CurtPalme.com Home Theater Forum

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

So my new home theater is getting more and more ready. I have mounted the marquee in the ceiling a few months back, and watched a lot of movies since (while working with the reamins). Very Happy

But, I have this annoying thing with the red tube, something is definately broken in the projector;

Problem:
Red tube are never completetly shut off (unless powered off), it has a faint uneven noise floor, even when the projector is in "video mute". It can be seen when looking into the tubefaces, not on screen, which is why I never bothered with it before, but now I am about to do a real greyscale setup (any month now Smile

), so I thought I'd fix this before.

Could it be something on the video neck board?

Not sure if it has anything to do with this, but the red has always been the most troublesome tube (did a tube change about 2 years ago (all three)) to tune; mechanical astig/flare was nothing but a war between me and the red, and in the end I am not sure I succeeded. Blue and Green was very easy to dial in, in comparison.

So any suggestions on how to start the quest?

Tom.W · Joined: 09 Mar 2006 Posts: 6635

Do you also see diagonal lines on the Red tube when it should be off ? Could also be a G1 short in the CRT. Can you swap the video amps ?

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

Not really any diagonal lines, with some imagination, I can see a "pattern" going almost horizontally (but it is very faint an unsharp). Theres no distinct edges of the raster - it just blurs out.

Hmm complicated to describe. I tried to take a picture, but it does not really look as in real life; in real life, it is much more uneven, noisy, and kind flaming/pulsing. And more faint. But as you can see, the raster area is visible, albeit no sharp edges. Not sure if that means anything.

By "Swap the video amps", do you mean the neck boards? Or earlier in the chain?

Gino · Posted: Mon Apr 28, 2008 8:04 am Post subject:

Have you tried lowering red G2?

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

Yes, (just did again to be sure Very Happy

). There's no change at all. I.e. if I pull both G2 (and drive for that matter) down to 0, I still have this noise.

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

Edit: If that is not neckcard problem->then
One thing.. Red is never pushed so hard that green or blue, that can do little issues to tube elements, there can be contamination on cathode.. So trye run red on high contrast for while( select just red and pull up whitefield on marquees internal patterns) Shame that marquees does not have similar "run in cycles" feature that Barcos has. One barco user here in Finland had similar issues and that "run in cycles" proses worked ok.
But be sure that you got projector warm enought before you start that full contrast drive and maybe little defocusing is good to do before that so you dondt burn scanlines to tubes.

nuttall_chris

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

Hmm, so the verdict is contaminated tube.. Sad

Sending it back to VDC is quite complicated and expensive from here, and would have to be the last solution.

One thing that puzzles me is that I have the raster. Would it not be the whole tube if it was contamination? (I admit; I am a tube dummie, even if I swapped the three)

nuttall_chris
Did you see any other issues with your gun? (Such as complicated flare/astig)

1031
What kind of time do you suggest at max ? This sounds like a torture test on the tube... (!)

Apart from the irritating factor, is there any downsides by not fixing this issue?

nuttall_chris · Posted: Mon Apr 28, 2008 5:51 pm Post subject:

**Curt Palme** · Posted: Mon Apr 28, 2008 6:01 pm Post subject:

I don't know if it will work, but you could try flashing the tube, alternating 0 and 100 IRE rapidly. THat might dislodge the contamination. Maybe? If you can't see it on the screen, I'd leave it alone.

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

Thanks everyone!

I will try the all-white trick, but if that doesn't change anything, I'll live with it. After all, the tube is in good shape apart from this contamination. Just knowing what is causing this is maybe the most important thing..

1031 · Joined: 22 Mar 2006 Posts: 657 Location: Finland

If you can found dvd that has black/white pattern, trye play those two patterns in loop mode. Then you got "poor man´s run in cycles feature" Mr. Green

Ile · Posted: Tue Apr 29, 2008 10:37 am Post subject:

If you can use pc as source, you can use attached zipped folder as "field generator". After unzipping folder to hard drive, open it with Windows XP Picture and Fax Viewer. When you hit that screen putton (start slide show) B/W pictures inside folder start alternate in loop...

Gino · Posted: Wed Apr 30, 2008 3:00 am Post subject:

You're a clever man Ile! Wink

vespaman · Joined: 15 Jan 2008 Posts: 31 Location: Stockholm

So, just to close this one off, if someone else has the same issue;

I have found while dealing with other HV issues in my projector, that this is somehow connected with the HVPS, as it whent away after cleaning the contact fingers and changing HVPS. My guess is that the G2 for the red has an bad solder or perhaps a bad cap, or something the like. Will have a quick look at this later on today.

Very Happy