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BNC Connection

Last response: in Computer Peripherals
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Anonymous
a b C Monitor
June 14, 2001 4:24:42 AM

I'm looking at two similar monitors, trying to decide which one is better. One, iiYama i90A, has BNC connection. The other one, iiYama VisionMaster Pro451, doesn't have BNC connection, but it has somewhat better refresh rates (for example, it has 92 Hz versus 85 Hz at 1600x1200, 107 Hz versus 98 Hz at 1280x1024, and 140 Hz versus 130 Hz at 1024x768).

So my question is: Just how much difference does a 5-jack BNC connection make versus normal monitor connection? Is there a marked difference in quality? After all, each color is sent separately, allowing to maintain the strongest signal from the source. Or is refresh rate more important?

Leo

More about : bnc connection

June 14, 2001 8:45:39 PM

BNC connectors are a legacy feature from the days before the DB=15 connector became widely accepted as the VGA standard. Most DB-15 cables use the same 75 Ohm coaxial cable as the BCN cables.

With any connector (BNC or DB-15) there is a possibility of an impedance miss match that could send ripples up and down the video cable. The ripples can be amplified by the video amp and show as shadows or ghosts after light to dark or dark to light transitions on the screen.

Most manufacturers are taking the connectors (BNC and DB-15) off the monitor all together and permanently attaching the cable to the monitor. By doing this they can solder the cable wires directly to the video amplifier board inside the monitor, effectively eliminating any chance of impedance miss match on the monitor end from a connector. An added benefit to a permanently attached cable is, you will never loose it, should you move your system. In any scheme there are trade off. The trade off in permanently attaching the cable is that if the cable should go bad, you need to send the entire unit in for service. My experience says that occasionally cables do break, but the failure rate of cables is very low.

Remember the side that connects to the video card is still the 15-pin d-sub. Someone much wiser that I said, "it doesn't make sense to anchor a bridge with concrete on one side and tree vines on the other". If both sides have BNC (or soldered) there may be an improvement at the highest resolutions and refresh rates only.

Jim Witkowski
Chief Hardware Engineer
Cornerstone / Monitorsdirect.com


Jim at http://www.monitorsdirect.com
June 15, 2001 12:02:14 AM

I agree, there is nothing to gain with BNC connections on the monitor when the video card output is D-Sub.

Soldered cables are not so good in my opinion though, having spent a fair few hours fixing bent pins on a permanently attached cable.

Not an image quality issue though.
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June 16, 2001 6:22:28 PM

there is no point in the 5 jack sh!t... all the colours are sent seperately anyway with the 15 pin standard connection 5 jacks allows for 10 contacts 15 pins allows for 15

you do not strengthen the weak by weakening the strong
Anonymous
a b C Monitor
June 17, 2001 2:05:46 AM

I don't understand... All the monitor reviews say that a BNC connection is a sign of a high-end monitor aimed at imaging professionals. OK, I've got it from the other responses that it probably would make only a little difference. But now you're saying BNC is actually worse?!

Leo
June 17, 2001 8:06:27 AM

exacyl my point... 5 jacks with 2 contacts each...

you do not strengthen the weak by weakening the strong
!