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Arri WCU3 wireless system and interference


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#1 Adam Eden

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Posted 11 June 2011 - 03:30 AM

Hi
I have the new Arri WCU3 wireless focus and iris unit. I have a Archer 2SE sled and when I am flying a RED, i need to use a decimator to convert the HDSDI to composite video and patch that into the composite steadicam monitor.

The problem is that every time you turn the focus wheel on the remote you get really big interference lines on the steadicam monitor making it really difficult to frame.

Any ideas?

And yes I have tried different channels on the Arri rig.
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#2 Alfeo Dixon SOC

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Posted 11 June 2011 - 03:08 PM

Arri WCU3... Archer 2SE sled... i need to use a decimator to convert the HDSDI to composite video and patch that into the composite steadicam monitor.

The problem is that every time you turn the focus wheel on the remote you get really big interference lines on the steadicam monitorAny ideas?

Sounds like you many be having a grounding issue or a termination problem. What way are you powering your WCU and your decimator? I'm not very knowledgable about termination, but I do know it could be a culprit of SD...

Call the guys over at Tiffen on Monday morning.
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#3 thomas-english

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Posted 11 June 2011 - 04:29 PM

Its probably not an interference line but a power issue. Power dropping off to your Decimator because the LCS is taking it all.

Try running the LCS off the cameras D-Tap.
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#4 Adam Eden

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Posted 11 June 2011 - 07:39 PM

The decimator is getting power from RED camera, and the ARRI is getting power from the DTAP.

The RED is getting power from the Sled.

Even if I power the RED from its own battery, Decimator from sled, and the ARRI WCU from the DTAP it is still there. Arri wont help so It seems like an RF Problem,

Its also interferes with my IDX HDSDI Cam wave. VERY ANNOYING!!

Maybe it is a power problem.
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#5 William Demeritt

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Posted 11 June 2011 - 08:45 PM

Does the problem have any relation to the hand units distance from the receiver?

You can probably isolate it if it is an rf issue by running camera off block battery, power Decimator off the block or AC, use the Decimator to send the image to another off-sled monitor (powered off AC or whatever). Power the Arri separately somewhere nearby and try using the hand unit. Since the camera's power, grounding etc is completely separate from the Arri system, you'll know any distortion in image must be related to the RF.
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#6 James Davis

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Posted 12 June 2011 - 07:00 PM

I would be pretty surprised if it was a power issue, I have a slightly modified archer one which powers a Red with Preston and camwave, all off of a couple of red bricks at the bottom, and I used to run a redbyte via an XLR splitter running out of the accessory power at the front of the topstage (until I had a HD monitor fitted and the topstage converted to run HD-SDI).
I never had any issues personally, however I have never used the Arri LCS before so can't comment on that particular bit of kit.
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#7 Brian Freesh

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Posted 12 June 2011 - 07:44 PM

James, all that is well and good until something fails. It happens. If it's a power issue I the assumption should be that something is wrong with his rig, not with Archer 2s as a whole.

I have an identical problem right now with my rig when I have high amp spikes. The current draw spikes on the LCS (and all powered focus devices) when the motor is turning, so it could be a similar problem. OTOH, I'm surprised it's happening when the only things the sled is powering are the decimator and the monitor. Will's test sounds like a great idea.
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#8 James Davis

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Posted 12 June 2011 - 08:10 PM

I certainly agree that it's never a bad idea to run tests, was just saying I would be pretty surprised if it was a power issue as I know the set-up is pretty similar to the Archer 1 with regards to cables/connections etc, and by power I meant a lack of it. Obviously not accounting for minor faults in the rig etc, which by the sounds of it, Wills test would help give a more definitive answer here than all of us just giving our opinions ;)
There was no insinuation on my part that there was anything wrong with Archer 2's in general if anything it was more of a statement about how my sled is not so different from his, and how my set-up is very similar.
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#9 Brian Freesh

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Posted 12 June 2011 - 10:09 PM

Sorry, James, I guess I was a bit vague. Typing fast and all that...

I was agreeing that your set-ups are similar, just pointing out that there could still very well be something wrong with his rig. Even if your set-up was identical and it worked fine, that wouldn't help Adam, who may have an electronics issue inside of his own rig.

Hope that clears it up (knowing me, likely not)
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#10 William Demeritt

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Posted 13 June 2011 - 02:26 AM

James: also worth trying out is try other BNC cables, make sure you have a properly shielded signal coming into the decimator?
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#11 thomas-english

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Posted 13 June 2011 - 02:40 AM

Is your decimator at the top or the bottom of your rig?
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#12 Adam Eden

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Posted 13 June 2011 - 06:28 AM

My decimator is screwed onto the top cheese plate of my RED ONE.

The interference lines are worse when the motors are moving..

I am shooting with it tomorrow so I will try a few different setups. I was thinking of sticking the decimator on the back of the steadicam monitor with some double sided tape
and powering it off the sled.

The decimator is getting powered from the 4pin lemo off the RED currently.

Lemac are making some more cables for me, but I might see if Brett from Tiffen can do anything.

I am how ever enrolled in the Garret Brown steadicam course next month is Sydney, Australia so if I haven't figured it out by then
i am sure the master could!!

I am really looking forward to this course as i have only been shooting steadicam for a year now even though I have been a DOP for nearly 20years now.

Thanks guys for your input so far and I will let you know how I go.
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#13 Alfeo Dixon SOC

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Posted 13 June 2011 - 10:23 AM

The decimator is getting power from RED camera, and the ARRI is getting power from the DTAP.

The RED is getting power from the Sled.

Even if I power the RED from its own battery, Decimator from sled, and the ARRI WCU from the DTAP it is still there.

Its also interferes with my IDX HDSDI Cam wave. VERY ANNOYING!!

1) RED to Decimator is a custom cable... did you also customize your connector on the Decimator?
2) ARRI WCU is powered from what DTAP? If it's getting power from your sleds battery mount, then that is the source that powers the RED and the Decimator. Its all connected.

Williams test is your best friend... If clean, then track down the culprit.

First try powering the Decimator using your cable to the camera. That will tell you if its your cable and/or the RED camera. Eventually get back to your original setup to find what part of the puzzle is causing the issue...

The decimator is getting powered from the 4pin lemo off the RED currently.

My bet is on this cable



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#14 brett.mayfield

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Posted 30 June 2011 - 11:46 AM

While I havent used the ARRI WCU I do fly an Archer 2 with the CVolution and a AJA downconverter for my on-board monitor.
Try attaching your decimater to the bottom of the rig (make sure you place it such that your knees wont knock into protruding cables) and run it off of the sled dtap. I would put the ARRI UMC under the lens and power it through the lemo on the front of the sled. I fly it with the camwave sandwiched between the red brick and the battery plate. This way I have distance between anything thats transmitting or receiving signals. They only interruptions I have run into is some slight choppiness in my SD feed if Im being rough with the flying. Maybe youve already tried this strategy, but it seems to be working for my setups.
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#15 thomas-english

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Posted 07 July 2011 - 02:50 AM

The 4 pin power out on the red is a tool of lasr resort.

If your powering your LCS off the d tap from the red brick when u turn the motor your dropping the pwer to the camera and messing with the power to your decimator.

I would be so immensely surprised if this was an rf issue

i thought the c motion was interfering with my decimator as it turns out ive deceloped a dry joint on my decimator and now im onto the spare.
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