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CRT Preventive Maintenance


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#1 Joseph Cruel

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Posted 04 August 2008 - 04:07 AM

Hi. I was wondering when would you know when to replace the CRT before it loses or sacrifices in image quality.

Is there a big difference between the Brimar CRT and the ITK millennium machine CRT. Has anyone had any experience with either and has done a comparison?
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#2 Stephen Williams

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Posted 04 August 2008 - 04:28 AM

Hi. I was wondering when would you know when to replace the CRT before it loses or sacrifices in image quality.

Is there a big difference between the Brimar CRT and the ITK millennium machine CRT. Has anyone had any experience with either and has done a comparison?


Hi,

I remember with Ursa telecines the tube would drop off after about 1000 hours. You need to save test frames to see the drop off, some facilities will run the tube on low beam current to try to make it last longer, unfortunately you just get noisy pictures from the start.
A good tube in an ITK Millennium can be fantastic, it's all down to maintenance & what the facility perceives as good enough.

Stephen
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#3 Joseph Cruel

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Posted 04 August 2008 - 05:19 AM

Hi,

I remember with Ursa telecines the tube would drop off after about 1000 hours. You need to save test frames to see the drop off, some facilities will run the tube on low beam current to try to make it last longer, unfortunately you just get noisy pictures from the start.
A good tube in an ITK Millennium can be fantastic, it's all down to maintenance & what the facility perceives as good enough.

Stephen


Hi Stephen,

Thanks for your prompt reply.

We have an ITK Millenium, and were actually thinking of having the CRT replaced soon. The hours are high and we are considering a replacement quite soon. We got two proposals, one for a Brimar CRT and the other from Thomson. Would you have any experience with either?

Cheers.

Joseph
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#4 Stephen Williams

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Posted 04 August 2008 - 07:06 AM

Hi Stephen,

Thanks for your prompt reply.

We have an ITK Millenium, and were actually thinking of having the CRT replaced soon. The hours are high and we are considering a replacement quite soon. We got two proposals, one for a Brimar CRT and the other from Thomson. Would you have any experience with either?

Cheers.

Joseph


Hi,

I always used the Brimer tubes, but that was a long time ago. I think you should ask the question on TIG, the telecine internet group.

Stephen
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#5 Joseph Cruel

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Posted 04 August 2008 - 08:56 AM

Hi,

I always used the Brimer tubes, but that was a long time ago. I think you should ask the question on TIG, the telecine internet group.

Stephen


Cheers mate.
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#6 Paul Bruening

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Posted 05 August 2008 - 09:19 PM

Hey Stephen,

I didn't realize that these tubes had so little life in them. 1,000 hours isn't very much. What's the very limit of usefulness in them? Can they plateau at a reasonable time and, then, still deliver useful results at a lower resolution for a longer time?

Could you cool them and get better results or longer life?
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#7 Richardson Leao

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Posted 06 August 2008 - 07:09 AM

Hey Stephen,

I didn't realize that these tubes had so little life in them. 1,000 hours isn't very much. What's the very limit of usefulness in them? Can they plateau at a reasonable time and, then, still deliver useful results at a lower resolution for a longer time?

Could you cool them and get better results or longer life?

Hi Guys,

sorry to hack into the thread but just a technical doubt I have, the CRT tube provides the light source for the scanning or what? Also, in a normal telecine (e.g. ursa), the frame is captured through what, a ccd sensor? Many thanks!!!
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#8 Robert Houllahan

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Posted 06 August 2008 - 09:36 AM

Hi Guys,

sorry to hack into the thread but just a technical doubt I have, the CRT tube provides the light source for the scanning or what? Also, in a normal telecine (e.g. ursa), the frame is captured through what, a ccd sensor? Many thanks!!!



The "patch" on the CRT is the light source for the scanner, the frame is captured by a set of three photomultiplier tubes one for each red, green and blue channel. Actually in a "flying spot" scanner such as a millenium or dsx the electron beam (the spot) is tracked at all times and the full bandwidth R,G,B signals are then combined the the framestore to make a full picture. This allows for optical zooms or rotation, etc by varying the shape of the patch on the crt. Modern crt scanners are capable of 4K scans and can provide some of the nicest looking scans if they are properly maintained. Most facilities will switch out the crt once or twice a year.

-Rob-
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#9 Stephen Williams

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Posted 06 August 2008 - 09:50 AM

Hey Stephen,

I didn't realize that these tubes had so little life in them. 1,000 hours isn't very much. What's the very limit of usefulness in them? Can they plateau at a reasonable time and, then, still deliver useful results at a lower resolution for a longer time?

Could you cool them and get better results or longer life?


Hi Paul,

You might be lucky & get a little more, it was the same for tune cameras. After a while they get burns, it's really down to what is good enough for you. As Robert says 1 or 2 tubes a year would be normal for a facility.

Stephen
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#10 John Sprung

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Posted 06 August 2008 - 01:17 PM

Burns were a big problem in the early days, especially if the same machine had to switch between super and academy, or three and four perf. For quite a while now they've had automatic compensation. Run the machine without film, tell its computer so, and it grabs the numbers it needs to scale the output to be completely neutral. Even with compensation, though, eventually the light output gets too low to use.



-- J.S.
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#11 Stephen Williams

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Posted 06 August 2008 - 01:34 PM

Burns were a big problem in the early days, especially if the same machine had to switch between super and academy, or three and four perf. For quite a while now they've had automatic compensation. Run the machine without film, tell its computer so, and it grabs the numbers it needs to scale the output to be completely neutral. Even with compensation, though, eventually the light output gets too low to use.



-- J.S.


Hi John,

I remember after 3 days of transfering S16 with a new tube, we switched to Academy and the S16 patch was very clear. We had to swop tubes back & forth, a real pain as you need at least 4 hours to line it up properly.

Stephen
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#12 Paul Bruening

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Posted 07 August 2008 - 08:51 PM

Hey Stephen,

I registered at TIG. I haven't heard back from 'da man. How often does he check his site? I guess, I qualify for inclusion since I have my own rig regardless of how dubious it is. What do you think?
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