HD-SDI connection between cameras and video mixers

[Promoter2000]

Hello everyone. I need to connect two HDV camcorders (Sony HVR-S270) to the Panasonic AG-HMX100 video mixer in SDI. I read that the SDI ports of the camcorders can burn out due to overvoltages if the connection sequence to the peripherals is not correct (in practice I read that the SDI peripheral must always be connected ALREADY TURNED ON to the SDI port of the camera and disconnected from the camera in the same way). In the same way, the batteries that power the camcorders must be changed when they run out. My doubt now is this: in the case of a permanent connection (the placement is fixed) to avoid problems should I always turn on the Panasonic mixer first and only then the two camcorders or could I also do the opposite? Since the two camcorders would be powered exclusively by batteries, to change the batteries during shooting would it be enough to turn off the camera and then turn it on again or would it be necessary to also turn off the video mixer? Thanks everyone.

[aramkolt]

Hmm. I was unaware of this, but I see several videos online about it now. Seems they describe it as being more of a problem with 12G than 3G which I believe HDV camcorders are probably 3G, but apparently it can happen with 3g as well.

Even after watching a couple of videos, it's not particularly clear which videos are correct, but it sounds like the issue is that you could get a spike during a power on sequence or when connecting a battery initially on the ground/shield pin *if* both devices are ungrounded to earth ground - ie if you're using two battery powered devices or devices that only use 2 pin power connectors from switching power supplies that typically are isolated from earth ground at the outputs.

In your case, if you connect your mixer to earth ground and leave it connected and verify that the ground pin on the input actually has continuity with the SDI's jacket (which I would be very surprised if does not), I don't think it matters the order of power up or even hot plugging of your camera while both are on.

From my interpretation, The only way you could really cause damage unintentionally with the HMX100 in the chain would be to use a power cable that has the ground pin removed going into the mixer, but I'd be curious to hear others opinions on how this works as well as I may be wrong.

[Promoter2000]

From what I've seen, it seems that the risk is the same for any type of SDI (3/6/12 G). Everyone says that to be safe, just connect the SDI to the camera last (that is, only after turning on the mixer and camera) and disconnect it first (that is, at the end of filming, first disconnect the SDIs from the cameras and only then turn off the mixer and cameras). All the examples I've seen, however, concern occasional setups; none have concerned a fixed setup (such as a television studio). Perhaps, to be safe, I should follow this procedure every time too: first turn on the mixer and cameras and only then connect the SDI outputs with the end of the cable coming from the mixer. Once filming is over, first disconnect the ends of the camera cables from the SDI outputs and only then turn off the mixer and cameras. Between one shot and another, I should always leave the camera cables disconnected from the SDI outputs of the camcorders.