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Paralinx fried by Alexa


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#1 Matias Mesa

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Posted 23 October 2015 - 06:19 AM

Hi All.

 

Trying to find an answer to what happened yesterday:

 

Alexa XT was powered by IDX Batteries, Paralinx Arrow X was power through D-tap on camera. When the first AC wanted to hot swap the AB in order not to power down the camera, he plugged in the ARRI Power supply instead of a brick battery, as the result, my Paralinx fried instantly never to turn on again. Does anyone have this happened before or have an explanation to what happened?

 

Thanks

 

 

Matias


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#2 William Demeritt

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Posted 23 October 2015 - 11:42 AM

I don't think we ever got a real, reliable explanation, but Brian Freesh and I were able to recreate something VERY similar with a CineLive sled and killing a Teradek Bolt. 

 

 

I believe this has to do with the Alexa having a common ground for the SDI video and power system of the Alexa? Not entirely sure, I'm thinking an engineer can explain. However, the issue always seems to have these characteristics: camera powered in 24v mode, video device powered by 12v battery (either within the 24v series or 12v battery outside), and the video device connected via SDI. Here's a video illustrating the SDI grounding carrying power. 

 

 

Basically, any devices that aren't protected from voltage over the SDI ground (chassis) get damaged. It fried a Teradek Bolt, apparently fried your Paralinx Arrow X (assuming it's the SDI model), and a protection in the BlackMagic Hyperdeck Shuttle caused the battery to trip but the device didn't get fried.

 

I'm not sure if this brings you any closer to a definite answer. I think perhaps the newer devices have protection on the SDI ground, but I'm not positive. I haven't killed my IDX CW-3 yet, and I'm fairly certain I've powered it from a 12v source while the camera was in 24v off my sled (either from a battery in parallel OR from a separate battery [MON line] while camera gets 24v from CAM and AUX). 


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#3 Walter F. Rodriguez

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Posted 23 October 2015 - 12:09 PM

I have used a Teradek Bolt Pro SDI and Teradek Bolt 2000 SDI 2nd generation for the last three years and always power from Alexa 12v 2pin lemo. I have never had an issue.
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#4 Ken Nguyen

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Posted 23 October 2015 - 12:40 PM

Read this:

http://www.steadicam...243#entry113897

 

Cheers,

 

Ken Nguyen.


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#5 Matias Mesa

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Posted 23 October 2015 - 05:09 PM

I think it has to do with the Dtap power output and not from the Lemo 2. This is Arri Reply to my question:

 

Hi Matias,

 

Sorry to hear of your problem.

We do not supply D-tap function on Alexa via Anton Bauer or V-mount adapter plate.

 

You may have a  third party wired system.

1. Please connect 24volt via the 2 pin Fischer receptacle  

2. Check at the D-tap two pin female receptacle for 12 volt.

3. If the voltage measured is the same as the supplied voltage to the 2 pin Fischer receptacle, the system is wired to the 24v bus, this

    will damaged any accessories that operate between 7.5v to 17vdc such as your Arrow-X system. 

 

Please let us know your findings.

 

Kind regards

 

Roger


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#6 Victor Lazaro

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Posted 23 October 2015 - 06:12 PM

Yep Ken, this looks similar to what I had with the Arri 416. I was using it with a Bolt 300 MkII connected to the 3 pin lemos on the top of my Cine Live (maybe they added a ground protection on the MkII??)

What is the safe procedure in the meantime to accessorize the camera? Powering everything from the R/S port of the cam?

 

That isolation transformer is in my to buy list. http://www.bhphotovi...=Y&A=details&Q=

[edit] I also found this ground loop isolator that is way cheaper http://www.bhphotovi...nc_male_to.html


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#7 Matias Mesa

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Posted 23 October 2015 - 07:39 PM

Thanks, That will be on my list as well


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#8 Ken Nguyen

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Posted 24 October 2015 - 04:24 AM

Yep Ken, this looks similar to what I had with the Arri 416. I was using it with a Bolt 300 MkII connected to the 3 pin lemos on the top of my Cine Live (maybe they added a ground protection on the MkII??)

What is the safe procedure in the meantime to accessorize the camera? Powering everything from the R/S port of the cam?

 

That isolation transformer is in my to buy list. http://www.bhphotovi...=Y&A=details&Q=

[edit] I also found this ground loop isolator that is way cheaper http://www.bhphotovi...nc_male_to.html

 

The work-around is DO NOT POWER the camera before connect all video signals.

Connect all sdi connection first, then connect all power connections, then the batteries, then power your sled.  Power the camera last.

 

Turn camera off, then turn off the sled power before unplug sdi connections when wrap up.

This will prevent the ground loop surge which fries your equipment.

 

Cheers,

 

Ken Nguyen.


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#9 Brian Freesh

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Posted 24 October 2015 - 10:32 AM

Will, we did get a perfectly real explanation to the issue you mentioned, we created a loop that connected negative to negative on the batteries (ground loop?), and while the camera was protected, the Bolt was not. It's an issue that could come up on a non-cinelive sled, and also with any 24v series setup using 12v batteries on plates with ptaps or with built-in ptaps.  It could happen without a steadicam, but from what little info we have of the camera build and where things were plugged in and what happened there's no way to tell if it was the same issue.

 

FWIW, ALL cameras and video accessories use the power ground to ground the video signal.  You've never had a problem because you've never created the negative to negative loop. On your sled there is only one way to do this, on a cinelive there are 2 ways. And it will only happen when powering a 24v camera through the sled, and only when using the ptap on the AUX battery (2 of them on cinelive, 3 if using batts with built-in ptap) with a video accessory.  You can use that ptap with a non-video accessory, you can use the ptap when the sled is in 12v mode, you can use the ptap in 24v mode if you are not powering the camera through the sled.

 

EDIT: I don't know enough about what happened in Victor's situation.  My first guess is that his cables were wired to carry 24v and fried the bolt. I do not believe it is possible to cause the loop I am discussing through those lemos, but I also didn't even know it was a thing until I fried my decimator, which was after I'd fried Will's decimator doing the same thing on a different rig.  Neither of them were fed too much voltage, both were fried by the loop.


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#10 Joe Lawry

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Posted 25 October 2015 - 01:10 AM

Ive had ground loop issues with my Pro1 when running 24v, blowing up my decimator. Although stupidly I was powering the converter off the AUX port. Got a new 12v only cable made and now power off cam power.

 

Joe


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#11 William Demeritt

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Posted 25 October 2015 - 10:32 AM

Sorry, I didn't mean to confuse the issue, my showing those videos weren't to imply anything about the CineLive. In our testing, I remember we found a loop on the SDI ground, which sounds like the similar issue to Matias' setup. 

 

I'm pretty sure it works like this: 

 

ALEXA powered by 12V onboard

Video device powered 12V off the onboard PTAP

Video device connected to ALEXA via the SDI plug

 

Connect 24V power cable to Alexa, and the SDI line backfeeds 12V over the SDI ground. Unprotected devices get damaged. I need to ask some of my electrician friends, but I think it has something to do with voltage differential in a system that has 2 power supplies in 2 different voltage without a common ground. The 24v power supply has it's own 24v power and ground, and the Video device has a separate 12v power and ground (the onboard 12v battery). 

 

Safest method: power Video device from ALEXA 2-pin power cable through the body. I think the video manufacturers have been building in protections for this now, but I'm not entirely sure. 


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#12 John atkinson

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Posted 26 October 2015 - 06:38 AM

Hi All.

 

Trying to find an answer to what happened yesterday:

 

Alexa XT was powered by IDX Batteries, Paralinx Arrow X was power through D-tap on camera. When the first AC wanted to hot swap the AB in order not to power down the camera, he plugged in the ARRI Power supply instead of a brick battery, as the result, my Paralinx fried instantly never to turn on again. Does anyone have this happened before or have an explanation to what happened?

 

Thanks

 

 

Matias

 

Never plug any accessory in when camera is powered up.  Make all connections before adding power.


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#13 Jess Haas SOC

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Posted 26 October 2015 - 11:18 PM

My Teradek got fried on an Alexa as well. Some stuff was being moved around and I saw a spark between the BNC going to the lock-it box and the Alexa body and it fried the SDI line on the Teradek. I was using the 2pin lemo to power it. Nothing else was damaged.

 

-Jess


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#14 Ken Nguyen

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Posted 27 October 2015 - 12:58 AM

Beware of power Tereadek using non-Teradek 2pins lemo.

Teradek tech should be addressed this issue.

All of our accessory which powered by 2pins lemo are following standard wiring code.

pin1 is positive; pin 2 is negative.

 

Teradek is reversed.  Pin 1 is negative.

 

So, if you use 2pin-lemo cable, you will fry your device.

I was lucky, PRO has 3 circuit breakers to protect.

It popped out and saved my day.

That's when I found out Teradek Pin1 is negative.

Always bring along a voltmeter with you.

 

Cheers,

 

Ken Nguyen.


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#15 Afton Grant

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Posted 27 October 2015 - 06:58 AM

Apologies if I misunderstood what you were saying, Ken, but the most common standard IS to have pin 1 be the ground pin (negative).  On a majority of accessories, and electronics in general, pin 1 will be ground - regardless of number of pins.  There are a few exceptions, however (the Bartech comes to mind), so it's wise to always check.  


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