Blackmagic Forum

Is it possible to power the video assist 4k from the Blackmagic V-Mount plate P-Tap port? It is 12V 1.5A.

Yes its a good choice, 12v and regulated, its the way I power mine

Thanks.

John Simpson wrote:Yes its a good choice, 12v and regulated, its the way I power mine

Kim Janson wrote:The smaller VA works ok from d-tab download/file.php?id=12091

You Sir are playing with fire!! From the regulated Dtap on the Ursa camera Yes sure no problem.. From a Vlock battery with up to +18V when fully charged and "no load" you could blow the VA power circuits!!.

I opened up the VA to check it's power circuits. The power regulator inside that regulates the 12V input power has an Absolute MAXIMUM rating input voltage of 14 or 15 Volt(not sure have to seek for a topic about 2 years ago were i documented this..). A standard Vlock is default 14.4V and if charged it could be up to 18V..

EDIT: The topic for reference!! viewtopic.php?f=4&t=44856&p=259878&hilit=dtap+va#p259845

So powering your VA directly from a Dtap is voiding your waranty.. Don't expect to get a new one if you fry it..

I'm pretty sure it is risky.. (Hardware software developer myself) Will open up the VA and hand out the part number here.. With the datasheet to it..

Okee To set things straight!! I opened up the VA again.. Did a checkup and the Main Power regulator is a Linear Technology LT3503. http://cds.linear.com/docs/en/datasheet/3503f.pdf

Which states in their datasheet: 5V at 1A from 7.2V to 18V Input

So it seems i was wrong.. Maybe i had another datasheet 2 years ago.. Maybe there is something changed.. I dunno. (The one i opened up back in the days was 1 of the first production models.. Not sure if they changed it.. )

Absolute maximum rating of this chip is 20V.

The 7.2V under limit for 5V output could explain why the VA batteries are empty so quickly.. As those are 7.4V nominal power.. So fully charged they will be in the ball park of 7,8V.. Drop down quite fast to 7,4.. And at 7.2V the meter will say RED empty.. But it is good to know that you CAN power the VA from Vlock!

Sorry guys for mis directing you guys..

No worries, thanks for the update.


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Daniel, I had rested one of the first VAs with 17.5VDC from an AB gold mount battery, no issues. Back then BM did tell me the VA could take 7.3-18VDC. However, I did end up using a 12VDC regulated DTap to BMCC power cable I had from IndiePro.
Cheers