Preventing Damage to SDI Outputs

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Leon Benzakein

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Preventing Damage to SDI Outputs

PostSat Feb 15, 2020 4:33 pm

This subject has been discussed many times.
This may help.

Hopefully this applies to HDMI as well.

https://www.newsshooter.com/2020/02/15/ ... i-outputs/
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Howard Roll

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Re: Preventing Damage to SDI Outputs

PostSat Feb 15, 2020 8:13 pm

The comments are far more informed than the article. I don't even disconnect SDI when I'm terminating new ends. The real news here is that everybody, even Arri, is using increasingly cheaper materials in their products. In what universe could a television station or even small studio exist if you had to power down every time you needed to make a new patch?

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John Brawley

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Re: Preventing Damage to SDI Outputs

PostSun Feb 16, 2020 7:04 am

Howard Roll wrote:The comments are far more informed than the article. I don't even disconnect SDI when I'm terminating new ends. The real news here is that everybody, even Arri, is using increasingly cheaper materials in their products. In what universe could a television station or even small studio exist if you had to power down every time you needed to make a new patch?

Good Luck


It’s not about “cheap” materials.

The problem is that you can’t have high speed over SDI (like 6g or 12g) with any protection from shorts because they are incompatible.

JB
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MadPanic

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Re: Preventing Damage to SDI Outputs

PostSun Feb 16, 2020 10:16 am

John Brawley wrote:
The problem is that you can’t have high speed over SDI (like 6g or 12g) with any protection from shorts because they are incompatible.

JB


I use a passive in-line galvanic isolator which electrically isolates between camera and other device. The one I have is 3G as I use it for monitoring from the front SDI, but 12G ones are available such as:

https://www.canford.co.uk/Products/90-6 ... 2G-UHD-SDI
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rick.lang

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Re: Preventing Damage to SDI Outputs

PostSun Feb 16, 2020 4:04 pm

Gulp! Safety doesn’t come cheap, but less expensive than burning a connection on the camera.
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John Brawley

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Re: Preventing Damage to SDI Outputs

PostSun Feb 16, 2020 4:10 pm



It's great that this exists. I think this might be a new item.

Also...

It's a US $440 part.

My understanding is that while there IS a way to protect the SDI connection, that it would no longer be able to qualify as a 12G connection once that part is fitted.

The link you provided does mention 12G, so maybe they have a way around that now, however, I can't imagine them adding this as an item if that is the unit cost.

Last time I talked to my friends at BMD they basically said it was impossible to protect the SDI and have it qualify as 12G. Maybe that's changed recently.

Also, this has been a problem for ALL SDI fitted cameras for a long time. Hence Arri issuing a warning post about it.

JB
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MadPanic

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Re: Preventing Damage to SDI Outputs

PostSun Feb 16, 2020 8:33 pm

rick.lang wrote:Gulp! Safety doesn’t come cheap, but less expensive than burning a connection on the camera.


My camera had to go back for repair of the SDI output, so I'm taking no chances, but my use case is 3G SDI for monitoring only, so the isolator is cheaper than the one in the link shared. Once burned, etc, but because of the cost, I am very careful where I put the isolator because it can easily be mistaken for just some connector and left on a cable.
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Re: Preventing Damage to SDI Outputs

PostMon Feb 17, 2020 12:06 am

Shielded DC power cable feels like partial speculation because formally it is not shield but just additional (-) wire which touches ground before other (-) and (+) wires for additional safety.

:arrow: But this info is really useful:
"This damage to the SDI connection can occur when connecting an unshielded power cable to an accessory that is already connected to the SDI output of the camera. If the plus pin is contacted before the negative pin, the BNC cable will close the current circuit resulting in the fatal damage of the included SDI driver chip which itself is not designed to handle such high currents. "

This probably explains what caused the HDMI port damage on my camera when i power my camera and monitor with early prototype 18650 battery enclosure (ground looped connection). That battery prototype has on/off switch connected to negative (-) cable because because it was easier to arrange cables layout like this. I usually connected all cables to camera and then turn that switch ON. And once upon a time camera was turned ON but it was no HDMI signal.

When i moved to batch manufacture i decide to redesign cables layout and connect on/off switch to positive (+) cable, just to match common recommended guidelines for electronics. So lucky to know now that all my battery enclosures are formally safe, and formally seems like protect from ground loop damages.

This is probably the main discovery about ground loop connection damages "mystery" - never connect positive (+) DC power cable pin until you connect negative (-) pin.
Actually it is not so easy to do in real life until you have dedicated switch on positive wire of DC cable, or specially designed DC connector which 100% always connects (-) pin before (+) pin.
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Dmitry Shijan

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Re: Preventing Damage to SDI Outputs

PostTue Feb 25, 2020 10:41 am

Also i noticed that LP-E6 BMMCC battery slot also specially designed to connect (-) pin before (+) pin. You can see extending (-) contact at the left side.

Image
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