Updated 22/01/2024.
Sadly this is not an uncommon problem. Suddenly and seemingly for no apparent reason the SDI (or HDMI) output on your camera stops working. And this isn’t a new problem either, SDI and HDMI ports have been failing ever since they were first introduced. This issue affects all types of SDI and HDMI ports. But it is more likely with higher speed SDI ports such as 6G or 12G as they operate at higher frequencies and as a result the components used are more easily damaged as it is harder to protect them without degrading the high frequency performance.
Probably the most common cause of an SDI/HDMI port failure is the use of the now near ubiquitous D-Tap cable to power accessories connected to the camera. The D-Tap connector is sadly shockingly crudely designed. Not only is it possible to plug in many of the cheaper ones the wrong way around but with a standard D-Tap plug there is no mechanism to ensure that the negative or “ground” connection of the D-Tap cable makes or breaks before the live connection. There is a however a special but much more expensive D-Tap connector available that includes electronic protection against this very issue (although a great product, even these cannot totally provide protection from a poor ground connection) – see: https://lentequip.com/products/safetap
Imagine for a moment you are using a monitor that’s connected to your cameras SDI or HDMI port. You are powering the monitor via the D-Tap on the cameras battery as you always do and everything is working just fine. Then the battery has to be changed. To change the battery you have to unplug the D-Tap cable and as you pull the D-Tap out, the ground pin disconnects fractionally before the live pin. During that extremely brief moment there is still positive power going to the monitor but because the ground on the D-Tap is now disconnected the only ground route back to the battery becomes via the SDI/HDMI cable and back through the camera. For a fraction of a second the SDI/HDMI cable becomes the power cable and that power surge blows the SDI/HDMI driver chip or damages the cameras motherboard.
After you have completed the battery swap, you turn everything back on and at first all appears good, but now you can’t get the SDI or HDMI output to work. There’s no smoke, no burning smells, no obvious damage as it all happened in a tiny fraction of a second. The only symptom is a dead SDI or HDMI.
And it’s not only D-Tap cables that can cause problems. A lot of the cheap DC barrel connectors have a center positive terminal that can connect before the outer barrel makes a good connection. There are many connectors where the positive can make before the negative.
You can also have problems if the connection between the battery and the camera isn’t perfect. A D-Tap connected directly to the battery might represent an easier route for power to flow back to the battery if there is corrosion on the battery terminals or a loose batter plate or adapter.
It can also happen when powering the camera and monitor (or other SDI connected devices like a video transmitter or timecode box) via separate mains adapters. The power outputs of most of the small, modern, generally plastic bodied switch mode type power adapters and chargers are not connected to ground. They have a positive and negative terminal that “floats” above ground at some unknown voltage. Each power supplies negative rail may be at a completely different voltage compared to ground. So again an SDI or HDMI cable connected between two devices, powered by different power supplies will act as the ground between them and power may briefly flow down the SDI cable as the SDI cables ground brings both power supply negative rails to the same common voltage. Failures this way are much less common, but they do still occur.
Sadly this is not an uncommon problem. Suddenly and seemingly for no apparent reason the SDI (or HDMI) output on your camera stops working. And this isn’t a new problem either, SDI and HDMI ports have been failing ever since they were first introduced. This issue affects all types of SDI and HDMI ports. But it is more likely with higher speed SDI ports such as 6G or 12G as they operate at higher frequencies and as a result the components used are more easily damaged as it is harder to protect them without degrading the high frequency performance.
Probably the most common cause of an SDI/HDMI port failure is the use of the now near ubiquitous D-Tap cable to power accessories connected to the camera. The D-Tap connector is sadly shockingly crudely designed. Not only is it possible to plug in many of the cheaper ones the wrong way around but with a standard D-Tap plug there is no mechanism to ensure that the negative or “ground” connection of the D-Tap cable makes or breaks before the live connection. There is a however a special but much more expensive D-Tap connector available that includes electronic protection against this very issue (although a great product, even these cannot totally provide protection from a poor ground connection) – see: https://lentequip.com/products/safetap
Imagine for a moment you are using a monitor that’s connected to your cameras SDI or HDMI port. You are powering the monitor via the D-Tap on the cameras battery as you always do and everything is working just fine. Then the battery has to be changed. To change the battery you have to unplug the D-Tap cable and as you pull the D-Tap out, the ground pin disconnects fractionally before the live pin. During that extremely brief moment there is still positive power going to the monitor but because the ground on the D-Tap is now disconnected the only ground route back to the battery becomes via the SDI/HDMI cable and back through the camera. For a fraction of a second the SDI/HDMI cable becomes the power cable and that power surge blows the SDI/HDMI driver chip or damages the cameras motherboard.
After you have completed the battery swap, you turn everything back on and at first all appears good, but now you can’t get the SDI or HDMI output to work. There’s no smoke, no burning smells, no obvious damage as it all happened in a tiny fraction of a second. The only symptom is a dead SDI or HDMI.
And it’s not only D-Tap cables that can cause problems. A lot of the cheap DC barrel connectors have a center positive terminal that can connect before the outer barrel makes a good connection. There are many connectors where the positive can make before the negative.
You can also have problems if the connection between the battery and the camera isn’t perfect. A D-Tap connected directly to the battery might represent an easier route for power to flow back to the battery if there is corrosion on the battery terminals or a loose batter plate or adapter.
It can also happen when powering the camera and monitor (or other SDI connected devices like a video transmitter or timecode box) via separate mains adapters. The power outputs of most of the small, modern, generally plastic bodied switch mode type power adapters and chargers are not connected to ground. They have a positive and negative terminal that “floats” above ground at some unknown voltage. Each power supplies negative rail may be at a completely different voltage compared to ground. So again an SDI or HDMI cable connected between two devices, powered by different power supplies will act as the ground between them and power may briefly flow down the SDI cable as the SDI cables ground brings both power supply negative rails to the same common voltage. Failures this way are much less common, but they do still occur.
For these reasons you should always connect all your power supplies, power cables, especially D-Tap or other DC power cables first. Avoid using adapters between the battery and the camera as each adapter plate is another possible cause of trouble.
Then while everything remains switched off the very last thing to connect should be the SDI or HDMI cables. Only when everything is connected should you turn anything on. But beware – there is a myth that turning cameras and monitors off before plugging or unplugging is enough to stop this issue. This simply isn’t true because power is fed to the monitor and camera even when they are switched off so power loops and surges can still occur.
If unplugging or re-plugging a monitor (or anything else for that matter) turn everything off first. Do not connect or disconnect anything while any of the equipment is on. Although the greatest moment of risk is the moment you connect or disconnect any power cables such as when swapping a battery where you are using a D-Tap to power any accessories.
Then while everything remains switched off the very last thing to connect should be the SDI or HDMI cables. Only when everything is connected should you turn anything on. But beware – there is a myth that turning cameras and monitors off before plugging or unplugging is enough to stop this issue. This simply isn’t true because power is fed to the monitor and camera even when they are switched off so power loops and surges can still occur.
If unplugging or re-plugging a monitor (or anything else for that matter) turn everything off first. Do not connect or disconnect anything while any of the equipment is on. Although the greatest moment of risk is the moment you connect or disconnect any power cables such as when swapping a battery where you are using a D-Tap to power any accessories.
So, if changing batteries, switch EVERYTHING off first, then disconnect your SDI or HDMI cables before disconnecting the D-Tap or other power cables. Seriously – you need to do this, disconnect the SDI or HDMI before changing the battery if the D-Tap cable has to be unplugged from the battery. Things are a quite a bit safer if any D-Tap cables are connected directly to the camera or a power plate that remains connected to the camera as this way you can change the battery without needing to unplug the D-Tap cables and this does reduce the risk of issues.
Also inspect your cables regularly, check for damage to the pins and the cable, if you suspect that a cable isn’t perfect – throw it away, don’t take the risk. I’ve seen plenty of examples of D-Tap cables where one of the wires has broken off the connector pins.
A great safety check is to turn on your monitor immediately after connecting the power, but before connecting any SDI or HDMI cables. If the monitor comes on OK, this is evidence that the power is correctly connected. Then you can connect the SDI or HDMI cable. However, while a really good idea, this only indicates that there is some power to the monitor, it does not ensure that the ground connection is 100% OK.
Also inspect your cables regularly, check for damage to the pins and the cable, if you suspect that a cable isn’t perfect – throw it away, don’t take the risk. I’ve seen plenty of examples of D-Tap cables where one of the wires has broken off the connector pins.
A great safety check is to turn on your monitor immediately after connecting the power, but before connecting any SDI or HDMI cables. If the monitor comes on OK, this is evidence that the power is correctly connected. Then you can connect the SDI or HDMI cable. However, while a really good idea, this only indicates that there is some power to the monitor, it does not ensure that the ground connection is 100% OK.
The reason Arri talk about shielded power cables is because most shielded power cables use connectors such as Lemo or Hirose where the body of the connector is grounded to the cable shield. This helps ensure that when plugging the power cable in it is the ground connection that is made first and the power connection after. Then when unplugging the power breaks first and ground after. When using properly constructed shielded power cables with Lemo or Hirose connectors it is much less likely that these issues will occur (but not impossible).
Is this an SDI/HDMI fault?
No, not really. The fault lies in the use of power cables that allow the power to make before the ground or the ground to break before the power. A badly designed power connector often made as cheaply as possible. D-Tap was originally designed to be used to be used with high power video lights, it wasn’t designed to be used with delicate monitors and the design will allow it to be plugged in the wrong way around if you force it.
Additionally it could be user error. I know I’m guilty of rushing to change a battery and pulling a D-Tap connector without first disconnecting the SDI on many occasions, but so far I’ve mostly gotten away with it (I have blown an SDI on one of my Convergent Design Odysseys).
If you are working with an assistant or as part of a larger crew do make sure that everyone on set knows not to plug or unplug power cables or SDI cables without checking that it’s OK to do so – and always unplug the SDI/HDMI before disconnecting or removing anything else.
If you are working with an assistant or as part of a larger crew do make sure that everyone on set knows not to plug or unplug power cables or SDI cables without checking that it’s OK to do so – and always unplug the SDI/HDMI before disconnecting or removing anything else.
How many of us have set up a camera, powered it up, got a picture in the viewfinder and then plugged in the monitor via an SDI or HDMI cable? Don’t do it! Plug and unplug in the right order – connect ALL power cables and power supplies first. Check power is going to the camera and check power is going to the monitor by turning them on, then finally plug in the SDI. When removing a battery, unplug the SDI/HDMI, power down the camera and only then remove the D-Tap from the battery.