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Record Run Time Code Drift from camera to 788T via Zaxcom QRX - IFB


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Just got the Zaxcom up and running I am happy with the audio link but am having problems with record run time code.

The 788 is set to auto record and does get the trigger to start recording from the camera, but after recording for a couple of minutes the time code noticeably drifts by up to three seconds after say a ten minute take. Any ideas?

The other strange thing is that the trigger does not happen spontaneously with the camera getting up to speed so there is a two or three second delay behind the camera into record on the 788. The other thing is that when the camera is cut the 788 cuts and parks a couple of seconds behind the camera time code. My old system for time code transmitting via a sennheiser G3 and this is spot on with time code trigger, cut and sync so has anyone got any ideas about my Zaxcom problem? as I don't want to have to go back to having my G3 on the camera too, the whole idea of getting the Zaxcom it is all in one.

Many thanks

Sorry I have reposted my topic as it was in the wrong category!

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Hi Jack

Yes the frame rates are all set to 25fps on the camera, QRX, TRX900 and 788.

I just did another test and noticed that doing a visual count the camera, Qrx/Ifb and trx900 timecodes are all in sync, it's the Sound devices 788 that slipping out. Which would point at the output on the STA150, cable to the 788 or a setting on the 788 but I can't see anything obvious.

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Have you tried putting the camera in record, jam syncing the 788 then disconnecting and seeing how accurate the camera is? Take everything else out of the equation and start adding things once you are sure each thing is good.

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Hi Rich

Just tried that your suggestion and as I suspected like the old Sennheiser G3 system it stays spot on time code sync and turns over and cuts simultaneously with the camera. The only way i could do this test thought with record run was with the camera and 788 hard wired as when you unplug the time code lead the TC stops, so I also tried it on free run and disconnected the time code lead left it running for ten minutes at they appeared to be still in sync

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This test is on a Sony DSR570 that someone has lent me while I get the Zax fully up to speed. I noticed the problem thought on a Sony 750 which did exactly the same thing as this DSR570.

As I mentioned earlier the TC all sync's up with the screen on the camera, the screen on the QRX and the Screen on the TRX900 visually but when you look at the screen on the 788 that is where the drift is occurring. So all seems well until the it travels out of the STA150 to the 788. If I plug in my old G3 TC the problem is eliminated so I'm a bit lost, because that to me means the 788 is set up right.

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So I have tested:

free run coming from the camera via zaxcom to 788 sync drift.

record run coming form camera via zaxcom to 788 sync drift

free run from 788 via zaxcom to camera all in sync.

hard wired camera to 788 all in sync.

sennheiser g3 record run from camera via g3 to 788 all in sync.

Just wonder if I am missing something in the TRX900 menu?

Have you guys used your Zaxcom for record run auto record on a 788? as I know record run is rare now or to take a time code feed from a camera is rare now but if so has it all been in sync for you?

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There is a slight delay when the conversion of TC to zax IFB happens due to the processing overhead.

Is the drift consistent, or random in nature?

Are you eyeballing it, or having the camera record all the sources displays and comparing frame by frame off the footage?

Sent from my HoboPad

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whenever i need to be in auto record and wireless, i am only confident with my sennheiser G2.

i am not yet convinced that, unless you are quite close to camera, that the zaxnet output from a qrx could reliably trigger the auto record - thinking in terms of starting and stopping and giving solid signal throughout, rather than the valid point that Joel makes about the zaxnet processing delay.

only thing in the trx menu that can affect timecode is the timecode jam mode, which shouldnt affect drift, and the framerate setting in the normal menu.

and also the framerate page in the ifb menu on the qrx.

in the timecode jam menu on the 788 (press menu and hdd at the same time) you can check your timecode framerate. you might need some adapters, but you could try and see that your framerate is good all the way along your chain

- out of the camera

- out of the qrx

- out of the sta.

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Thanks for your replies.

Joel the timecode visually at the beginning of the take looks to be in sync, but drifts out as the take goes on so the longer the take the grater the drift.

Like you say rich I think I will be using my tried and tested G3 for auto trigger like I used with my old Audio Div 2000 link as the Zaxcom system is appearing to be unreliable which is disappointing.

All the way though the chain the timecode is spot on until it comes out of the sta150 and goes into the 788. As I mentioned above the Zaxcom seems fine for time of day TC which most of my work will be with signal camera probably as its not working to hard so maybe i will just use it for that.

Matt the frame rate for internal and external TC on the 788 are both at 25ND. The frame rate indicator on the main screen of the 788 is stable on not flashing @ 25 ND also. I have had that flash in the past on jobs where the TC coming in is not lining up with the TC set on the 788, so that does not seem to be the problem.

Thanks Guys

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