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Matthias Bender

short after connecting the monitor

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That is what we found out: The Marshall monitor uses one ground for both - sdi and power.

 

So when the sled is powered on (12V or 24V) and you connect the multicable to the monitor first (SDI and power) and connect the multicable to the sled after everything else is connected, the plus-pin might have contact before the minus-pin. So the power runs from the battery through the SDI line into the SDI-board, to the the multicable.

 

That is my theory. I can not prove it. But do you think that is possible according to your cases?

 

Greetings from Munich!

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Hi Matthias and Zhong Wei,

that sounds about right and goes for other gear transmitters etc that might share earths

As I mentioned before I never really got to the bottom of my problem but now try to attach everything before powering up not always possible but good general practice.

All best

Joe

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Having SDI and power grounds tied together in and of itself shouldn't be a problem and should actually be the proper way of doing things. I would guess that if the BNC connector on the monitor actually had a better ground connection this would not happen as the path of least resistance would no longer be through the part of the SDI board that is frying.

 

If you plug the 4 pin XLR in last this shouldnt happen. It is designed so that the ground pin always mates before the hot. Wish all connectors were like that.

 

~Jess

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Yup, I've replaced my SDI board on my Marshall twice now.

Bringing this back from the dead....

 

Alan what caused the issue of your SDI module going out? Mine recently failed months after shorting out a connection when plugging in the monitor.

 

But is the general consensus to have everything plugged in before powering up?

 

I did notice my Marshal V-LCD70MD-3G does have a note saying to specifically not hot swap SDI inputs which I've never heard....

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Bringing this back from the dead....

 

Alan what caused the issue of your SDI module going out? Mine recently failed months after shorting out a connection when plugging in the monitor.

 

But is the general consensus to have everything plugged in before powering up?

 

I did notice my Marshal V-LCD70MD-3G does have a note saying to specifically not hot swap SDI inputs which I've never heard....

 

To be honest, I would either steer clear of Marshall monitors or install a less sensitive device in between the sled and monitor. Freakshow has a tiny DA that would work, or you could use an AJA, Decimator, Blackmagic, converter. I would follow the note about not hot swapping, if that's what the manufacturer recommends. It could be that the power surges when hot-plugging, and that's what's causing the problem (just a guess).

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I have never had a problem with my Marshall but I always have power plugged in before putting batteries on the sled. I even hot swap BNC's regularly but if you want to be extra careful don't do that I guess. Also don't plug in hot power with BNCs attached. The problem seems to be situations where ground power runs over the BNC instead of the power cable. So a bad ground in a power cable can kill the SDI board or hot plugging power with a BNC already attached.

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