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tse
Joined: 03 May 2006
Posts: 1005
Location: Sweatbucket, Fl.
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 Link Posted: Tue Jun 29, 2010 12:55 am Post subject: |
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I think you will see that properly charged magnets will not focus perfectly in the centrer if the h dynamic coil is not connected to the focus amp. The h focus current is cap coupled to the h dynamic coil. That means that the current goes equally positive and negative. So the center focus will not be perfect unless the h dynamic current is negative when the center of the screen is being swept. This applies to Marquee projectors.
Scott
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Tue Jun 29, 2010 1:37 am Post subject: |
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| Nashou66 wrote: | .....With good focus coils its obvious to see the focus ability compared to one that has weak magnets while not electronically connected.
Athanasios |
man, how did I miss this jewel. When and how did they start with "weak" magnets in the Marquee focus coils. I've never seen or had a problem with a weak magnet (or coil). This is definitely fresh for me.
I've changed out and have swapped in coils a many of time, but don't recall ever seeing or finding one that was weaker than the other.
say Curt, have you also seen this problem?
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1585
Location: Austin, TX
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| Link Posted: Tue Jun 29, 2010 1:42 am Post subject: |
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Not sure if it's been mentioned already? But if someone re-tubed the machine and didn't adjust the scheimpflug properly, that could cause a focus issue. If the lens plates are too far forward or too far back, you may not get good focus.
I'm not talking about up/down or right/left scheimpflug. But rather all three settings combined. I think AC's like to have 11/16"? Can't remember about the LC's. It may be the same?
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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| Link Posted: Tue Jun 29, 2010 1:45 am Post subject: |
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From another thread:
| Chuchuf wrote: | Focus Coil..........or a very very very bad CPC
When we were running some tube tests a few months ago, we found a bad focus coil that acted similar in the test Marquee chassis we were using which had been stored for a few years. Could not focus. Replaced coil and everything was OK. First one I have seen that was bad, so we know it can happen. We have see bad CPC's as well a few times.
Crud in the tube usually shows up as noise.
Terry |
Nashou
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Tom Bauerle to Andre Cuomo" Elliot Spitzer Screwed some Prostitutes, you screwed the Constitution" On his call to Cuomo to Resign!!!
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dvh99
Joined: 25 Dec 2009
Posts: 1955
Location: nederland
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| Link Posted: Tue Jun 29, 2010 1:55 am Post subject: |
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i think scott just means that by the design of the focus yokes (because of the design of the focus module) the center will focus less than the edges when not connected to the amp.
this is exactly what i saw, the center was blurry but the edges were better focussed.
well, maybe i am completely wrong and damnit brasil won thats a tough nut to crack.
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marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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dvh99
Joined: 25 Dec 2009
Posts: 1955
Location: nederland
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| Link Posted: Tue Jun 29, 2010 2:00 am Post subject: |
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hi eddie we were just discussing rough focus on the tube face.
i had no idea how well calibrated coils should look like when not connected to the amp and i didnt suspect the focus board to be bad cause it did adjust focus.
the only problem was of course that best focus was at 100 and that can never be good.
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marquee 9500ultra HD10L moome hdmi1.3 v3+ some mods.
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CZ Eddie
Joined: 23 Mar 2006
Posts: 1585
Location: Austin, TX
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| Link Posted: Tue Jun 29, 2010 3:16 am Post subject: |
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| dvh99 wrote: | ok focus board is bad tested it today, with my fgm focus was perfect at 45.
anyone have a spare focus board for sale?
i thought to get better focus with just the coils and no connection to the focus board. |
Oops, I missed this post. Glad to hear you got it figured out!!
I have a focus module on ebay. But it isn't for Ultras.
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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| Link Posted: Tue Jun 29, 2010 4:13 am Post subject: |
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| mp20748 wrote: | | Nashou66 wrote: | .....With good focus coils its obvious to see the focus ability compared to one that has weak magnets while not electronically connected.
Athanasios |
man, how did I miss this jewel. When and how did they start with "weak" magnets in the Marquee focus coils. I've never seen or had a problem with a weak magnet (or coil). This is definitely fresh for me.
I've changed out and have swapped in coils a many of time, but don't recall ever seeing or finding one that was weaker than the other.
say Curt, have you also seen this problem? |
Marquee Focus magnet Charger Discharger used by TSE to re-magnetize weak or out of spec marquee Coils.
Original thread
Nashou
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"The government can't control the economy without controlling the people" RR
One Smart Dog!!!
Tom Bauerle to Andre Cuomo" Elliot Spitzer Screwed some Prostitutes, you screwed the Constitution" On his call to Cuomo to Resign!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Tue Jun 29, 2010 10:56 am Post subject: |
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| Nashou66 wrote: |
Marquee Focus magnet Charger Discharger used by TSE to re-magnetize weak or out of spec marquee Coils.
Original thread
Nashou |
It's a good thing the coils have been de-magnetized or whatever before leaving the factory, and that would explain why I've not seen or had a problem with these coils.
And the explanation that Scott gave a few threads earlier further explains why I've not seen a problem if all is well with the focus drive circuit:
| tse wrote: | I think you will see that properly charged magnets will not focus perfectly in the centrer if the h dynamic coil is not connected to the focus amp. The h focus current is cap coupled to the h dynamic coil. That means that the current goes equally positive and negative. So the center focus will not be perfect unless the h dynamic current is negative when the center of the screen is being swept. This applies to Marquee projectors.
Scott |
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 18065
Location: Langley, BC
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| Link Posted: Tue Jun 29, 2010 2:23 pm Post subject: |
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| mp20748 wrote: |
say Curt, have you also seen this problem? |
I've seen it once on one coil. I too would have suspected the HVPS or focus board since all three tubes were affected at the same time. Having three bad focus coils in the same set would be insanely bad luck.
With the one bad one I had, the tube wouldn't focus, and the center focus setting was way down at 0 (or 100, I can't remember), and needed to go below/above that to get good focus. The R and B tubes were perfect, so I swapped focus coils and the green snapped right in.
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Nashou66
Joined: 12 Jan 2007
Posts: 12849
Location: West Seneca NY
TV/Projector: Marquee 8000, 8500 And a 9500LC RetroIV , 2 Longbow 8500 Ultras(2004!!)Hd145's , Ampro 3600, a G90!!
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| Link Posted: Tue Jun 29, 2010 2:38 pm Post subject: |
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| Curt Palme wrote: | | mp20748 wrote: |
say Curt, have you also seen this problem? |
I've seen it once on one coil. I too would have suspected the HVPS or focus board since all three tubes were affected at the same time. Having three bad focus coils in the same set would be insanely bad luck.
With the one bad one I had, the tube wouldn't focus, and the center focus setting was way down at 0 (or 100, I can't remember), and needed to go below/above that to get good focus. The R and B tubes were perfect, so I swapped focus coils and the green snapped right in. |
Yep, exactly what i said earlier.
And my bad coil does the same as what you described Curt.
Anyways he figured out it was the FGM, glad its working.
Athanasios
_________________
Don't blame your underwear for your crooked ass~ unknown Greek philosopher
"The government can't control the economy without controlling the people" RR
One Smart Dog!!!
Tom Bauerle to Andre Cuomo" Elliot Spitzer Screwed some Prostitutes, you screwed the Constitution" On his call to Cuomo to Resign!!!
Marquee High Performance Bellows now shipping!!
Marquee Modifications and Performance Enhancement
Marquee C-element and Bellow removal
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Wed Jun 30, 2010 12:31 am Post subject: |
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| Nashou66 wrote: | Ok Mikey, you keep thinking what you want and I'll know from my own experience what I learned.
I don't know what your problem is lately but I hope you work it out.
All the best.
Athanasios |
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Wed Jun 30, 2010 12:54 am Post subject: |
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| Curt Palme wrote: | | mp20748 wrote: |
say Curt, have you also seen this problem? |
I've seen it once on one coil. I too would have suspected the HVPS or focus board since all three tubes were affected at the same time. Having three bad focus coils in the same set would be insanely bad luck.
With the one bad one I had, the tube wouldn't focus, and the center focus setting was way down at 0 (or 100, I can't remember), and needed to go below/above that to get good focus. The R and B tubes were perfect, so I swapped focus coils and the green snapped right in. |
What you've described Curt, I've seen before. If you would have removed the cover from the coil, you would have noticed that one of the magnets (alnico) broke loose from the assembly. When one breaks loose, it throws off everything.
What I was referring to is a batch of coils having strength problems, or coils as mentioned being weak. That i've never seen, and it's not that I've seen everything, it's just that I've never seen that problem ever.
I've swapped out a many focus coil, to include, replacing a coil from a suspected weak coil with one that was new, and nothing different ever noticed between the two.
What I have noticed however, is a difference in the coils from one to the other that would put the best focus range showing different numbers. Not sure what that was all about, but between either coil I was able to get the exact same focus results. It's just that I had to move the focus range from one to the other.
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cmjohnson
Joined: 03 Apr 2006
Posts: 1677
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| Link Posted: Wed Jun 30, 2010 12:59 am Post subject: |
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Incidentally, if you've been doing any experiments with other kinds of focus coils (Frankenyoke candidates), you probably HAVE encountered "weak" magnets. The ones that have been found to be unsuitable for use in a Marquee due to poor focus ability may have high quality magnetic field shapes but they tend to be weaker than the stock Thomson yokes in terms of raw magnetic strength values.
THIS could be what Nashou was referring to.
Incidentally, if you take the Thomson yokes off a bunch of Marquees and throw them all in a box and move the box around and let the coils bang into each other and interact with each other magnetically, they WILL start to demagnetize each other. People don't realize it, but those coils should be carefully stored apart from each other and should have a steel keeper ring inserted in them to keep the magnetic field confined close to the coil to avoid demagnetizing outside influences.
All new focus coils are shipped from the factory in trays and every one of them comes with a keeper ring in it. Maybe Tse should grab a few and sell them to those of us who work on projectors regularly so we don't trash our extra focus coils.
CJ
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Wed Jun 30, 2010 1:07 am Post subject: |
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| cmjohnson wrote: | if you take the Thomson yokes off a bunch of Marquees and throw them all in a box and move the box around and let the coils bang into each other and interact with each other magnetically, they WILL start to demagnetize each other. People don't realize it, but those coils should be carefully stored apart from each other and should have a steel keeper ring inserted in them to keep the magnetic field confined close to the coil to avoid demagnetizing outside influences.
CJ |
I'm aware of this, and it's because of the magnet material (Alnico) they use. Improper storage as well as placing them near objects that can demagnetize them I'm aware of, but have not seen myself.
The question I raised here on this issue involves coils that are INSTALLED in the projector and mounted on the tubes -- how would they become demagnetized or effected in this manner?
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cmjohnson
Joined: 03 Apr 2006
Posts: 1677
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| Link Posted: Thu Jul 01, 2010 3:55 am Post subject: |
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I don't know. Stranger things have happened.
I know that VDC is very good about ensuring that all focus yokes are calibrated prior to installation but I think that other owners of the Marquee brand may have occasionally let uncalibrated yokes slip by.
Maybe someone was holding a bulk tape eraser up near the projector? 
I can only say that magnets do change strength with time. The rate can vary even between two identical magnets from the same lot and subjected to similar operating and storage conditions. Maybe it's a contamination issue in the magnetic alloy?
I'd theorize that if there's a lot of arcing going on in the projector, it could affect the permanent magnets in the focus coil. While a typical
arc is a low current event, it does generate SOME small magnetic field. If the arcing is consistent over a period of time, the cumulative effect MIGHT be enough to measurably change the magnet's strength.
I can't say how likely this is, but it may be vaguely within the realm of possibility if you close one eye and squint a little with the other.
CJ
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mp20748
Joined: 12 Sep 2006
Posts: 3147
Location: Camp Springs
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Link Posted: Thu Jul 01, 2010 10:29 pm Post subject: |
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| cmjohnson wrote: | I don't know. Stranger things have happened.
I know that VDC is very good about ensuring that all focus yokes are calibrated prior to installation but I think that other owners of the Marquee brand may have occasionally let uncalibrated yokes slip by.
Maybe someone was holding a bulk tape eraser up near the projector?
I can only say that magnets do change strength with time. The rate can vary even between two identical magnets from the same lot and subjected to similar operating and storage conditions. Maybe it's a contamination issue in the magnetic alloy?
I'd theorize that if there's a lot of arcing going on in the projector, it could affect the permanent magnets in the focus coil. While a typical
arc is a low current event, it does generate SOME small magnetic field. If the arcing is consistent over a period of time, the cumulative effect MIGHT be enough to measurably change the magnet's strength.
I can't say how likely this is, but it may be vaguely within the realm of possibility if you close one eye and squint a little with the other.
CJ |
I understand all that you're saying here, but until either VDC or the previous owners of the product has said the same or indicated that there has been incidents or case were the coils had to be replaced or charged, then I would agree with your theory here.
But in my experience with these coils over the years, I could never get anyone from Christie (Electrohome) or VDC to ever say at any time in any reported focus problem I've ever mentioned over the almost two decades of my experience with the projector, that it could be the focus coil. The exception is when one of the Alnico magnets popped loose inside the coils housing.
Alnico has been known to pop back from demagnetizing. And when if it looses any strength, my understanding has been that it would cause a change on the focus range, but not effect if the coils can continue to focus.
I think the issue with VDC using that SUPER coil may have something to do with demagnetizing the coils that may have been exposed to a large magnetic field, or possible somehow they're doing something with the coil to get the magnets back to to spec??
Now give this some thought; If somehow VDC could use that Super coil to charge the magnets and get them back to spec. Why couldn't they also over charge the magnets and make the focus better? I don't see that happening, and the reason has to do with the graph that Scott posted. the actual fine point of focusing has very little to do with magnet strength, but appears to have more to do with a precise point of magnetic strength. At least based on the graph, which shows a range above and below ZERO.
-----
Anyway, I posted to this thread on this because when comments like this are posted, I sometime get PM's or emails asking me about (in this case) the bad (or weak) focus coils in the Marquee and should they be replaced.
My answer is: No.. because I'm not aware of a need to replace a focus foil other than a popped magnet. And I'm sure both VDC and the previous owners made sure the coils were within spec before leaving the factory. Now somehow if the coils have somehow degraded over the years, it's still something thats new to me.
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