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SDI Wire issue Belden 1855A - Studio Video Hub

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Kevin Hotz
SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 7, 2011 at 11:20:40 pm

Hey Everyone. I have a small AV tape room. (2Macs/Blackmagic cards, 2PC/Skymicro cards, 2DVW-500, 2 J-30's, and 2 1800's, Studio Video Hub by BlackMagic router)

I recently had a company come in and re-wire my room using Belden 1855A SDI cable. My longest Cable run is about 30 feet.

I am getting a very light snow look in the black of my video, but only on certain ports of my blackmagic Router. The first router it was on port 3 (DVW-500). Thinking it was a router issue, I exchanged it with Blackmagic and the new router worked fine for a week. After the week passed, I have noticed the snow again, in the black, but this time its on port 7 (Mac with Blackmagic Card)

Basically what I am asking is, Has anyone else dealt with any issues with this wire? I am having the company come back in to check everything (they did the first time also) But did we just go with a bad wire? Any ideas here?

All this room currently handles is SD NTSC. Any ideas would help.


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Sam Cole
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 8, 2011 at 1:13:08 am

Get your installers to put a SDI tester on the cables and see if you are getting crc errors.

We only use double braided shield cables and the cable you mention is single braid + foil.

Sam Cole
On line Mastering Facility
FCP, Avid, Adobe
Sydney, Australia


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Jim McDonald
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 8, 2011 at 2:12:15 am

We have the ame "light snowfall" issue with a BlackMagic router with 1694a cable in all the SDI plant, originally installed on a GVG7000 router and working solidly with the GVG.


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Bob Zelin
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 9, 2011 at 2:04:44 pm

Belden 1855A is excellent cable, rated for HD-SDI installs. I just finished
XOS Digital, installing two BMD Broadcast Videohubs with 1855A.
The cable is not your problem. You need an engineer to troubleshoot your system
to see where the problem is coming from. You should have hired an engineer, not a low
voltage cable installer to build your system.

Bob Zelin



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Patrick Sproule
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 9, 2011 at 11:04:31 pm

I'd be having a close look at the connectors they have used and how well they terminated them. If it's not the router and not the cable then this would be the next port of call IMHO.

Pat


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Bob Zelin
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 10, 2011 at 12:26:00 pm

Pat is absolutely correct. If the connectors are not the correct connectors for Belden 1855A (Kings 2065-11-9), you could have poor grounding which will give you the "snow" effect".

Even worse, if the guy making the cables did not use the stripping tool correctly, and cut off the shield of the cable, or cut thru most of it, so there is not a full shield, this will have the same effect - snow.

SO, how do you actually find this problem. You take one SDI source, one SDI monitor, sit right near the router, and with two KNOWN GOOD CABLES, you test each crosspoint, one at a time. In two hours, you will know if you have a bad router, or bad cables.

Bob Zelin



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Kevin Hotz
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 10, 2011 at 5:26:28 pm

Thanks for all the Info everyone. I am having them back to get things tested again. Im beginning to doubt its the router. I am just glad there weren't any horror stories about the cable.



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Kevin Hotz
Re: SDI Wire issue Belden 1855A - Studio Video Hub
on Oct 18, 2011 at 11:04:39 pm

So this one ended up being a weird one. The connectors are the correct ones, KINGS 2065-11-9. We re-spliced and connected new connectors and the snow was still there. So we just ended up replacing the whole wire and now everything seems fine. So it looks like a glitch in the actual wire somewhere in the run.

Kevin Hotz
Director Of Operations
TJ&A


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