Blackmagic Forum

Hi,

since I had one of these lying around

https://shop.sommercable.com/Kabel/Meterware-Audio/BUS-Steuerkabel-SC-Kolorith-MINI-500-0111-1.html

I wanted to built an extension cord of 15m length with 1 XLR 4 pin and 1 XLR 3 pin on each side for transmitting intercom and 12V power. The idea was to use the 12V URSA Broadcast power adapter. But whenever I try to power up the camera it won't start. It tries to, but it seems to get stuck in a startup procedure (there is a clicking sound of something switching, which one will hear only once when the power adapter is connected directly to the camera). I checked the polarity of course.

How much power does this camera need, when starting? I thought that the diameter of 2x1mm² should be enough?

Of course, I could try to use 240V, but then the power adapter has to be mounted on the camera side, which is sort of ugly.

Anyone?

Knut

Hi Knut, I don't have direct experience of the Ursa, but had a similar problem with the older Studio HD and Studio 4K cameras. They stopped responding reliably to their own small 12V AC adaptor power supplies when they were plugged directly into the cameras! The problem was intermittent at first, and a camera operator would suddenly announce that their (built-in) battery was close to zero in the middle of an all-day live stream. I discovered that the only cure was bigger PSUs, such as 13.8V 4.3A IDX designed for bigger cameras. After testing I eventually purchased a set of small 12V 5A PSUs (to keep size and weight down, we travel a lot) which have worked reliably since. I can only assume that the same is happening, either the Voltage or Amperage is dropping too low over the longer cable for the camera to switch on.

Ursa Broadcast Power Supply - 12V/8A
loss on your cable - 4.3V (with full load)
The camera operates at a voltage of 12-20V.

For example - cable loss on 5,00 mm² cable - 1V. (power 12V/8A)

The easiest way is to use a 20V power supply and your cable will work.

As above, it's the voltage drop across the length of cable your using.

From my mobile using Tapatalk

The Vlock power input is 12-20V. But the XLR 4 pin says 12V next to the connector. I have had 14V power supplys on that one. But it is not guaranteed this input can also up to 20V. Bit of tricky...

Yes, but since it is a stsndard 4-pin 12VDC connection, and 1#VDC batteries can be as hi as 14.5-16VDC, it should handle these voltages. I connected my Broadcast to a 12-volt sealed battery, no issues.
Another Q for BMD
Cheers

Thanks guys for the insight.

Xtreemtec wrote:The Vlock power input is 12-20V. But the XLR 4 pin says 12V next to the connector. I have had 14V power supplys on that one. But it is not guaranteed this input can also up to 20V. Bit of tricky...

So it will probably be better using a 240V V-mount powersupply or I simply stick to batteries.

Thanks again.

Or put a Vlock plate on the back with power in up to 18/19 volts. Could work. Feeding 230V over a 2 wire cable without ground is also not really up to code..

Xtreemtec wrote:Feeding 230V over a 2 wire cable without ground is also not really up to code..

"Mut zur Lücke" (no risk no fun) - as we Germans say

Seriously, I forgot that there is no ground. 240V is a no go here.

Xtreemtec wrote:The Vlock power input is 12-20V. But the XLR 4 pin says 12V next to the connector. I have had 14V power supplys on that one. But it is not guaranteed this input can also up to 20V. Bit of tricky...

Manual, page 7
To plug in external power:
1 Connect the AC to 12V DC adapter plug to your mains power socket.
2 Connect the AC to 12V DC adapter’s 4 pin XLR connector to the 12-20V DC power
connector on the camera.

So there you have it, the 4-pin xlr takes the industry 12-20VDC input.
Cheers

Does anyone know if there are any off-the shelf 4-pin xlr DC power cables that work (or should work) with the URSA Broadcast? Also, what is the theoretical max length for such a cable? We're running an AC/Extension with our SDI cables and that isn't ideal from a signal standpoint.

Any good commercially available 4-pin power cable should work. I have used ones, that I originally got for a Sony BetaCam camera. That said, these power cables are designed for short runs, of less than 3 meters (7-feet), and more common ones are only 1-meter/3-feet long, as they are designed to work with a AC/DC power supply located close to the camera or from a aux camera battery as a backup power source tomthe battery mounted on the back of the camera. The BMD Camera Fiber Converter can also power the camera with longer cable runs connecting to a power source in the control room,

The Blackmagic Camera Fiber Converter attaches to the back of your
URSA Broadcast camera so you can use and power it remotely from a Blackmagic Studio Fiber Converter up to 2 km away.

Cheers

Linden deCarmo wrote:Does anyone know if there are any off-the shelf 4-pin xlr DC power cables that work (or should work) with the URSA Broadcast? Also, what is the theoretical max length for such a cable?

It’s all relative. Plug the numbers into a line loss calculator to see how far you can go. 12v is terrible over distance. If you’re trying to use DC at more than 10-20ft use 18v power supplies, 12v isn’t going very far before it’s unusable.

https://www.rapidtables.com/calc/wire/v ... lator.html

Good Luck