Not safe to power monitor and camera from same power source?

[Jeremy Clark]

I was looking at some power options for a BMP4k and Shinobi monitor, and like the idea of powering both from one system, but noticed in the demo video the guy said his HDMI port went out. In the comments, someone mentioned that it a bad idea to power both from the same power source if you are connecting the two via another cable (HDMI/SDI) as you could have some sort of unintended voltage/ground issue that can fry the video port. I can see that as being completely possible, but wanted to know if you guys had any thoughts/experience? Not something I'm really willing to just go out and test! 

Just now, Jeremy Clark said:

I was looking at some power options for a BMP4k and Shinobi monitor, and like the idea of powering both from one system, but noticed in the demo video the guy said his HDMI port went out. In the comments, someone mentioned that it a bad idea to power both from the same power source if you are connecting the two via another cable (HDMI/SDI) as you could have some sort of unintended voltage/ground issue that can fry the video port. I can see that as being completely possible, but wanted to know if you guys had any thoughts/experience? Not something I'm really willing to just go out and test! 

My initial thought is maybe it has to do with trying to draw different voltages at the same time - ~7.4 for the monitor, and ~12 for the camera (if using the side port vs the battery port). 

[bjohn]

See https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=110368

I always use separate batteries for monitor and camera. I know plenty of people use the same battery to power both, but it can be risky.

[Jeremy Clark]

25 minutes ago, bjohn said:

See https://forum.blackmagicdesign.com/viewtopic.php?f=2&t=110368

I always use separate batteries for monitor and camera. I know plenty of people use the same battery to power both, but it can be risky.

Yeah, makes total sense. Not gonna bother risking. 

[UncleBobsPhotography]

The case which is linked to powered both cameras from the same V-lock battery. My monitor came with a dummy battery for powering my camera from the monitor (SWIT).

I hope this is a sign that the they have thought of the problem and found a solution for it. Does anyone have any examples of the monitor frying the HDMI even when it was made for powering the camera?

[Anaconda_]

I power my BMPCC4k and 5inch Video Assist with the same V-mount battery and haven't had any issues. I use this mount on my rig:

I

I run a dummy battery from the 7.2v output into the camera. I've heard of people having issues using dummy batteries that deliver too much power, so this limits to 7.2v, which, if memory serves, is about the same as a half charged LPE6. Then I use a D-Tap to  power the monitor.

It's a neat solution because no cables connect direct to the battery, which makes swapping extremely quick and easy. 

The downside is, I don't have the backup of a real LPE6 in the camera. If I did, I could hotswap V-mounts and never have to turn the camera off. The plus side, is my rig is neat and tidy, hardly any visible wires and I can put it away in a bag without snagging cables that are hanging out of the ports.

[EphraimP]

27 minutes ago, Anaconda_ said:

I power my BMPCC4k and 5inch Video Assist with the same V-mount battery and haven't had any issues. I use this mount on my rig:

I

 

I use a different V-Mount plate, but other than that, my solution to powering my X-T3 rig and Ninja V is the same. I use a dummy battery for my Camera and a 12v cable for the monitor. I've been doing this for about a year with no problem. I've also been using a Powerextra NP-F960 style battery with USB and DC outlets to power my X-T4 and another Ninja. I plug the battery directly to the Ninja and use a USB to USB C cable for the T4. I haven't used this as much, but no problems yet.

[Hangs4Fun]

On 8/27/2020 at 11:15 AM, UncleBobsPhotography said:

The case which is linked to powered both cameras from the same V-lock battery. My monitor came with a dummy battery for powering my camera from the monitor (SWIT).

I hope this is a sign that the they have thought of the problem and found a solution for it. Does anyone have any examples of the monitor frying the HDMI even when it was made for powering the camera?

Simplest thing to do here is have a safe workflow when setting and taking down your camera rig.  In the example where you have a camera and a recorder/monitor both receiving power from the same power source, yet have a high frequency connection between the camera and recorder/monitor like SDI 6G/12G or HDMI 2.0/2.1 and unshielded cabling is used.  Simply following:

- When connecting: FIRST connect power cables, THEN HDMI / BNC.
- When disconnecting: FIRST disconnect the HDMI / BNC, THEN the power.

Also helpful is using shielded power cables and avoiding D-tap connectors (since they can possibly be plugged in backwards).  To safeguard your D-tap connector you could add the Lentequip Safetap which protects against reverse polarity, over/under voltage, and short circuits, as well as preventing battery deep discharge.  

But just following the connect/disconnect process above should protect you most of the time.

[Hangs4Fun]

On 8/29/2020 at 11:54 AM, Hangs4Fun said:

Simplest thing to do here is have a safe workflow when setting and taking down your camera rig.  In the example where you have a camera and a recorder/monitor both receiving power from the same power source, yet have a high frequency connection between the camera and recorder/monitor like SDI 6G/12G or HDMI 2.0/2.1 and unshielded cabling is used.  Simply following:

- When connecting: FIRST connect power cables, THEN HDMI / BNC.
- When disconnecting: FIRST disconnect the HDMI / BNC, THEN the power.

Also helpful is using shielded power cables and avoiding D-tap connectors (since they can possibly be plugged in backwards).  To safeguard your D-tap connector you could add the Lentequip Safetap which protects against reverse polarity, over/under voltage, and short circuits, as well as preventing battery deep discharge.  

But just following the connect/disconnect process above should protect you most of the time.

Easy way to remember that cabling sequence, is that you always start and end with power

[herein2020]

22 hours ago, Hangs4Fun said:

Easy way to remember that cabling sequence, is that you always start and end with power

Had no idea this could happen, I power my monitor with a dummy battery and v mount plate adapter as well. Is this still possible even if the v-mount plate is turned off? I use the adapter plate shown below, it has a power switch to turn off and on the power and I always power it off before connecting or disconnecting any of the cables.

[Hangs4Fun]

3 hours ago, herein2020 said:

Had no idea this could happen, I power my monitor with a dummy battery and v mount plate adapter as well. Is this still possible even if the v-mount plate is turned off? I use the adapter plate shown below, it has a power switch to turn off and on the power and I always power it off before connecting or disconnecting any of the cables.

That is a nice feature.  If there is no voltage flowing, then the circuit in question is dead.

Most systems don't have that switch option. 

I had posted an easy to remember "you always start and end with power" in your case you are doing that by disabling the power source.

Also, remember this was more a possibility on SDI 6G/12G because the BNC cable could have a proceeding positive that touched before the ground completing the circuit through SGI 😮   This has been reported to happen with HDMI solutions, particularly with the faster HDMI 2.0 and 2.1 (that new 2.1 spec is crazy fast at 48 Gbps).  Most likely the gold connections were a tad higher for positive and/or neg had oxidation or lint or something, allowing postive to touch first.  In that scenario if you have a powered circuit to both your camera and recorder from the same power source, your hdmi in that scenario can complete the circuit.  Many times it can happen quick enough that the higher currents in the battery circuit don't spend enough time in hdmi or sdi to do damage, but in other cases it can fry the hdmi or sdi circuit (they just weren't meant for those levels of currents).

All that being said, if you use good quality cables, V Mount plates, C Mount Battery, etc. you are less likely to experience an issue.  But if you just follow a good workflow when operating your camera, you can avoid this issue all together.  Always start and end with power.  Get your power circuits in place and then add input/output.  Before shutting down remove all input/output, then disconnect power.  The important thing is to keep that power circuit in place to keep the voltage and current in the right places and using the correct grounds.

[BenEricson]

I setup my Sony F3 and the BM Video Assist to be powered from the same SWIT sony mount battery. I used this setup for a few years with no issues.

[Hangs4Fun]

34 minutes ago, BenEricson said:

I setup my Sony F3 and the BM Video Assist to be powered from the same SWIT sony mount battery. I used this setup for a few years with no issues.

yep, same here.  Good quality shielded cables and components.  I think the problem comes out with poorer quality cables.

[herein2020]

4 hours ago, Hangs4Fun said:

That is a nice feature.  If there is no voltage flowing, then the circuit in question is dead.

Most systems don't have that switch option. 

I had posted an easy to remember "you always start and end with power" in your case you are doing that by disabling the power source.

Also, remember this was more a possibility on SDI 6G/12G because the BNC cable could have a proceeding positive that touched before the ground completing the circuit through SGI 😮   This has been reported to happen with HDMI solutions, particularly with the faster HDMI 2.0 and 2.1 (that new 2.1 spec is crazy fast at 48 Gbps).  Most likely the gold connections were a tad higher for positive and/or neg had oxidation or lint or something, allowing postive to touch first.  In that scenario if you have a powered circuit to both your camera and recorder from the same power source, your hdmi in that scenario can complete the circuit.  Many times it can happen quick enough that the higher currents in the battery circuit don't spend enough time in hdmi or sdi to do damage, but in other cases it can fry the hdmi or sdi circuit (they just weren't meant for those levels of currents).

All that being said, if you use good quality cables, V Mount plates, C Mount Battery, etc. you are less likely to experience an issue.  But if you just follow a good workflow when operating your camera, you can avoid this issue all together.  Always start and end with power.  Get your power circuits in place and then add input/output.  Before shutting down remove all input/output, then disconnect power.  The important thing is to keep that power circuit in place to keep the voltage and current in the right places and using the correct grounds.

That's good to know, I've worked with electronics and IT equipment for many years and the first rule of thumb was to always remove power before connecting or disconnecting anything, so when I got my adapter plate I made sure it had a power button. The part I wasn't sure about was if there were any high capacity capacitors anywhere in the circuit that could still cause problems after the power was removed. I used to mod cars with custom audio systems and those audio caps could fry anything they touched weeks after the power was removed.

Of course now my concern is someone accidentally pulling out the HDMI cable while everything is powered on, I'm paranoid enough that I may still use a dedicated battery for my monitor. I've got about $20K into my C200 so I'm a little more paranoid than if it were something smaller.

[Hangs4Fun]

4 hours ago, herein2020 said:

That's good to know, I've worked with electronics and IT equipment for many years and the first rule of thumb was to always remove power before connecting or disconnecting anything, so when I got my adapter plate I made sure it had a power button. The part I wasn't sure about was if there were any high capacity capacitors anywhere in the circuit that could still cause problems after the power was removed. I used to mod cars with custom audio systems and those audio caps could fry anything they touched weeks after the power was removed.

Of course now my concern is someone accidentally pulling out the HDMI cable while everything is powered on, I'm paranoid enough that I may still use a dedicated battery for my monitor. I've got about $20K into my C200 so I'm a little more paranoid than if it were something smaller.

exactly the same here on electronics and IT equipment (almost 30 years now paying the mortgage with that stuff).  As they push more voltage out the SDI and HDMI ports, there is a growing chance of voltage going an unintended path.  But seriously  with good quality cables, components, and process, you are fine.  You have $20k in your C200 setup, so I'm sure you take operating it seriously.  I think those that are going to see a problem don't put much thought into plugging and unplugging, and use the cheapest parts that can "do the job".  It's a little harder for this to happen with HDMI, but easier with SDI 6G and 12G.  In high speed SDI 12G, I saw my first Galvanic video and ground path isolator.  This little device is around $400 (supposedly you can still get 12G speed, but not so sure though), thing was so small, was easy to leave attached to the cable.  I just saw an article describing a Lentequip Safetap, but at around $150 and some DIY work,  seems a bit much, but probably smart if you rent your gear out (which are the folks I have been trying to help with this issue).  For those of us that own and operate our own gear, we are going to take care of that investment.  

I think the reason you and I didn't see this with electronics and IT equipment, is because that equipment has true grounded wiring (on a camera rig it's self contained), is AC based, and better circuit isolation.  This potential issue is different.  You have 2 pieces of gear tapping into the same capacity source AND enter in a 3rd piece that connects between them, that is using more and more electricity lately (as SGI and HDMI get faster), yet still no where near the current levels of the 2 main pieces.  It would be like having a pc sized UPS powering 2 servers (with all of them only connected to each other with no true earth bound ground).  Now connect them together with 10Gbps or higher ethernet cable.  You now have a similar scenario.  Though, it is possible that circuitry in servers does a better job at isolating.  

[herein2020]

36 minutes ago, Hangs4Fun said:

exactly the same here on electronics and IT equipment (almost 30 years now paying the mortgage with that stuff).  As they push more voltage out the SDI and HDMI ports, there is a growing chance of voltage going an unintended path.  But seriously  with good quality cables, components, and process, you are fine.  You have $20k in your C200 setup, so I'm sure you take operating it seriously.  I think those that are going to see a problem don't put much thought into plugging and unplugging, and use the cheapest parts that can "do the job".  It's a little harder for this to happen with HDMI, but easier with SDI 6G and 12G.  In high speed SDI 12G, I saw my first Galvanic video and ground path isolator.  This little device is around $400 (supposedly you can still get 12G speed, but not so sure though), thing was so small, was easy to leave attached to the cable.  I just saw an article describing a Lentequip Safetap, but at around $150 and some DIY work,  seems a bit much, but probably smart if you rent your gear out (which are the folks I have been trying to help with this issue).  For those of us that own and operate our own gear, we are going to take care of that investment.  

I think the reason you and I didn't see this with electronics and IT equipment, is because that equipment has true grounded wiring (on a camera rig it's self contained), is AC based, and better circuit isolation.  This potential issue is different.  You have 2 pieces of gear tapping into the same capacity source AND enter in a 3rd piece that connects between them, that is using more and more electricity lately (as SGI and HDMI get faster), yet still no where near the current levels of the 2 main pieces.  It would be like having a pc sized UPS powering 2 servers (with all of them only connected to each other with no true earth bound ground).  Now connect them together with 10Gbps or higher ethernet cable.  You now have a similar scenario.  Though, it is possible that circuitry in servers does a better job at isolating.  

Yes that makes sense, that's the same reason why I only use OEM batteries...why try to save $20 on a battery in a $4K camera? It makes no sense when people get cheap parts for expensive gear; or the endless iPhone chargers with the cheap cables that can fry the iPhone port, the chargers die within weeks, and there's been cases where cars and houses have caught on fire, just to save a few $$ vs the OEM gear. 

All of my power related accessories (charger, v-mount adapter plate, v-mount battery) is bebob and so far its been great: http://bebob.de/en/v-mount.html the battery is so expensive I still only have one, but that one can power the camera and monitor for around 6hrs nonstop.

I did do a lot of research before I ordered the accessories for the C200 and only got the top of the line gear for it especially in the power and cabling departments; the only thing I don't trust is the dummy battery cable, I couldn't find one that wasn't a cheap mod from China.

I've been in the IT/electronics field for around 20yrs myself, I still remember using ESD bags and grounding straps to insert circuit cards and oscopes to check waveforms for signal noise and circuit issues...the days before electronics became disposable. That was so long ago I couldn't even turn on an oscope let alone know what I'm looking at these days.

[Hangs4Fun]

BeBob is really good, expensive but you have a workhorse that will give you every bit of what the sticker says. 

I'm building out my A7SIII rig, and went with the FxLion NANO TWO.  One it is small AF, and two it has USB-C with PD.  My plan is to actually run my A7SIII on it's Z100 battery, and at the same time charging it through it's USB-C PD port (the A7SIII supports charging the battery while also using it).  And for the first time, thanks to PD, you can charge the battery faster than it can use the battery.  This allows for me to swap Z Mount batteries without disruption to recording.

I also plan on recording out to my Ninja V sometimes 16bit RAW out (to 12bit ProRes RAW) others good ole 10bit 4:2:2 ProRes HQ.  What about battery swaps with that?  Well, thanks to Atomos buying TCS (makers of UltraSync line of timecode devices), they have a new AtomX module I just picked up this week called the AtomX Sync.  It provides Genlock timecode as master or slave with an RF and Bluetooth wireless network.  Best part is the timecode is baked into the media files, so none of the BS post work of converting LTC footage.  OK so what the heck does timecode have to do with batteries??  Well, the Sync module ALSO includes a small capacitor (aka battery), so that you have a good 5mins you can continue using your Ninja V monitor and recorder while you swap batteries.

So no disruption of recording locally and/or externally, because both the camera and the Ninja V will keep going while I swap V Mount batteries 🙂    I'm pretty proud of this setup, haven't heard anyone else doing it, as all of the pieces needed to do it are so new.  Hope to produce a few videos on it as soon as my A7SIII is in my hands.  I'm also doing some other cool stuff with my rig setup for quick change outs to go between cage/top handle only B Roll to Gimball to shoulder mount to tripod and back and forth.  

[LightShooter]

8 minutes ago, Hangs4Fun said:

BeBob is really good, expensive but you have a workhorse that will give you every bit of what the sticker says. 

I'm building out my A7SIII rig, and went with the FxLion NANO TWO.  One it is small AF, and two it has USB-C with PD.  My plan is to actually run my A7SIII on it's Z100 battery, and at the same time charging it through it's USB-C PD port (the A7SIII supports charging the battery while also using it).  And for the first time, thanks to PD, you can charge the battery faster than it can use the battery.  This allows for me to swap Z Mount batteries without disruption to recording.

I also plan on recording out to my Ninja V sometimes 16bit RAW out (to 12bit ProRes RAW) others good ole 10bit 4:2:2 ProRes HQ.  What about battery swaps with that?  Well, thanks to Atomos buying TCS (makers of UltraSync line of timecode devices), they have a new AtomX module I just picked up this week called the AtomX Sync.  It provides Genlock timecode as master or slave with an RF and Bluetooth wireless network.  Best part is the timecode is baked into the media files, so none of the BS post work of converting LTC footage.  OK so what the heck does timecode have to do with batteries??  Well, the Sync module ALSO includes a small capacitor (aka battery), so that you have a good 5mins you can continue using your Ninja V monitor and recorder while you swap batteries.

So no disruption of recording locally and/or externally, because both the camera and the Ninja V will keep going while I swap V Mount batteries 🙂    I'm pretty proud of this setup, haven't heard anyone else doing it, as all of the pieces needed to do it are so new.  Hope to produce a few videos on it as soon as my A7SIII is in my hands.  I'm also doing some other cool stuff with my rig setup for quick change outs to go between cage/top handle only B Roll to Gimball to shoulder mount to tripod and back and forth.  

I think this would solve the issues in this thread too, right?  Since the camera wouldn't be getting its power from the V Mount battery directly like with a dummy battery?

[Hangs4Fun]

Just now, LightShooter said:

I think this would solve the issues in this thread too, right?  Since the camera wouldn't be getting its power from the V Mount battery directly like with a dummy battery?

yes, it should.  But now that you mention it, let me think about it.  I may need to call up my ole college professor and run it by him.  Great point!

[Glauco]

I have a side, less electronic related question.

Powering ninjaV from Fxlion Vmount with dummy battery, the Atomos can’t determine when the battery is low (it works with 8,4v nominal voltage) so suddenly simply shut down. 
Did someone experienced this and knows if there is a way to be warned before?

thanks for your attention

[Khenu]

Hi,

I don’t well understand this all, but am wondering if a ground loop could also be an issue if trying to power my camera and a follow focus system off the same V mount battery.  I’m also using a (small rig) v mount plate with an on and off switch, though while waiting for an 8 volt to 7 pin cable for my follow focus, I’m wondering if I could use the dtap from the battery directly (which has no on off switch) while using the dtap from the plate as well (I only have one dtap on my plate, but there is an 8 volt and two 12 volt dc outputs).  I guess I don’t know if the potential for ground Loop is unique to when HDMI/SDI is in the mix, or if it could also be an issue in powering a camera from dtap on plate and follow focus from same plate (with dc output) or from same battery (but not the plate with on off switch). directly using dtap.  I hope that makes sense!

Thanks,

KS