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Yellowish picture on Marquee 8500.

1643 Views 22 Replies 6 Participants Last post by greyleopard, Jan 21, 2009

greyleopard

Discussion Starter · Dec 29, 2008

My projector color doesn't seem correct. The whites appear light yellowish. I've tried changing between RGBHV and HDMI and but the effect is the same. The color space conversion does not seem to be incorrect. Any ideas of what this could be? Is one of the CRTs going bad. If so, how can I tell?

Charlie

1 - 20 of 23 Posts

nashou66

· #2 · Dec 29, 2008

*First how long have you had this PJ.

*have you changed anything recently.

*how often do you watch it and when was the last time you used it before the color went bad.

*Did the color go bad all at once or over time?

Athanasios

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Tim in Phoenix

· #3 · Dec 29, 2008

Hello

Read this carefully http://www.etechvideo.com/techtip1.htm and try to get a measurement of the filament voltage at P14.

.

greyleopard

Discussion Starter · #4 · Dec 29, 2008

I've had the projector for about 4 yrs. I usually watch it 6 days a week. I started using my VIMHD a few weeks ago and the problem started a few days ago. If I change an input or if the pictures completely changes, it looks better and then progressively get worse.

draganm

· #5 · Dec 30, 2008

a yellow shift means a drop in the output of the blue tube. It could be tube realted , like Tim suggested checking the P14 voltage and also going thru the entire grayscale set-up.

A quick check you could do is next time it's "normal"

1)Push the # key a few times and bring up the Grayscale pattern,

2) then push "color and 3" to bring up just the blue.

Can you see a difference between the darkest and second darkest square (you should be able to).

Then, when the problem happens again repeat the above 3 steps. If you can't see a difference this time then you can pin-point the blue tube output as low.

If it is the blue, it could be anything from the tube dying (does this machine have the P14 modification?), or a problem the Blue G2 circuit from High volatge power supply, OR possibly a problem with the Video Input module.

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Gary Murrell

· #6 · Dec 30, 2008

hopefully you don't have severely yellowed glycol, although I doubt that causing your issues as it would most likely be all 3 tubes

these Ehome guys will get you straightened out

-Gary

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greyleopard

Discussion Starter · #7 · Dec 30, 2008

Ok, I've got some homework. Volt meter here I come. I'll check the P14 to see what I get. Thanks for the support and I'll let you know.

greyleopard

Discussion Starter · #8 · Dec 31, 2008

I ran the P14 voltage test. When I turned the projector back on it started around 19V and progressively ticked down to 8V. I turned it off, watched it tick down and restarted the projector. The voltage rose to 7.8 - 7.9. Clearly I have a problem. Could using the VIMHD card have had an effect? Either way, I'm going to have to resolve this. I guess my next step is to repair the lvps. I have extra projectors but I'd rather solve the problem. I'll start searching for threads, links, or tech bulletins on how to repair this. Does anyone have a quick link?

nashou66

· #9 · Dec 31, 2008

Quote:
Originally Posted by greyleopard /forum/post/15419117

I ran the P14 voltage test. When I turned the projector back on it started around 19V and progressively ticked down to 8V. I turned it off, watched it tick down and restarted the projector. The voltage rose to 7.8 - 7.9. Clearly I have a problem. Could using the VIMHD card have had an effect? Either way, I'm going to have to resolve this. I guess my next step is to repair the lvps. I have extra projectors but I'd rather solve the problem. I'll start searching for threads, links, or tech bulletins on how to repair this. Does anyone have a quick link?

Thats the first procedure in my thread on Curts site.

Marquee Modifications and Performance Enhancement

Athanasios

greyleopard

Discussion Starter · #10 · Dec 31, 2008

A quick google search found it after my last post. Thanks for the response. Has anyone heard if the Moome VIMHD card is triggering the LVPS failure? It is posible that it was a coincidence. I've decided to pull a power supply out of one of my other units until I repair the first one. I am concerned that the VIM card may trigger the same thing in the next supply. Are Moome's later card more robust? The VIMHD works wonderfully?

draganm

· #11 · Dec 31, 2008

Quote:
Originally Posted by greyleopard /forum/post/15422932

A quick google search found it after my last post. Thanks for the response. Has anyone heard if the Moome VIMHD card is triggering the LVPS failure? It is posible that it was a coincidence. I've decided to pull a power supply out of one of my other units until I repair the first one. I am concerned that the VIM card may trigger the same thing in the next supply. Are Moome's later card more robust? The VIMHD works wonderfully?

The P14 voltage and Moome are 100% NOT related. Look inside your LVPS at the trim pot (adjustemnt ). I bet it's a dirty Gray color and printed MEXICO on top and it sounds like yours is failing completely and acting like an intermittent short. At between 8 and 20V I sure hope all 3 of your tubes aren't damaged, the blue for sure is probly on it's last leg. the factory spec. for the tube filament is 6.35VDC +/- 1%.

greyleopard

Discussion Starter · #12 · Dec 31, 2008

I hope the tubes are ruined as well. I've run the unit for about 5 hrs since I noticed the problem. Hopefully I noticed in time?

greyleopard

Discussion Starter · #13 · Jan 1, 2009

Well, I just installed the replacement LVPS. I started running the grey scale setup. Got to blue and could barely see it. I guess the blue tube is toast. I really didn't want to recalibrate another projector. Not to mention hanging the damn thing. This sucks!

nashou66

· #14 · Jan 1, 2009

Quote:
Originally Posted by greyleopard /forum/post/15427684

Well, I just installed the replacement LVPS. I started running the grey scale setup. Got to blue and could barely see it. I guess the blue tube is toast. I really didn't want to recalibrate another projector. Not to mention hanging the damn thing. This sucks!

Just swap the tube, it can be done on the ceiling you just have to be careful and have a little ingenuity.

Athanasios

nashou66

· #15 · Jan 1, 2009

Oh and what are your G2 and drive values for the red and green, if those are bad then swap PJ's. And swap out the newer boards so you have the latest boards in the working PJ.

Oh And Happy new year

Athanasios

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draganm

· #16 · Jan 1, 2009

Quote:
Originally Posted by greyleopard /forum/post/15427684

Well, I just installed the replacement LVPS. I started running the grey scale setup. Got to blue and could barely see it. I guess the blue tube is toast. I really didn't want to recalibrate another projector. Not to mention hanging the damn thing. This sucks!

it's too bad you didn't find this forum before you started this project. The P14issue is well know with early Marquee's and it's the first thing we tell people to check. Any Tech. who works on these will usually make the fialment voltage mod. job 1.

greyleopard

Discussion Starter · #17 · Jan 2, 2009

I've tried to find articles on removing the CRTs but the only one is for the LC version. On air coupled CRTs, do I need to remove the top plate with the three large socket heads or loosen the clamp bars. Which one will give the least trouble?

nashou66

· #18 · Jan 2, 2009

Quote:
Originally Posted by greyleopard /forum/post/15441336

I've tried to find articles on removing the CRTs but the only one is for the LC version. On air coupled CRTs, do I need to remove the top plate with the three large socket heads or loosen the clamp bars. Which one will give the least trouble?

Remove the top plate. And the two vertical bars as well, makes it easier.

Athanasios

greyleopard

Discussion Starter · #19 · Jan 18, 2009

I've pulled the LVPS boards out of my projector as well as an extra projector. I bought the components but without a desoldering station, and due to my shaky hands and failing vision, it's difficult for me to make the mods. Can someone quote me a good price to do the work locally or by mail? I could pull the board out of my 3rd projector if the price is good. I'm weighting buying the station vs. having someone due the repair for me. While I'm at it, I could get anamorphic mods on a couple of boards as well.

draganm

· #20 · Jan 19, 2009

since you have it all apart there's a few other boards you should service as well. The 2 large power filter caps on all 3 neck-boards and about 50 pieces on the convergence board just to name a couple.

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