Noticed colors seemed washed out suddenly, then realized that red colors and tones are missing from my picture.

Haven't changed anything. Really. No, really!

The basic convergence pattern doesn't show red behind the yellow. I ran the mechanical setup to project only red - it casts a dim red pattern on the screen, around 20% the brilliance of blue or green. Pattern shows on raster, just no "oomph".

Any advice regarding how to do isolation and debug will be greatly appreciated.

Charlie

Funny that's the same problem I had with a BG1209 recently.
In my case it wasn't the neck board but that's where I would start in your case.

Swap the neckboard between red and green and see if the problem goes over to the green. If so it's a bad neck board.

That's a starting point for your trouble shooting at least.

Thanks, will do.

ok for the 1,925th time in the last 4 years, did you ever check the P14 filament voltage in that machine? :) Seems like a lot of people still haven't done this.

I think it's actually the 1,926th time :)

If you are running component cables to/from your projector, double check that the red is good and snug on both ends.

It happened to me once.

ok for the 1,925th time in the last 4 years, did you ever check the P14 filament voltage in that machine? :) Seems like a lot of people still haven't done this.


What he said.


1927.

Hello

Push COLOR, 1 for red only and # for a grid then look in lens, run Contrast up and see if faint image, if visible then the high filament ate the gun.

But would it happen so fast?
It seems like the other day it was alive and kicking and then all of a suddenly it went dim?

I thought that running the P14 too high would over time (a long time) wear the filaments out?

I bet this has been the response to at least 1000 of those questions - "the guy I bought it from told me he did it".

I'll check it myself tonight.

That was case here too, I bought marquee 7500 with dim blue.. Tested tube with tester/rejuvenator, good green and red showed numbers like 150 and bad blue was 20-30.. And filament voltage was little over 7volts( that was adjusted/checked about six months back to 6.3v) And guy who sold that to me sayed that blue went dim quite sudden.So there is not always that slow fading emission issue..
Ok i tried to rejuvenate that dim blue and WOHAA got emission up :p Sadly that last just 30sec :mad:

I thought that running the P14 too high would over time (a long time) wear the filaments out? well that would seem to be what should happen but unfortunately all the posts about this describe an all "of a sudden" type failure of the cathode.

I bet this has been the response to at least 1000 of those questions - "the guy I bought it from told me he did it".
I'll check it myself tonight. most people who post about it have never read the Marquee technical bulletins and the ones who do know about it were told by the seller " I checked it and it was fine" . If you don't know for sure that the circuit was modified then you should check it once a month IMO. If you haven't done the modification, then think of it as your favorite tube amp. Checking the bias is not a big deal and only takes 5 minutes. ;)
Luckily for you there is a complete set of Marquee tubes on flea-bay with a perfect Red for $100. The guy's in PA and he's honest.

Wow, didn't know that "sudden death" was a common thing with the P14 voltage.
That's scary.
Will keep alot better tabs on it from now on then.

I'm a newbie when it cmes to fixing CRTs (or any electronics at that) but I do have a meter. I looked at the posts and want to check P14. Looked at picture on etech site at http://www.etechvideo.com/a4p1.htm and have some basic questions.

Having never done this before . . . looks like I attach the red lead to pin 14 on the connector and set my meter to DC volts. Is this correct? To what do I attach the ground lead on my meter?

Then I fire it up and have a look at the voltage.

Did I miss anything?

Anything I need to watch for or do to ensure I don't fry the CRT or, less importantly, myself???

Also followed Tim's advice (Push COLOR, 1 for red only and # for a grid then look in lens, run Contrast up and see if faint image, if visible then the high filament ate the gun.)

What I see looking at the lense is a nice clear image on the lens with the contrast as low as 10 and an image that gets more brilliant as the contrast is raised.

Does this mean the high filament is fried? I ask because what I see is slightly different than Tim described as the symptoms of a fried filament (my images ain't faint.).

I think figured I out how to read voltage off the two pins at the p14 plug and read -9.54 to - 9.56 volts. Not good

The seller also told me that this 8500 has Barco P16 tubes. How do I check that?

What are my real next steps to a) fix the voltage issue, b) confirm beyond a reasonable doubt that the red tube is indeed fried, c) get this sucker back up and running?

Thanks!

Wow! 9.54 Volts are INSANELY high!

Turn that sucker down right now.

The only way you can see if there are P16 tubes in it is to remove the tubes and have a look inside the housing at the label located on the right side of the tube bell.

What needs to be done if the filament voltage is too high?

Geno, the LVSP needs to be modified, see

http://www.curtpalme.com/Marquee_Maintenance2.shtm

CHris.

WOW, almost 10 volts :eek: I can't believe any of your tubes are still putting out light. :confused: Who the hell put P16's into this machine left that stock P14 circuit in it? :mad: You need to rip that thing out and send it to Tim or Curt for modification.
Gino you have nothing to worry about, that circuit was completely re-designed on the Utlra's and they got rid of the trim-pot (adjuster) completely.

You can do the LVPS mod yourself but it does involve some soldering work. For now you can just turn the voltage down on a tiny trimpot located along the left side of the LVPS.
You should be able to adjust this trimpot even with the LVPS still installed through the sideplates.

draganm: Yeah but just to be sure it may be wise to see if the LVPS hasn't been changed out to an older issue even in Ginos case.

Guys!

Gino is good to go, I fan modded both of his Ultras........

I don't buy the 9.54 volts. Even with the pot wide open, I don't think the circcuit hits that high. Check it with another meter...

I don't buy the 9.54 volts. Even with the pot wide open, I don't think the circcuit hits that high. Check it with another meter...
Unfortunately the allowable adjustement on this circuit in stock form is 2v to 12V :( that's why it's so problematic and why Sly's mod in the Marquee Maintenace thread was so good. It not only replaced the crappy trim pot it actually narrowed the range of the adjutsment.

Guys!

Gino is good to go, I fan modded both of his Ultras........

Tim, wasn't worried about my Ultra's. I know you did the necessary mods etc... Part of your A1 service mate :)

I do still have an 8500 though.

I don't buy the 9.54 volts. Even with the pot wide open, I don't think the circcuit hits that high. Check it with another meter...


Buy it........we take Paypal!!!!!!!!!!

Never having soldered anything lighter than sheet metal, I surrendered to my own incapacities and so drove my broken unit the 40 mi down to Hi Rez in Ashland, MA. I took the CRT too :-)

9.5 VOLTS!! That makes my butt pucker! :eek:

Never having soldered anything lighter than sheet metal, I surrendered to my own incapacities and so drove my broken unit the 40 mi down to Hi Rez in Ashland, MA. I took the CRT too :-)
smart man, while your there have them check some of the other rails on the LVPS like the 85VDC to the HDM. They have some really cool performance mods too if you have some extra cash burning in your pocket.

9.5 VOLTS!! That makes my butt pucker! :eek: as well it should considering a brand new set of 8" tubes is $1800.

So does anyone have a source for the parts for the lvps mod? I don't want to replace the parts with others that might drift.

Some related questions:

- can one test the filament voltage (and maybe also other voltages) on a stand-alone LVPS? (my M9000 is now completely dismounted for cleaning)

- I read in a post (can't remember by whom, but he was one of the experts here) that the filament voltage drift may occur only in Marquee's built between late 1995 and ??? Can somebody confirm this?

- what kind of mods can be made to the LVPS besides those to filament voltage and fans?

Thanks

Some related questions:
- can one test the filament voltage (and maybe also other voltages) on a stand-alone LVPS? no, it's a circuit and needs to be tested as a circuit

(- I read in a post (can't remember by whom, but he was one of the experts here) that the filament voltage drift may occur only in Marquee's built between late 1995 and ??? Can somebody confirm this? Christie digital re-designed this circuit sometime in 98


- what kind of mods can be made to the LVPS besides those to filament voltage and fans?
Thanks nonw that i know of, although there has been some talk in the past of improved AC filtering on some of the rails. the biggest improvements come from modding the video chain for improved high badnwidth performance

http://www.curtpalme.com/forum/viewtopic.php?t=2377