The SDI issues

[Robert Hofmeyr]

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/technical-advisories/hot-plugging-devices-on-arri-cameras

Thanks for confirming this Aaron, that is what I thought might be the case.

 

[Vance Colvig]

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.

 

[Robert Hofmeyr]

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.

 

[Amarin Spörri]

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!

 

[Björn Benckert]

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.

 

[Robert Hofmeyr]

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.

 

[Bill Ravens]

https://www.facebook.com/photo.php?fbid=2365065946971482&set=p.2365065946971482&type=3

 

[Bill Totolo]

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.

 

[Björn Benckert]

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.

 

[Robert Hofmeyr]

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.

 

[Bill Ravens]

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.

Your test is a static, steady state test. You would need an oscilloscope to test for a very short but high amperage pulse undetectable by the inertia of conventional DVM's.

 

[Blair S. Paulsen]

AFAIK, right before any hot power source fully mates with a device, it gets close enough for some electrons to jump the air gap and cause a very brief voltage surge. During that fleeting moment, voltage fluctuations outside of rated specs can occur. Proper grounding will dissipate stray current to protect the electronics. However, if the - pol of the battery plate engages second so that briefly, the only available path to ground is via the SDI tap - it might not take much to fry the SDI board.

FWIW, getting a dedicated power distro accessory from someone like Wooden camera is the obvious solution. Yes, there are cost and weight considerations - but if you're using your Komodo on a busy set, I agree with other posters about the impracticality of 100% compliance with the protocols specified in the manual. If, for whatever reason, you don't want to add another device to your Komodo, I'd start with making a label to stick on the camera that lists the order in which things are done during power swaps. In addition, ideally, do all the power swaps yourself.

Cheers - #19

 

[Robert Hofmeyr]

Your test is a static, steady state test. You would need an oscilloscope to test for a very short but high amperage pulse undetectable by the inertia of conventional DVM's.

Thanks Bill. That must be the part I was missing with my rather basic electronics knowledge. So when connecting a battery to the monitor, and there is already a battery on the camera, and the positive connects before the negative, there can be a high amperage pulse that damages the SDI? And do you know if this can happen if I have the monitor powered by battery and the camera powered by two batteries, and I change one of the camera batteries?

 

[Robert Hofmeyr]

AFAIK, right before any hot power source fully mates with a device, it gets close enough for some electrons to jump the air gap and cause a very brief voltage surge. During that fleeting moment, voltage fluctuations outside of rated specs can occur. Proper grounding will dissipate stray current to protect the electronics. However, if the - pol of the battery plate engages second so that briefly, the only available path to ground is via the SDI tap - it might not take much to fry the SDI board.

FWIW, getting a dedicated power distro accessory from someone like Wooden camera is the obvious solution. Yes, there are cost and weight considerations - but if you're using your Komodo on a busy set, I agree with other posters about the impracticality of 100% compliance with the protocols specified in the manual. If, for whatever reason, you don't want to add another device to your Komodo, I'd start with making a label to stick on the camera that lists the order in which things are done during power swaps. In addition, ideally, do all the power swaps yourself.

Cheers - #19

Thanks Blair. And do you know if connecting the chassis of the camera with the chassis of the monitor (assuming it's metal) will provide a common ground through which the current can run preventing damage to the SDI?

 

[Björn Benckert]

AFAIK, right before any hot power source fully mates with a device, it gets close enough for some electrons to jump the air gap and cause a very brief voltage surge. During that fleeting moment, voltage fluctuations outside of rated specs can occur. Proper grounding will dissipate stray current to protect the electronics. However, if the - pol of the battery plate engages second so that briefly, the only available path to ground is via the SDI tap - it might not take much to fry the SDI board.

FWIW, getting a dedicated power distro accessory from someone like Wooden camera is the obvious solution. Yes, there are cost and weight considerations - but if you're using your Komodo on a busy set, I agree with other posters about the impracticality of 100% compliance with the protocols specified in the manual. If, for whatever reason, you don't want to add another device to your Komodo, I'd start with making a label to stick on the camera that lists the order in which things are done during power swaps. In addition, ideally, do all the power swaps yourself.

Cheers - #19

Question, What makes you think the Wooden camera power distro accessory would make things more safe?

 

[Jacek Zakowicz]

AFAIK, right before any hot power source fully mates with a device, it gets close enough for some electrons to jump the air gap and cause a very brief voltage surge. During that fleeting moment, voltage fluctuations outside of rated specs can occur. Proper grounding will dissipate stray current to protect the electronics. However, if the - pol of the battery plate engages second so that briefly, the only available path to ground is via the SDI tap - it might not take much to fry the SDI board.

FWIW, getting a dedicated power distro accessory from someone like Wooden camera is the obvious solution. Yes, there are cost and weight considerations - but if you're using your Komodo on a busy set, I agree with other posters about the impracticality of 100% compliance with the protocols specified in the manual. If, for whatever reason, you don't want to add another device to your Komodo, I'd start with making a label to stick on the camera that lists the order in which things are done during power swaps. In addition, ideally, do all the power swaps yourself.

Cheers - #19

I just can't conceive a "circuit" if the negative battery terminal is hanging in the air- there is no circuit- plain and simple circuit is open. It's like voltage wasn't there until you connect the negative terminal. I agree with Robert..

 

[Blair S. Paulsen]

I'm going by this note on Wooden's site:

Three D-Taps on the plate provide battery voltage for accessories and power is monitored for over-current. If more than 5.8A are used by accessories, a digital fuse will trip and the red LED will illuminate but the camera will remain powered. Reset button can be pressed once to restart accessory power.

I have not personally tested its ability to protect the SDI board, or any other part of the Komodo. Perhaps Ryan can chime in on what their plate solution can, and cannot do to protect your rig from surges/ground loops/etc.

I still think the ideal solution is a plate with a short run internal battery and a capacitor. To be clear: I am NOT an electrical engineer, just an experienced production pro.

Cheers - #19

 

[Robert Hofmeyr]

Another question: if galvanic isolators effectively prevent these problems, why is there not one inside the camera already? Is there a downside to using one?

 

[Blair S. Paulsen]

Thanks Blair. And do you know if connecting the chassis of the camera with the chassis of the monitor (assuming it's metal) will provide a common ground through which the current can run preventing damage to the SDI?

In theory, creating a common ground via a metal to metal connection between devices should work. That said, the internal circuitry of any particular device may or may not use its casing as ground. Then there's the issue with plastic casing...

I'm from Sean Fairburn's school of test, test, test so typically I'd just find out for myself. Unfortunately, the risk of frying the SDI board and having to send the Komodo back to RED for repair is too great...

Cheers - #19

 

[Robert Hofmeyr]

I'm going by this note on Wooden's site:

Three D-Taps on the plate provide battery voltage for accessories and power is monitored for over-current. If more than 5.8A are used by accessories, a digital fuse will trip and the red LED will illuminate but the camera will remain powered. Reset button can be pressed once to restart accessory power.

I have not personally tested its ability to protect the SDI board, or any other part of the Komodo. Perhaps Ryan can chime in on what their plate solution can, and cannot do to protect your rig from surges/ground loops/etc.

I still think the ideal solution is a plate with a short run internal battery and a capacitor. To be clear: I am NOT an electrical engineer, just an experienced production pro.

Cheers - #19

I don't think a ground loop will result in over-current. AFAIK it is not a short circuit - the accessory is just using the wrong path to get to ground but it will pull the same amps as normal.