soundspider Posted June 1, 2017 Share Posted June 1, 2017 Hi, Quick query - just done an install of a projector and TV screen fed over VGA. Cable run from op point to projector is about 35m. There is then a powered distribution amplifier and 1m cable to projector and 5m cable to TV. The system works perfectly with one laptop, but not with the new laptop the church have just bought - the laptop doesn't recognise its been plugged into anything. The VGA output of the laptop does work with a short lead into a projector. Is this a computer issue? Too long a cable run? Its very odd that its fine with one laptop and not the other. Any suggestions what the problem could be? How to solve it? Any workaround? Thanks in advance, Alan Link to comment Share on other sites More sharing options...
boatman Posted June 1, 2017 Share Posted June 1, 2017 35m is a long cable for VGA. Try a VGA to CAT5 extender. Link to comment Share on other sites More sharing options...
timsabre Posted June 1, 2017 Share Posted June 1, 2017 Also try a short cable with the splitter still in circuit in case it is the splitter doing something to prevent detection like blocking the EDID or something. Link to comment Share on other sites More sharing options...
soundspider Posted June 1, 2017 Author Share Posted June 1, 2017 Is there a reason why it would work on one laptop and not another? Do different laptops give different signal strengths out through their VGA? And was of the impression VGA comfortably did up to 65m? Is this wrong? Never had an issue with this length of run before. Thanks, Alan Link to comment Share on other sites More sharing options...
Stuart91 Posted June 2, 2017 Share Posted June 2, 2017 VGA will fail more gradually than HDMI. The picture begins to deteriorate, ghosting appears, and detail is lost. With HDMI and other digital formats, there is a "cliff edge", the picture is fine and then when it crosses the threshold fails completely. The acceptable length for a VGA run depends on the cable used. Better quality cables will carry the signal further with less loss. Also the resolution used has a bearing too. Is there a chance that the non-working laptop is outputting a higher resolution? Link to comment Share on other sites More sharing options...
soundspider Posted June 2, 2017 Author Share Posted June 2, 2017 Its not outputting at all! Won't recognise that its plugged into a secondary monitor and won't "detect" it. Gonna try plugging straight into the projector, bypassing the splitter to see if that's causing a problem. Failing that I may have to rewire with Cat5 (although its not a straightforward cable run so trying to avoid!!). Do different laptops give a stronger/weaker signal out through their VGA sockets? Link to comment Share on other sites More sharing options...
beware Posted June 2, 2017 Share Posted June 2, 2017 Put a powered splitter at the op point. Link to comment Share on other sites More sharing options...
ninjadingle Posted June 2, 2017 Share Posted June 2, 2017 As Tim said - your problem is probably EDID detection. Have a look at this... Solution? Use the old laptop or invest in baluns, though if you're going the balun route why not use HDMI? Link to comment Share on other sites More sharing options...
soundspider Posted June 2, 2017 Author Share Posted June 2, 2017 Put a powered splitter at the op point. I had thought of trying this - likelihood of working? I have a bad feeling I'm just gonna have to bite the bullet and run cat5 because I can't see the church going for the old laptop idea. Other thing I forgot to mention was there is a composite video camera scan converted to VGA and fed to the projector and TV via a manual switch - works perfectly! Weird that some things do and some don't. Thanks for all your replies, Alan Link to comment Share on other sites More sharing options...
revbobuk Posted June 2, 2017 Share Posted June 2, 2017 Put a powered splitter at the op point. I had thought of trying this - likelihood of working? Pretty high, I would have thought. And they are dirt cheap, so well worth a try. Plus it lets you put a local monitor there, and if you are using an extended desktop, which you may well be, gives you the ability to see the output even when you have blanked the projector. I've always used this method. But it's also very true that the quality of the 35m cable is significant - you can easily run 50m with a really good cable. Link to comment Share on other sites More sharing options...
MarkA74 Posted June 2, 2017 Share Posted June 2, 2017 Is there a reason why it would work on one laptop and not another? Do different laptops give different signal strengths out through their VGA? And was of the impression VGA comfortably did up to 65m? Is this wrong? Never had an issue with this length of run before. Thanks, Alan 65m is an EXTREMELY long distance for a VGA signal to go without some sort of signal boost! It's not unfeasible for laptops to output differing signal levels from one brand to another. Have a read of this for EDID's & VGA from Extron:- LINK Link to comment Share on other sites More sharing options...
david.elsbury Posted June 2, 2017 Share Posted June 2, 2017 Yes, some laptops can be weak on the output. At a previous job, we had a conference room with a RGBHV (basically VGA) run of about 25m to a patch room and then 25m back to the projector. Our show laptops worked fine, one day the hotel GM came down to give a presentation and his laptop would not work at all :( Put an Extron 203 line driver in and all was well... Link to comment Share on other sites More sharing options...
timsabre Posted June 3, 2017 Share Posted June 3, 2017 If the laptop is not detecting the projector, this is nothing to do with a "weak" output on the laptop. This means that the laptop is not detecting the control signals which the projector sends back to give its vital statistics, this is called the EDID. Do the old and new laptops have the same version of windows on them? Windows is getting more and more fussy about edid... Link to comment Share on other sites More sharing options...
soundspider Posted June 3, 2017 Author Share Posted June 3, 2017 No, Tim, they don't. I think the one that works is Windows 7 and the new one is 10. Does that mean adding an amplifier will or won't work? Link to comment Share on other sites More sharing options...
Dave m Posted June 3, 2017 Share Posted June 3, 2017 Try plugging a different projector or a monitor into the projector end and see what's happeningAlso look at the second screen output settings on the pc Link to comment Share on other sites More sharing options...
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