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12 volts jumper block on PRO Sled


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#1 Juan M.Ramos SOC

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Posted 08 March 2012 - 03:10 PM

Hi Guys;
May be ,it is a stupid question but I wold like to know, is it better to have a "12 volts only" jumper block for powering an Alexa???os is it the same with a regular (3position) jumper block and the sled in 12 volts.
All the best and thanks in advance!!!!!!!
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#2 Fabrizio Sciarra SOC ACO

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Posted 08 March 2012 - 03:41 PM

I'd say the best way to power an alexa from a pro sled is to go the 24 volts way? anybody?
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#3 Alec Jarnagin SOC

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Posted 08 March 2012 - 03:57 PM

Juan,

I always power an Alexa in 24Volt mode with the standard PRO Arri 24 Volt cable.

Cheers,

Alec
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#4 William Demeritt

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Posted 08 March 2012 - 04:10 PM

12v only block puts you in parallel power mode, which allows you to hot swap batteries, while 24v keeps you to cold swaps. As far as watts are concerned, the consumption remains the same, so the hot swap makes it nice over 24v, but you need a 12v Arri power cable. Also any accessories that draw 24v will have more trouble powering.
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#5 Brian Freesh

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Posted 08 March 2012 - 04:14 PM

Why Will? The Alexa is a 24v camera, it converts on-board when fed 12v. Arri recommends feeding 24v though so that the power is more efficient
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#6 Alec Jarnagin SOC

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Posted 08 March 2012 - 04:34 PM

To hot swap in 24 Volt mode, just slap a battery on the back of the camera, change your batteries out, and then remove the onboard.
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#7 William Demeritt

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Posted 08 March 2012 - 04:42 PM

Why Will? The Alexa is a 24v camera, it converts on-board when fed 12v. Arri recommends feeding 24v though so that the power is more efficient


They likely recommend you use 24v configuration because of efficiency since a 12v load at XX watts on a single battery yes is more efficient (higher amps on a single load battery yields less watt hours). 12v load on 2 supplies is just as efficient as a 24v load, considering 24v is made by two batteries, but isn't hot swappable. 12v parallel is hot swappable, and the amps per battery in 12v porallel are the same as the amps per battery in 24v.

The watts is the same, and if the camera doesn't care either way, why not go with the speedier configuration? Like I said, the biggest letdown is buying/building a 12v Arri power cable.
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#8 Brant S. Fagan SOC

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Posted 08 March 2012 - 04:46 PM

I have always run the Alexa as a 12 vdc camera, even with the Codex recorder slung on the rear battery plate. This gives me "shore power" off a block slung on my stand and hot swap with the 24 vdc 2-pin Fischer connector when docked. The Alexa is a 12 volt nominal camera and uses the 24 volt supply simply to run the 24 volt accessories. The internal board determines what power source provides the best electrical potential and draws from that source.

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#9 William Demeritt

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Posted 08 March 2012 - 04:49 PM

To hot swap in 24 Volt mode, just slap a battery on the back of the camera, change your batteries out, and then remove the onboard.


That works too. It's kind of 6 of one, half dozen of the other.
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#10 Juan M.Ramos SOC

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Posted 08 March 2012 - 06:39 PM

Thanks Guys,
GPI-PRO is not making this jumper anymore,also I think I don't need it but Thanks.
Thanks gosh my Sled is a Ultimate 2!!!!!...but the rest of my company is running PRO.
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#11 William Demeritt

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Posted 08 March 2012 - 06:51 PM

Thanks Guys,
GPI-PRO is not making this jumper anymore,also I think I don't need it but Thanks.
Thanks gosh my Sled is a Ultimate 2!!!!!...but the rest of my company is running PRO.


Hey, in the event of an EMP blast or explosion, my PRO sled will still work. ;)
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#12 Brian Freesh

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Posted 08 March 2012 - 07:34 PM

Sorry Will, I was vague. I meant why would powering 12v affect the accessory outputs? The camera is a 24v camera, the accessory ports never change. Supply the camera 12v and it converts to 24v, which is why Arri recommends supplying 24v.
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#13 William Demeritt

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Posted 08 March 2012 - 07:46 PM

Sorry Will, I was vague. I meant why would powering 12v affect the accessory outputs? The camera is a 24v camera, the accessory ports never change. Supply the camera 12v and it converts to 24v, which is why Arri recommends supplying 24v.


On the PRO sled, using the 12v power block disables the second battery from running to the AUX power port on the upper junction box. Likewise, all remaining ports up top become 12v, so you have nowhere to power 24v only accessories unless coming off the camera accessory ports that give out 24v.
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#14 Brian Freesh

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Posted 08 March 2012 - 08:16 PM

Ah, thought you were saying it was changing the camera's power outs, my B.
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