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.
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I had heard about the issue but now I finally understand it too. Thanks for explaining it so clearly. I bought one of those SafeTap connectors but could not decide which device should get the honor. Now I know, the EVF with the SDI should be protected with the SafeTap. Excellent!
RED suggests powering everything up before connecting the SDI. Some 3rd party monitors do not have on/off switches. In these cases, connecting the battery first implies the monitor is powered up before the SDI is made. “• While the power status of the monitor or SDI device does not matter, by powering up the monitor you are ensuring the device has been correctly grounded. Therefore, we suggest attaching power & then powering up before plugging the SDI into the camera.”
There is some merit to what Red suggest. But powering up the monitor before connecting the SDI only proves the monitor has some power. It does not guarantee that the negative rail of the monitor and camera are at the same potential, which is particularly a problem with independent power supplies. It may also be possible that the monitor can power up with a less than perfect ground connection. Plugging in the SDI cable will in these cases act as a ground strap and it’s normally better to ground everything prior to applying power or turning devices on.
Excellent information, much appreciated, Alistair. I currently connect my SmallHD 702 Touch to the Dtap out (on my IDX BPU camera batteries) using a perfect length coiled and very nice Kondor Blue D-tap to Sony L-series battery cable (see https://kondorblue.com/products/copy-of-d-tap-to-sony-a7siii-dummy-battery-np-fz100-cable). As far as you may know, does the Sony-L series connector that connects to my 702 Touch afford any sort of protection along the lines of how connectors such as Lemo or Hirose do, where the body of the connector is grounded to the cable shield? Am trying to avoid a soldering job, but certainly also to avoid SDI failure and repair! Thank you. Best, Tom
No, no protection and can suffer from the issues detailed above. If it’s D-Tap then it’s unprotected, doesn’t have a screen connection and can connect positive before negative. The ONLY exceptions are the much more expensive electronically protected “Safe-D-tap” cables and connectors.
Does HDMI have the same problems ?
Yes, but it is much less common as the way an HDMI cable works means there is less likelihood of the current in the ground wire inducing a voltage on the signal wires great enough to blow the drivers. But in the case of a very poor power ground if sufficient current flows through the HDMI ground it can damage the HDMI circuits.
Ok thanks ,so best to take then same precautions I guess
After following this thread I went and bought a hand full of SafeTap connectors. I noticed that they went down $10 in price per piece on Amazon. I thought I’d hand it on and mention it here.
Following Robyns comments (Hi Robyn!)- a hire company that I use reported some time ago, several such HDMI failures to their FS7’s.
Thanks for the SDI alert Alister-hopefully preventing
an easy mistake to make!
Bmj
When swapping batteries that only power the camera, there’s no need to disconnect the SDI cable right (red does agree with this)?
Would the same hold true if an accessory (let’s say a monitor) is powered by itsown battery, separate from the camera battery?
If the battery ONLY powers the camera and nothing else then there should be no need to disconnect the SDI, but this isn’t guaranteed and it certainly won’t do any harm to disconnect.
The main issue is where a single battery is powering the camera and accessories or different mains power supplies are powering the camera and accessories.
Interesting… I recently purchased a second-hand Fs5 with a faulty EVF for a very low price. (the previous owner supplied a Zacuto Z-Finder setup for the LCD and a shoulder mount kit) On testing the camera, I have found the SDI output to be inoperative (HDMI is OK) so I’m wondering if the EVF is driven from the SDI circuit board as the two are in very close proximity? The previous owner was happy to record internally but I need SDI out as I monitor & record from a Samurai Blade SSD device with a loupe.
I don’t know where the driver circuits are and whether they are interconnected. But with the HDMI working and SDI not I would suspect that this suggests the SDI driver is damaged. I assume you are aware that you can’t have SDI and HDMI at the same time.
Thank you for this insightful explanation! I still have one or two questions …
1. when changing the power cable or power source, is it correct to disconnect SDI/HDMI first. Is it enough to disconnect only one side of the cable or is it necessary to disconnect the cable on both sides?
2) It is often said that the problem does not occur when the devices connected by SDI/HDMI are powered by separate power sources. Is this true and why, is there a simple explanation?
3. is there a difference in the procedure between operation with battery and power supply?
You only need to disconnect one end of the cable, you are just breaking the possibility for the SDi cable to pass power between the camera and whatever it’s connected to.
Separate power sources are less likely to cause an issue, but it is still possible. The main issue is with a single power source and the SDI cable acting as a power cable between the single power source and other devices connected via the SDI cable.
With multiple power supplies it’s the same order.
Hi Alistair,
When you mention the issue arising when disconnecting the d-tap cable, is this literal?
For example if I am powering my monitor/teradek through a d-tap on a v-lock plate (such as on FX9s) and the cabling all remains in place, do I still need to follow the same procedure each time I change battery?
Thanks,
If the D-Tap cable is attached to a plate rather than the battery then there it is unlikely for the monitor ground to be interuppted during a battery change, so the risk is much lower and the cable can probably be left attached. But I think one of the issues with the FX9 is that the camera is actually partially isolated from the battery via the necessary 19.5V DC to DC converter. But the D-Taps on the adapter plate are directly connected to the battery and this has the potential to increase the risk of power flowing where you don’t want power flowing, especially if the DC plug makes anything less than a perfect connection..