Thread: The SDI issues

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  1. #81  
    Senior Member Robert Hofmeyr's Avatar
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    Quote Originally Posted by Aaron Lochert View Post
    According to this article, the SafeTap doesn't actually protect against this specific fault! It protects the accessory from reverse polarity but it does not help the sensitive SDI problem.



    Via https://rencherindustries.com/blogs/...n-arri-cameras
    Thanks for confirming this Aaron, that is what I thought might be the case.
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  2. #82  
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    Again, page 141 in the operation manual states:

    WARNING: Always attach the power or batteries before attaching the SDI BNC cable. Always remove the SDI BNC
    cable before removing the power or batteries.

    It is quite simple. If you choose to not follow the Komodo operation manual you are on your own. Red put it in the manual for a reason.
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  3. #83  
    Senior Member Robert Hofmeyr's Avatar
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    Quote Originally Posted by Vance Colvig View Post
    Again, page 141 in the operation manual states:

    WARNING: Always attach the power or batteries before attaching the SDI BNC cable. Always remove the SDI BNC
    cable before removing the power or batteries.

    It is quite simple. If you choose to not follow the Komodo operation manual you are on your own. Red put it in the manual for a reason.
    I am aware of that. But I would like more information. There is no way I will always be able to follow the order of operation, so I am looking at other ways to reduce the risk. But I am stuck because we are unsure about the following:

    - Does this apply to batteries used only to power monitors?
    - Does this apply to swapping out a BP-9 while the other BP-9 is running the camera?
    - Is it safer to power both the camera and the monitor from the same power source, or from different sources?

    If it applies to all batteries, and I am powering the Komodo from 2 BP-9s and the monitor from its own battery, then, if any of the batteries need changing, I first need to power down the camera, then remove all 3 batteries, then unplug the SDI, then swap out the dead battery, then re-attach the other two batteries, then re-attach the SDI cable, then reboot the camera. This seems insane.
    Last edited by Robert Hofmeyr; 04-21-2021 at 03:43 AM.
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  4. #84  
    Thank you all for your detailed answers! Also Aaron Lochert awesome, thanks for taking the time and sharing the article about the Safetab not fixing the issue! It even makes it worse, haha. Great news, one less thing I need to buy. After hearing your opinions I'll also forget the Lemos for now, stay with D-Tab and just make extra sure to follow the SDI/ Power Routine. I'm still thinking of buying the Len 3G Galvanic Isolator though, so if anyone has one, would be cool to see your setup!

    Thanks again and have a nice one!
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  5. #85  
    Quote Originally Posted by Robert Hofmeyr View Post
    I am aware of that. But I would like more information. There is no way I will always be able to follow the order of operation, so I am looking at other ways to reduce the risk. But I am stuck because we are unsure about the following:

    - Does this apply to batteries used only to power monitors?
    - Does this apply to swapping out a BP-9 while the other BP-9 is running the camera?
    - Is it safer to power both the camera and the monitor from the same power source, or from different sources?

    If it applies to all batteries, and I am powering the Komodo from 2 BP-9s and the monitor from its own battery, then, if any of the batteries need changing, I first need to power down the camera, then remove all 3 batteries, then unplug the SDI, then swap out the dead battery, then re-attach the other two batteries, then re-attach the SDI cable, then reboot the camera. This seems insane.

    1. Yes its insane.
    2. It applies to all form of power / battery types.
    3. As soon as something with a + and - pol that has any kind of juice in it is connected to your camera, monitor or any other gear that is attached to your camera... you run a risk of frying your stuff if the + pol i connected before the - pol and you got a 12G SDI connection. Some power connectors have a greater tendency to cause this mishap when they are detached or attached. Like Dtap more so than shielded lemo cables. Its basically a shit thing that comes with 12G SDI... Super odd that it has not been sorted before it even became a standard but yes it hits both komodos, LFs and other cameras that use 12G SDI.
    Björn Benckert
    Creative Lead & Founder Syndicate Entertainment AB
    +46855524900 www.syndicate.se/axis
    VFX / Flame / Motion capture / Monstro
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  6. #86  
    Senior Member Robert Hofmeyr's Avatar
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    Quote Originally Posted by Björn Benckert View Post
    1. Yes its insane.
    2. It applies to all form of power / battery types.
    3. As soon as something with a + and - pol that has any kind of juice in it is connected to your camera, monitor or any other gear that is attached to your camera... you run a risk of frying your stuff if the + pol i connected before the - pol and you got a 12G SDI connection. Some power connectors have a greater tendency to cause this mishap when they are detached or attached. Like Dtap more so than shielded lemo cables. Its basically a shit thing that comes with 12G SDI... Super odd that it has not been sorted before it even became a standard but yes it hits both komodos, LFs and other cameras that use 12G SDI.
    Thanks Björn. I don't understand how there could be a danger when connecting a battery and the positive connects first. Before the ground makes contact, the positive does nothing and cannot damage anything (it is a different story when connecting an accessory to an already connected battery, because in that case the ground is already connected via the camera and the SDI cable). When using separate batteries for the monitor and camera, the issue is not ground loops, it is differential grounding (as far as I understand it this is when the two batteries have different ground voltages). This differential will be present no matter how the batteries are connected, until the grounds are connected via the SDI. So, in my understanding, the order of operation specified, makes no sense when using separate power sources for the camera and monitor.
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  8. #88  
    Senior Member Bill Totolo's Avatar
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    Quote Originally Posted by Michael R View Post
    Thanks, Rob. There were no active swaps and the camera was powered down as we were moving from an AC-powered setup on sticks to a v-mount powered setup on gimbal. We filmed the interview (monitor working fine), powered everything down, unplugged AC, unplugged SDI, mounted the Komodo to the RS2, mounted monitor to the RS2 left handle, reconnected SDI, no signal. Tried different cables, different monitors, different batteries, everything. Never got a signal out of the SDI port again.


    Just submitted a support ticket to Red so I'll update you when we hear back.
    It is my understanding that before you disconnected AC power, you should have removed the SDI cable. However, if I am mistaken or misinterpreted your post please feel free to correct me.
    And yes, following this procedure is an unrealistic expectation on set.
    Bill Totolo
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  9. #89  
    Quote Originally Posted by Robert Hofmeyr View Post
    Thanks Björn. I don't understand how there could be a danger when connecting a battery and the positive connects first. Before the ground makes contact, the positive does nothing and cannot damage anything (it is a different story when connecting an accessory to an already connected battery, because in that case the ground is already connected via the camera and the SDI cable). When using separate batteries for the monitor and camera, the issue is not ground loops, it is differential grounding (as far as I understand it this is when the two batteries have different ground voltages). This differential will be present no matter how the batteries are connected, until the grounds are connected via the SDI. So, in my understanding, the order of operation specified, makes no sense when using separate power sources for the camera and monitor.
    I think I´m not mistaken.

    I dont know the exact wording but if you read the Komodo manual it clearly states that.. When fiddling with batteries of any kind, taking them on or off... SDI cable should be disconnected.

    It does not matter if the current is comming from your accessory or the cameras battery slot. Simply put the current that is applied from the + pol will try to find the easiest way to ground or - pol. If the - pol then is not connected, chances are that the easiest path for the current to travel is trough your SDI cable... and viola your SDI graphics board might get fried.
    Björn Benckert
    Creative Lead & Founder Syndicate Entertainment AB
    +46855524900 www.syndicate.se/axis
    VFX / Flame / Motion capture / Monstro
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  10. #90  
    Senior Member Robert Hofmeyr's Avatar
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    Quote Originally Posted by Björn Benckert View Post
    I think I´m not mistaken.

    I dont know the exact wording but if you read the Komodo manual it clearly states that.. When fiddling with batteries of any kind, taking them on or off... SDI cable should be disconnected.

    It does not matter if the current is comming from your accessory or the cameras battery slot. Simply put the current that is applied from the + pol will try to find the easiest way to ground or - pol. If the - pol then is not connected, chances are that the easiest path for the current to travel is trough your SDI cable... and viola your SDI graphics board might get fried.
    Yeah, I'm just trying to get some clarity on why they say that. If you connect only the positive pole of a monitor battery, I don't believe it will cause much current to flow. You can test this with a multimeter - touch one wire to one battery's positive and the other wire to a different battery's negative. The voltage should be very low. Maybe this is enough to fry the SDI? As far as I understand it, once the monitor battery is connected (both positive and ground), there may be a differential in the ground voltages of the two batteries, causing a small current.
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