well. I deal with adapters all time and sometimes I've had some really bizarre results.
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    You may need a DVI to HDMI 'powered' sender for that length od HDMI cable.
    The 3htg may not be able to pump enough electricery down the tiny wires in HDMI.
    Have you tried using it one line at a time? Ie, with just one projector?
    Matrox stuff is usually rock solid, so
    If in doubt... Give it a clout?

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    If I remember correctly, the HDMI to DVI connectors come in 2 flavours - single link and dual link. Dual link have more connections and they allow more data rate by using extra cabling and "doubling it". It could be the DVI connectors are single and unable to handle the amount of data being sent from the HDMI output you have.

    Might be worth checking the type of adapter and also that a dual DVI adapter will fit the socket on the projectors if you're going to try one.

    Also be aware, DVI adapters don't transmit audio in event as there's not enough pins.

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    Connectors and cables matter, and there is a lot of junk out there. Thirty foot is about the limit for well constructed passive cable, anyways. Greater then 30 foot and I'm personally looking for a active cable solution. There are power injection boxes for this problem as well.
    +
    If your adapter did not come from Inland or QVS and did not cost at least 20$ a piece, you'll probably get burned.
    +
    Around work, where we have ~ 10,000 computers, we use QVS or Inland or Better. Belkin is OK, but expensive.
    Students often buy the Ebay or Best Buy adapters and get burned.
    +
    The CPU techs frequently show me cheaper adapter connectors where the plastic is discolored or melted from the current passing on the large blades. A bad connector will show up as a loss to the signal, even on a short cable run.
    +
    If I need to go any distance, I cannot speak highly enough of the FSR optical fiber based hybrid cables. I have a few installed for 75' runs at my church, and they are the cat's meow. Expect sticker shock...
    +
    http://www.fsrinc.com/innerHTML/dr-pcb-hxxm.html
    +
    FSR's cables would need sheathed in something like split loop for field work, and have a minimum bend radius of ~1.5 inch. However the peace of mind is worth it.
    +

    Take a look at Microcenter and Parts Express web sites for some mid level HDMI parts, or the big vendors like B&H Photo...

    Steve
    Last edited by mixedgas; 12-10-2015 at 07:50.
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    I use HDMI baluns my self for a long run, they take the HDMI and pass it on a cat 5 cable and then back to HDMI
    I have found that some equipment will not work with even a 25 foot cable, I believe it's due to loss of signal over the length of the cable and learned to use good quality cable and not go with cheap junk, one of the things i used to carry with me in the field was a mid quality 25 foot HDMI cable that had come from an older Mitsubishi lcd tv when the tuner and screen used to be separate parts. some TV's would not work with a customers cable and used mine to rule out the TV or the source as the fault
    You may need an amp or try using cables that have less loss, ones rated for for the higher data rates tend to work better over longer lengths.
    one customer of mine had HDMI runs over 75 feet and they had to use an amp for there installation. HDMI distribution amps in my experience where not cheap though
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

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    For your question about the dual link pins - the reason that the 'extra' pins are not wired is that HDMI does not support dual link, it is fundamentally limited to single-link (it physically does not have enough pins). In order to run resolutions greater than 1920x1080 @ 60hz (the maximum for single-link DVI) you will need some sort of active adapter that takes dual-link DVI and re-encodes it to something like HDMI V1.3 (or greater), but as far as I know this does not exist. The good news is that is all a moot point unless you are actually trying to run your projectors at higher than 1920x1080 @ 60hz, since you do not need the extra bandwidth provided by dual-link.

    As to the issue with the combination of longer wire + adapter not working, this sounds like a signal integrity issue. I have never had to deal with extra long video runs so I cannot speak from experience, but I would suspect that it is a combination of the Matrox unit being at the edge of the DVI spec in terms of minimum voltages/crosstalk/etc and the long wire + adapter is causing the signal to degrade to the point of being unrecoverable. As has been mentioned by others the solution to this is to find a higher quality cable, or ideally an active cable. Based on my experience with other (non-video) rf-related things I personally would not expect the adapter is actually causing the problem (since there is so little to screw up it it, there is just a few millimeters of wire and 2 connectors) but rather the cable (since high-quality rf cable is actually incredible expensive, so many manufactures will cheat and use an underperforming wire to make a cable which doesn't meet the official specs but works for enough people that they can get away with it).

    You also might be able to make it work by lowering the data rate to the projects, by either reducing the resolution or frame rate. Ideally you will want both of these set to the native resolution of the projector, but if it means that you have some video instead of nothing then running at 30fps vs 60 probably won't make any difference in your installation, but will halve the data rate through your wires and give you a lot higher chance of getting an almost-in-spec wire to work.

  8. #8
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    I always use Matrox for my work. And I have no problems with it. Maybe you need to buy something like that - http://www.kramerelectronics.com/pro...el.asp?pid=766 for for short range ог http://www.kramerelectronics.com/pro...8&pname=PT-571 for long range.

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    Quote Originally Posted by ghosttrain View Post
    I'm not sure what to make from these tests but all I know is if the cable or Matrox device were (only) to blame they wouldn't work properly with any display device.

    I understand why the pins were not soldered in the DVI-HDMI adapters now but from the above tests it was still the only adapter which guaranteed zero output. I don't know why, maybe the 3-4 strands of copper that were soldered to the pins was not enough or the lack of shielding on the adapter itself was to blame, but the fact is with them and the shortest HDMI cable there was no signal, but with a 1.5 meter long DVI to HDMI cable there was.
    I'm not aware of the full standards for DVI, but in that case, could it be that some cables have a twisted pair like with ethernet? Never heard of it but it might explain why one cable works and the others don't. Either that, or you must have some dud cables.

    Either way, the idea of getting a quality cable sounds like a very good place to start as only by eliminating the cabling can you then identify the adapters as the issue.

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