CurtPalme.com Home Theater Forum

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

Yesterday, I was retesting grayscale calibration on my 2004 VDC/Marquee 9500 and I found a weird issue: green tube never goes totally black, even if I set brigtness and contrast to 0 or I set G2 and drive setting to very low values and even if I power off the green tube by remote (pressing COLOR 1 or 3 etc...). Disconnecting the scaler, hooked by HDMI to Moome internal V2, and then testing the PJ alone, nothing changes. This issue only affects full black (it is always very dark grey, as the tube can light the screen), but I can nail down graysale fom 5 IRE to 100 IRE.
Collaterally, it's about 2 weeks that I noticed that powering off the PJ, the green tube doesn't go suddenly off, but it "draws" some faint elliptic green forms at the center of the screen, for about 2 seconds, and then goes off.

Any ideas?

Thanks for your answers

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Swap neck cards and see if it follows.

Nashou

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

OK, I've swapped green with red neck card, but nothing changes... Sad

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Hmm do you have a HVPS and Vim to test?

And does your Vim have the Peaking circuit? A variable cap would be on all three op amps. if so you might not have that adjusted correctly for the source frequency your using. That circuit is great if your only using one resolution, but if your using more than one then you have to adjust it for that as well and you now have to make a decision , leave it at your most watched res or just remove it.

Athanasios

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

Yes, I have both VIM and HVPS to swap; I will try this evening...
For the Vim: I don't know if it has the peaking circuit, will see. But what is strange is that the PJ has worked flawless for about 10 mounts, so I don't think there's any issue with the (eventual) peak circuit. Anyway, I will see...

Thanks so much..

Carmine

blange · Joined: 12 Aug 2010 Posts: 16 Location: Germany

does green immediately turn off if you unpower the projector? green tubes are known for have afterglow but i think in your case, the problem is somewhere else..

**Curt Palme** · Posted: Mon Aug 16, 2010 1:51 pm Post subject:

You should measure the G2 wire to see if the G2 adjustment actually changes the voltage. Typical 'normal' voltage is 550 to 700 volts or so, and it should run from say 500 to 800 volts as the G2 goes from 0 to 100 (voltages are not critical, only the fact that it changes as you ramp the G2 up and down.

Swap video leads on the VIM to rule out the VIM as being an issue.

It could be a bad tube. The problem could go away after some hours of running, and if not, a tube swap is in order. Sad

Oh, it also could be glycol leakage onto the back plane if the set is floor mounted.

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

Update:

1) swapped VIM cables
2) swapped the whole vim card
3) swapped the HVPS

At the end: nothin' changes: the green never goes full black and, when the PJ is switched off, the green tubes turns off about 2 seconds after the others, drawing nice pictures at the center of the screen (it looks like Aurora borealis Sad

).

So, do you think the tube is broken? Have to say it still is bright, perfect focused and G2 is 58... I don't know how many hours it run, as I bought the set second hand, and anyway I projected to buy a new one as it shows some uneven burn (looks like it was used in a simulator), but I am afraid I could have the same problem with a new tube, if the issue is not the tube itself...

Any help?

Thanks for everyone.

Carmine

**Curt Palme** · Posted: Mon Aug 16, 2010 8:10 pm Post subject:

Yes, that's what's called a contaminated tube. The problem might go away in some (10-few hundred) hours of running it, so unfortunately either put up with it, or get a new tube. Sad

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

You could try lightly tapping the neck of the tube if it is contamination while its running. It might fall off and burn off with a light show inside the neck of the tube. I used a 1 inch square piece of wood. Just light taps will do.

Athanasios

tse · Joined: 03 May 2006 Posts: 1014 Location: Sweatbucket, Fl.

It sounds like your tube has secondary emmisions. If you can find someone with a Sencore 7000 tube tester the tube can be fixed. There is some contamination on the cathode that the tester can remove.

Scott

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

CIR Engineering · Posted: Tue Aug 17, 2010 2:43 pm Post subject:

Look on ebay for a tube tester.

craigr

karmat63 · Joined: 19 Dec 2007 Posts: 157 Location: Italy

adimarten23 · Joined: 18 Aug 2010 Posts: 4

I have a marquee 9500 ultra which has worked well for well over a year. Its been reliable Unfortunately after about an hour through a film im sure it clicked and then went off. On restarting the projector only the green tube was displayed on the screen with white lines faint to see across the screen. Looking into the tubes the red and blue where showing faintly.