VGA/USB KVM Question with HSYNC/VSYNC Voltage Issues - AVS Forum
CRT Projectors > VGA/USB KVM Question with HSYNC/VSYNC Voltage Issues
thebozak's Avatar thebozak 08:04 AM 01-06-2009
I have an installation for an industrial facility in which I am having some issues. This question is technically a cabling question, but I figured it could easily fall in this realm of expertise.

This is essentially a two part problem.

Problem 1:

I have purchased an industrial brick pc with an on-board video card. When connected to a custom touchscreen, I found that the monitor would not sync up with the pc. After a bit of runaround, I found out that the the VGA connection at the monitor is expecting a voltage range of 3.3VDC to 5.1VDC at the HSYNC/VSYNC pins (this is higher than most desktop monitors I believe). My industrial pc chipset only supplies 2.5VDC at those pins (this seems to be lower than my laptop and home pc as tested).

Replacing the video card is not an option given the prefab casing on the pc. I have considered purchasing another industrial pc from another manufacturer with an adequate output voltage to sync up to the monitor. I am hoping to find a solution to solve this problem in conjunction with Problem 2 (read on).

Problem 2:

The touchscreen monitor will be separated from the PC by approximately 20-25 meters of cabling (1 VGA and 1 USB). I would use a simple KVM extender, except that most of the products I have seen require power on the receiver end (5-12 VDC). This is a problem because the touchscreen monitor is located in a hazardous rated area (read: explosive gas, so it needs an industrial hazard rating - if not rating, the device cannot be powered in the hazardous area).

To solve both of these, I would need some sort of good cable extender, VGA and USB, which is self powered, and has the possibility of amplifying the VGA voltage signals. I am open to a multiple part solution as I doubt there is something clean out of the box to solve this problem.

Thanks in advance.
Brian

Tim in Phoenix's Avatar Tim in Phoenix 11:28 AM 01-06-2009
Hello

Interesting situation. Your problem may be worse than you realize. VGA graphics cards were never meant to drive 60-70 feet of cable; 6 feet is more typical. Also, "touchscreen" implies signals from the monitor back to the graphics card, and I have not heard of that as a feature on most kvm extenders. Try these guys http://www.covid.com/ If a solution is out there, they are probably aware of it.

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thebozak's Avatar thebozak 12:43 PM 01-06-2009
The touchscreen communicates over USB, which I have seen extender cables for.

I was actually looking into a vga extension cable from a quality company like Black Box. They have a number of VGA extension cables (anywhere from 50' to 150') in length. I think the actual cable does a conversion from VGA 15pin to coax/twisted pair then back to VGA 15pin at the end. Kind of interesting.

This still would not solve the voltage level issue, though.

At any rate, thanks for your help. I'll check out that website.
bomrat's Avatar bomrat 06:21 PM 01-06-2009
GEFEN VGA COMPONENT VIDEO EXTENDER UPTO 330' VGA-141LR

should work just fine
Tim in Phoenix's Avatar Tim in Phoenix 06:38 PM 01-06-2009
Hello

Some of the Extron FGA interfaces, a 202xi for example, will punch up the video, not sure about sync; you would need five coax runs funneled back to an HD15 connector at the monitor. Let me scope one for sync amplitude.
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Tim in Phoenix's Avatar Tim in Phoenix 10:56 AM 01-07-2009
Hello

I can probably solve the video/sync side of your situation but I need to hear from you.

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thebozak's Avatar thebozak 12:09 PM 01-07-2009
Tim-

I am familiar with some of Extron's product line.

I am interested to hear your ideas on how I can boost the sync voltage. I apologize for the late reply.

Thanks,
Brian
Tim in Phoenix's Avatar Tim in Phoenix 12:49 PM 01-07-2009
Quote:
Originally Posted by thebozak View Post

Tim-

I am familiar with some of Extron's product line.

I am interested to hear your ideas on how I can boost the sync voltage. I apologize for the late reply.

Thanks,
Brian

Hello

I propose to test and offer you an Extron device (pc end only, no power needed at monitor) and a continuous Canare five channel cable bundle with bnc connectors both ends, and an adapter back to a vga plug for the monitor. PM or e.mail me with your e.mail and phone.

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