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Arri Alexia power


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#1 Rogerhaugen

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Posted 25 August 2010 - 05:41 PM

Hi!

I am using the new Arri Alexa these days on my Mk-V Nexus sled. When using onboard batteries on the camera it runs on 12v. But when using external power from the sled you will be using the regular Arri 24v plug. When doing so thru my sled it said about 13,5 volt in the display not 24v or more, Everything was working, but, the voltage display kept blinking 13,5v. I know this camera can run on both 12v and 24v, but can run on 12v this way?

The camera assistant got worried and called the rental house because it was blinking and they said we couldn´t run it like that or they didn´t really know. I have not called Arri yet about this.
So for now I am stuck with on board batteries. Anyone?

Best
Roger Haugen
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#2 Jens Piotrowski SOC

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Posted 25 August 2010 - 06:11 PM

Hi!

I am using the new Arri Alexa these days on my Mk-V Nexus sled. When using onboard batteries on the camera it runs on 12v. But when using external power from the sled you will be using the regular Arri 24v plug. When doing so thru my sled it said about 13,5 volt in the display not 24v or more, Everything was working, but, the voltage display kept blinking 13,5v. I know this camera can run on both 12v and 24v, but can run on 12v this way?

The camera assistant got worried and called the rental house because it was blinking and they said we couldn´t run it like that or they didn´t really know. I have not called Arri yet about this. I am not sure if there is a problem with my sled or if I have to switch something on the camera.
So for now I am stuck with on board batteries. Anyone?

Best
Roger Haugen



the camera runs internally on 24V and uses about 85W. please measure the voltage coming out of your sled and make sure that is at least 24V.

from ARRI:

"Power Management
When using the BAT connector and one or more onboard battery
adapters at once, the camera power management ensures that always
the power source with the highest voltage level is used. When the
voltage level of one power source drops below the level of the other, or
a power source is disconnected from the camera, the power
management automatically switches to the other power source,
avoiding shutdown of the system.
So as an example, one could use a 12 V onboard battery as backup for
the main 24 V battery, or power the camera from the 24 V battery while
on a tripod and use the 12 V battery for fast switching to handheld
mode by just unplugging the power cable.
When using two onboard battery adapters with batteries in parallel,
they are treated as one source by the camera. This allows combining
small batteries with less load per item into one strong power source."

"What is ALEXA's power input?

ALEXA accepts an input voltage range from 11 to 34 V DC through the BAT connector and the on-board battery adapters. The camera will automatically pick the power source with the highest voltage. Power sources can be hot plugged. Battery adapters are available now for the back of the camera, and will be available soon for the top of the camera. There are different battery adapters available for either V-lock or Gold mount batteries.

The power supply should deliver an output of more than 90 W to power the camera sufficiently. The power draw of the camera and viewfinder in basic configuration is about 85 W. Please note that using a 24 V power source is more efficient than using a 14.4 V source, as ALEXA uses 24 V internally."
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#3 thomas-english

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Posted 26 August 2010 - 03:33 AM

If measuring the voltage out of the 3 pin lemo's is a little tricky. Could you try the following:

Plug the Alexa into one of the power outs at the Bottom of your sled.I know you might not be able to work like that but its a test.

What D and J box are you using? When did you buy your centre cable? I am assuming you are using a 4 stage post?
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