Warning about SDI cable connection

[Paul Kalbach]

I'm puzzled by this warning on page 79 of Komodo Operation Guide:

" WARNING: Always connect the DC power cable (or batteries) before connecting the BNC SDI cable. Always remove
the BNC SDI cable before removing the DC power cable (or batteries)."

I've never run across a warning like this in operating any other camera. What is likely to happen and why, if this warning isn't followed? Seems like someone could accidentally not follow this procedure while in a rush! FedEx will be ringing my doorbell any minute today to deliver my Komodos, so this would be a good thing to know about...

 

[Jack Allred]

sdi can complete a circuit when unshielded power cables are connected

https://www.facebook.com/TeamARRI/videos/239411913728635/

https://www.arri.com/resource/blob/...b216c/download-technical-information-data.pdf

 

[Paul Kalbach]

Thanks Jack...I never knew that!
Also, I just realized I have no 12G SDI cables...just 3G. Is 3G going to work at all...or just not up to optimum performance?

 

[Rakesh Malik]

There's a risk of blowing out your SDI transmitter, which IIRC is related to cable impedence.

 

[Christoffer Glans]

This is true on every camera with SDI. People just don't read the manuals as much with rental gear :tongue_smilie:

 

[Paul Kalbach]

Thanks guys! Hmmmm....so even though my SmallHD Cine 7 and Focus 5 monitors are limited to 3G SDI, I still need 12G cable to protect the Komodo's output? Just how risky would it be to use 3G cable? My two Komodos just landed minutes ago...

 

[kylebainter]

Is there a way to use an in line bnc limiter or similar to not worry about a surge? To change a v mount or other battery and need to remove sdi each time is insane.

 

[Chris Sharman]

I’ve not heard of this either, and the RED guide doesn’t give much context.

However the Arri paper seems to suggest that it refers to the power/battery for whatever accessory you’re in the process of connecting, which would make sense.

I.e., if you’re plugging in a teradek, make sure to plug in the power cable to the transmitter first, before connecting to the SDI. Otherwise the process of plugging in the power can lead to a surge back into the SDI drivers through the already connected cable.

Another interesting takeaway is that D-tap power cables are always vulnerable to this as they can’t be shielded.

That’s my interpretation anyway, correct me if I’ve got that wrong and would be good to hear clarification from RED as reading their manual it could well be assumed they are talking about the camera battery.

 

[Alex Lubensky]

Thanks guys! Hmmmm....so even though my SmallHD Cine 7 and Focus 5 monitors are limited to 3G SDI, I still need 12G cable to protect the Komodo's output? Just how risky would it be to use 3G cable? My two Komodos just landed minutes ago...

You can use any cable you want, be it 3g, 6g, 12g or 1.5g. It's the speed of the cable, not the quality of connectors.

And yes, you can damage your camera with SDI, especially this is true when connected straight to the client playback monitors via cable, and they are feeding of DC.

 

[Ivan K. Maras]

Does that mean we have to unplug the sdi cabe before swapping batteries too?

 

[Ivan K. Maras]

Also found this response in the Facebook group: "The shielded recommendation applies to the actual power cable for accessories connected via SDI, not the actual SDI cable." Can someone confirm this?

 

[Alex Lubensky]

Swapping batteries is ok, no need to reconnect the sdi if it’s connected to the onboard monitor.