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Blackmagic SDI to Analog downconverter power


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#1 Tommy Stork

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Posted 23 February 2012 - 01:12 AM

Hi dudes, I made a D-tap power cable for a Blackmagic downconverter that I'm using for a backup. The Blackmagic unit shows +5V printed on the housing but when I plug the D-tap in with a fresh battery (Dionic 90) on the camera (15.8V) the unit's power light doesn't come on. After a friend suggested using a nearly dead battery. I did this (only two bars showing; 14.2V) the power light came on and the unit was operational. Obviously it has an operating voltage range. Anyone hear of a good (small) inline "voltage dropper?" or another idea?

Thanks,
Tommy
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#2 Osvaldo Silvera SOC

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Posted 23 February 2012 - 02:07 AM

Terry West should be able to make one of these right away for you.
How does the Black Magic downconverter work? I need to get something cause the repair on my Decimator is now a month in waiting.
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#3 Charles Papert

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Posted 23 February 2012 - 04:12 AM

Most of the Blackmagic mini-convertors have a maximum input of 12v. That's actual 12v, not 14.4, not 18. They will do exactly as Tommy noted when delivered typical 14.4 battery voltage; stop working until the voltage approaches 12v.

Those of us who spent the last couple of years dealing with the Blackmagic HDMI to SDI convertor for DSLR's are more than familiar with this issue. Intil some aftermarket solutions became available, we all had to dick around with custom cable assemblies with an inline regulator--the cheap kind tended to heat up enough to scorch the fingers. Matt Petrovsky did a fantastic job for me mounting a switching regulator inside the box (and swapping out the crappy push on power connector with a 6 pin HRS) but I wouldn't chase after him to do the same...!

If you want to order something off the shelf, here it is:

http://www.switronix...&category_id=39

Blackmagic is now making a heavy duty line of their mini convertors, and the SDI to Analog (downconverter) model is one of these. Some of them will take up to 31v, sadly the downconverter is not amongst them.

I've owned a few Blackmagic boxes and while they get the job done, they are not the most rugged (again, the heavy duty versions should fare better) or well-built, and they are prone to failure. And I wouldn't expect any better service on them vs Decimator, for those that have had issues with this.
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#4 Alan Rencher

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Posted 23 February 2012 - 12:40 PM

That's interesting. My Blackmagic HDMI - HD-SDI Mini Converter runs at 12-31Vdc. I wonder why the downconverter only runs at 12Vdc? You would think that they would have some continuity between their "Mini" series. http://www.blackmagi...ters/techspecs/
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#5 Tommy Stork

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Posted 24 February 2012 - 01:05 AM

The Blackmagic is my backup down converter so I'm not too worried about how durable it is, although it is discouraging to read about the problems with their other products . Charles, thanks for the link and the info. Boy that sucker from Switronix is nasty! I'll probably put something together this weekend and see if I can keep it smaller, (never thought I'd say that.)
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#6 Tommy Stork

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Posted 24 February 2012 - 01:12 AM

Terry West should be able to make one of these right away for you.
How does the Black Magic downconverter work? I need to get something cause the repair on my Decimator is now a month in waiting.



Thank you for the info i.e. Terry West.

I've only used the Blackmagic a couple of times just for testing purposes and it performed flawlessly, but I was using a nearly dead battery or AC power, so obviously either of these would be untenable in a real life practical application I think, until an inline or in-box voltage reducer were added. It seems to be built well, but Charles mentioned there are some customer service issues apparently with this company.
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