Return to the CurtPalme.com main site CurtPalme.com Home Theater Forum
A forum with a sense of fun and community for Home Theater enthusiasts!
Products for Sale ] [ FAQ: Hooking it all up ] [ CRT Primer/FAQ ] [ Best/Worst CRT Projectors List ] [ Setup Tips & Manuals ] [ Advanced Procedures ] [ Newsletters ]

 
Forum FAQForum FAQ   SearchSearch   MemberlistMemberlist  Photo AlbumsPhoto Albums  RegisterRegister 
 MembershipClub Membership   ProfileProfile   Private MessagesPrivate Messages   Log inLog in 
Blu-ray disc release list and must-have titles. Buy the latest and best Blu-ray titles to show off in your home theater!


Marquee 9500LC color shift / color uniformity issue
Goto page 1, 2  Next
 
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors
View previous topic :: View next topic  
Author Message
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Tue Mar 19, 2019 8:49 pm    Post subject: Marquee 9500LC color shift / color uniformity issue Reply with quote


        Register to remove this ad. It's free!
I'm experiencing color uniformity issues/color shift with my Marquee 9500LC. You might also call them warm/cool "hot spots."

The projector is ceiling mounted, approx 98" away from my 82.5" (diagonal) screen. Screen material is Carl's FlexiWhite 1.1 gain.

There are circular zones of greater blue and red intensity. A warmer/red area on the right side (nearer to the red tube) and cooler/blue area on the left side (nearer to the blue tube).

This makes it difficult to enjoy black and white films. Pure white is noticeably different from left to right -- cooler to warmer. Noticeable even with color films depending on the scene.

Zone adjustments don't make any difference here as this isn't the edge but somewhere between edge and center.

I don't know if this has to do with the projector being closer to the screen than is typical, greater than usual toe in, the screen material itself, or some other parameter. Perhaps it's something I'll have to live with. Looking forward to your thoughts.
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Wed Mar 20, 2019 12:34 am    Post subject: Reply with quote

Hello

There are three possibilities. First, your zone contrast settings may be off; most folks remove the contrast modulation board if installed, it is behind the plate below (on the ceiling) the control board.

Second, some unevenness in white field is expected if blue is sharply focussed, try defocussing blue a little.

Third, you could have uneven wear in the phosphor or some crap clouding the glycol; look into the lenses while running white field test pattern.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Wed Mar 20, 2019 1:56 am    Post subject: Reply with quote

Thanks for the reply, Tim. When I got the projector, the contrast modulation board was indeed removed -- I reinstalled it, actually. The left & right edges showed yellow bias due to the blue tube edges being dimmer than the center. So I boosted the left & right blue zones to get better uniformity. I have reset the zone adjustments, though, to test with everything back to 50, and the color shift persists...

Just looked through the lenses, no glycol related obstruction or strangeness. Could be uneven phosphor wear, but it's nothing readily apparent. Green and red look pretty uniform, though the blue tube edges seem to show more (less?) wear than the center (different 'shades' of blue, lighter at the edges).

Defocusing the blue tube more doesn't make much difference -- actually the warm (red) "hot spot" is more noticeable than the "cool" one.
Back to top
Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 23813
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Wed Mar 20, 2019 2:58 pm    Post subject: Reply with quote

I'd pull the lenses off. Seeing glycol discoloration is usually masked by putting the lens on. It's much easier to see with the lenses off. Had a Barco 909 in here a month ago with two tubes contaminated with yellow glycol. Saw it immediately with the lenses off.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Wed Mar 20, 2019 11:34 pm    Post subject: Reply with quote

Looking in the lenses with a light (I've never removed the lenses before and I'm reluctant to do so just now), I do notice corner yellowing in the blue tube. Glycol yellowing? Hard to see anything in the red or green, though, because of tinted C elements (or is it tinted glycol?). But the zone correction I'm doing is almost all about the blue tube - boosting sides and corners to around 90. I have read this is hard on the tube, wears it faster, and I would like to solve the issue -- as well as the color shift. The projector is on the ceiling, though, and changing the glycol seems like a challenging procedure if not impossible in a ceiling mounted unit. The issue would have to get worse I think to justify taking it off the ceiling and doing that work. But I welcome any notes and suggestions.

On another note, could sunlight be yellowing the glycol? I don't have lens caps and the projector is subject to diffused sunlight during the day. Should I make a point of covering the lenses?
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Thu Mar 21, 2019 3:21 pm    Post subject: Reply with quote

Hello

Not likely a sunlight issue. Steel glycol fillhole screws have put a little rust in the fluid. The blue tube will have to come down to enable fluid replacement, and stainless steel fill hole screws are preferred.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Sat Mar 23, 2019 3:30 am    Post subject: Reply with quote

I suppose the first step is taking off the lens and getting a closer look at what's going on with the blue tube. With most of the apparent yellowing in the corners, does that mean there is crystallization of the glycol, or fungus, on the surface of the glass?

The Marquee Teardown procedure doesn't show lens removal, but from the images with the lenses off, it looks like you remove just the four corner bolts (square pattern), leaving the other four intact. (This is also what's shown with the Sony model in Graham's CRT instructional video.) And will lens removal affect lens flapping at all?
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Sat Mar 23, 2019 5:12 pm    Post subject: Reply with quote

No

It is corrosion that brings yellowing. It will be obvious if other stuff is in the fluid or stuck to the tube face.
Back to top
garyfritz



Joined: 08 Apr 2006
Posts: 10763
Location: Fort Collins, CO


PostLink    Posted: Sun Mar 24, 2019 1:19 am    Post subject: Reply with quote

The corners are also the thickest part of the glycol area, no? So if there's any yellowing, it would be most noticeable in the corners/edges.

Back to top
barclay66



Joined: 27 Jun 2011
Posts: 1253
Location: Germany

TV/Projector: Marquee 9500 Ultra


PostLink    Posted: Sun Mar 24, 2019 4:36 am    Post subject: Reply with quote

garyfritz wrote:
The corners are also the thickest part of the glycol area, no? So if there's any yellowing, it would be most noticeable in the corners/edges.

Absoutely!
And this is why You never should try color filtering via tinted glycol on a LC tube...

Kind Regards,
barclay66
Back to top
View user's photo album (25 photos)
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Fri Oct 18, 2019 12:22 am    Post subject: Reply with quote

Hi all. I'm going to replace the yellowed glycol in my 9500LC blue tube LC chamber in the next few days. The chemicals and the syringes have arrived.

It wouldn't be possible for me to even consider taking this on without Tim's excellent ETech Marquee LC tube removal guide.

My PJ is ceiling mounted. I'm going one tube at a time, starting with blue. If all goes smoothly, I'll replace glycol in the green and red LC chambers as well.

Certainly feeling a bit of trepidation -- mostly about the possibility of frying the board(s) (or electrocuting myself).

I've read that to discharge the tube, you take the anode wire at the splitter/bayonet connector end, and touch the metal tip to the metal chassis of the PJ. I want to confirm that this is the right procedure. Should I discharge all three tubes by removing each anode wire at the splitter, or is that unnecessary if I'm just removing the blue tube?

Thanks in advance, and I welcome any other tips or suggestions as I prepare.
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Fri Oct 18, 2019 3:28 pm    Post subject: Reply with quote

Thank you


for your kind words. On the ceiling you would want to remove the horizontal and focus boards first so they don't crash to the floor. They are in the metal sleeves in between the tubes. The yoke plugs are all color-specific so mark them to go back together correctly. "Front-middle-rear" would suffice. The tubes would only have a slight or no static charge after sitting off overnight. If there is some crap in the glycol, drain the old glycol and fill half full and slosh with 100% ammonia for ten minutes and drain that and rinse again with distilled water. The tube and c element should be nicely clean after that. If there are chunks of stuff then you have a bigger problem. The rubber bellows can start to dissolve after years and that means bellows replacement. I can do that here if needed, for a charge. Note where every tube bolt came from, you don't dare mix them up.

I also recommend first, testing the tube strength by noting the value of G2 bias needed to just light up the second block in the stairstep test pattern. If bellows are failing on a worn out tube, it makes more sense to replace the tube. With the room darkened and BRITE/CONTRAST both at 50, G2 over 76-77 means the tube has less than 2000 hours of use remaining.

E.mail me if you need more help with this, I can talk you through it on the phone.

ehometech8022@yahoo.com

Do get some stainless steel fill hole screws. 6-32 Allen screws 3/8" or 1/2" will do, you'll need six. A tube with lens on is near 40 pounds so you would need to take the lenses off or get two helpers.


Tim at E-Tech


Last edited by Tim in Phoenix on Sat Oct 19, 2019 3:12 am; edited 1 time in total
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Fri Oct 18, 2019 8:00 pm    Post subject: Reply with quote

Ammonia rinse followed by distilled water rinse is a great tip. Ditto the stainless fill hole screws. I'll get a hold of those supplies.

My tube hours are a bit under 2500, so they should have plenty of life left. I was not aware of the G2 method, however -- good to know.

Really appreciate your offer to talk through it on the phone, Tim. Will definitely get in touch with further questions if I have them. I'm feeling more confident about the process already. Thanks for all the good info.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Wed Oct 23, 2019 8:41 pm    Post subject: Reply with quote

I successfully replaced the fluid in the blue tube's LC chamber. Pretty challenging and time consuming as a first timer. The removal of the yellowed glycol, rinsing with ammonia and distilled water, and adding new glycol was also messier than expected. But all seems to have worked out. I reassembled and was able to drop my blue zone settings to normal and see improved color accuracy right away, especially in the corners. Again, thanks to Tim for the guide on the Etech site, which was absolutely essential.

One issue remains, however: I have quite a few air bubbles in the LC chamber fluid. I used a mix of 80% propylene glycol / 20% glycerine. Exactly what fluid or mixture to use has been a subject of debate, and I read every thread I could on the subject. Tim, I know you recommend triethylene glycol (perhaps with some amount of distilled water) - I found the cost prohibitive, unfortunately. Others use pure propylene, or IceClear AF (mostly glycerine), or some form of glycol mixed with glycerine. Nowhere, however, did I read anything about air bubbles in the fluid. I can't see any evidence of them onscreen, but I imagine the bubbles must have some negative impact on sharpness. Hoping that within a few more days (or weeks) they'll dissipate. Curious if anyone's heard of this before.
Back to top
Curt Palme
CRT Tech


Joined: 08 Mar 2006
Posts: 23813
Location: Langley, BC

TV/Projector: All of them!


PostLink    Posted: Thu Oct 24, 2019 2:40 am    Post subject: Reply with quote

They will work their way out, no worries. Happens with most tubes that I've refilled.
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Thu Oct 24, 2019 2:18 pm    Post subject: Reply with quote

We almost always get tiny bubbles, they will dissipate in few days.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Fri Oct 25, 2019 2:53 am    Post subject: Reply with quote

That's encouraging to hear. Thanks Curt and Tim. I'll post an update in the next week or so re bubbles. Hopefully by then the fluid will be clear.
Back to top
rotoscoped



Joined: 08 May 2017
Posts: 18
Location: Virginia


PostLink    Posted: Wed Feb 05, 2020 12:44 am    Post subject: Reply with quote

Hi all. Posting a long-delayed follow up to the "bubbles in glycol" issue. There are still a few bubbles remaining at the top and bottom of the LC chamber. Those at the top are out of the path of the beam/phosphor, while those at the bottom, lining the curve of the LC glass, are to some degree in the path -- these are very tiny bubbles.

The bubbles were very plentiful at first, and didn't begin to disappear for close to a month, at which point I stopped checking (a watched pot never boils, or something like that). The majority of the bubbles seem to have dissipated between 30 and 60 days after refilling the chamber.

Otherwise, the 80% propylene glycol / 20% glycerine mix remains perfectly clear (no yellowing), over three months in. I'll check in another month or so to see if the remaining bubbles ever completely disappear.
Back to top
Tim in Phoenix



Joined: 21 Oct 2006
Posts: 4254
Location: Phoenix


PostLink    Posted: Wed Feb 05, 2020 4:13 am    Post subject: Reply with quote

Hello

If you can't see bubbles on screen then you need not worry.
Back to top
AnalogRocks
Forum Moderator


Joined: 08 Mar 2006
Posts: 25555
Location: Toronto, Ontario, Canada

TV/Projector: Sony 1252Q, AMPRO 4000G


PostLink    Posted: Wed Feb 05, 2020 5:32 am    Post subject: Reply with quote

Tim in Phoenix wrote:
Hello

If you can't see bubbles on screen then you need not worry.


Wasn't bubbles a chimpanzee? Laughing

_________________
Tech support for nothing

CRT.

HD done right!
Back to top
View user's photo album (27 photos)
Display posts from previous:   
Post new topic   Reply to topic   Printer-friendly view    CurtPalme.com Forum Index -> CRT Projectors All times are GMT
Goto page 1, 2  Next
Page 1 of 2
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum