CurtPalme.com Home Theater Forum

gholt · Joined: 10 Jan 2007 Posts: 47

I have recently replaced all 3 tubes on my BarcoData 808, and everything is working. Great! But I've noticed that each of the tubes glows at the bottom whether or not an image is displayed. The brightness and contrast don't seem to affect it.

I'm still some what of a novice, and so I've purchased Graham Johnson's video, and perhaps that will help me diagnose issues like this in the future. But can anyone help me figure this out? I use this projector in a planetarium, so even beyond the possible burn-in issue, it casts a faint glow onto the screen/dome.

I've attached a photo of the green tube, in case that helps. All 3 tubes have the same glow, at the same brightness.

Thanks in advance for any help you can provide.

Ile · Posted: Wed Sep 02, 2009 5:37 pm Post subject:

Chance resolution from your source to see if it helps.

It could be that your current resolution have so short vertical porch settings that ABL system don't have enough time for ABL pulse during vertical retrace and part off it is showed in tubes.

Other option would be turning ABL off and adjust G2 levels by eye.

gholt · Joined: 10 Jan 2007 Posts: 47

Thank you.
I changed the resolution, and the glow pattern changed, but didn't go away. I also tried changing to another source. I switched to port 2, where I have a DVD player connected, and the glow was still there, but it had a darker area in the middle of the glow, instead of a relatively uniform glow along the bottom.

This may be a stupid question, but what is ABL, and how do I turn it off? I do know about the G2 pots. I've adjusted them on my Barco 800s. I can't find ABL in the manuals.

As a side note, does anyone know the max resolution on port 3? For some reason, I was thinking it was 800x600.

**Curt Palme** · Posted: Wed Sep 02, 2009 7:25 pm Post subject:

Pull the lenses off, put electrical tape right on the tube faces. Put lens back on. Done.

akajester · Joined: 09 Jul 2008 Posts: 934 Location: Wisconsin

Your pj is same specs as my bg808. I've run higher than 720p without problems over port 3 but settled on 720p as it seems to be the sweet spot. I can faintly see the scan lines up close.

**AnalogRocks** · Posted: Thu Sep 03, 2009 4:18 am Post subject:

Aurora Barcoalis Very Happy

Mark_A_W · Posted: Thu Sep 03, 2009 5:59 am Post subject:

God, if that was a NEC I'd say the deflection had failed and it was about to destroy the tube..

But I have seen that on my Barco. Lile Ile said, I think it's the AKB/ABL line, but don't understand the details on this system on a Barco...so somebody explain it will ya???

damien55 · Joined: 20 Oct 2008 Posts: 101 Location: UK

Hi,

I have the same problem on my BG808. Someone suggested retrace lines but I'm not sure about that. It might well be this ABL pulse Ile is talking about.
I opened a discussion about the same problem in jan 2009 : https://www.curtpalme.com/forum_archived/viewtopic.php@t=14398.html . In my case the line actually ended up being on the tube face

You will notice that this line appears because we are in a widescreen format and that it should never be visible in a 4/3 configuration. If you want to move it a bit further outside the tube I think that adding some porch lines will move the picture down then if you move the raster up to compensate I think that this "ABL" line (or whatever it is) will move towards the outside of the tube face.
The other option is to move the screen up a bit to then have to move the raster up but that's not a very nice solution.

Damien

Ile · Posted: Thu Sep 03, 2009 11:09 am Post subject:

Curts method is effective and doesn't cause harm to tubes.

gholt · Joined: 10 Jan 2007 Posts: 47

Crap! I just made things much worse!
Thanks to all of you that have provided information and advice.

Yesterday, I tried Curt's trick of applying the electrical tape to each CRT face, and that produced only marginal improvements. So today, I was STUPIDLY trying to adjust the G2 levels with a metal screwdriver, and dropped it! Grrr! So, after a couple of spectacular sparks I was able to unplug the projector and retrieve the screwdriver. So now, not only is the separate convergence power supply LED out, something else must be out as well, because I'm not getting any picture at all on any of the tubes. When I power up the pj, I can see the usual glow in the socket of each tube, but no glow at all in the CRT face.

So, where do I go from here? If necessary, I have an 801s that I can swap parts for, but that will also be my backup pj while I'm going back to the drawing board on this 808, so I don't want to do any swapping for anything other than diagnostic purposes. I also have an extra 800 that I can use for parts if that will work.

Thanks in advance for your help. Sorry for making this worse and wasting the time you had already invested in helping me with the refinements.

RobertMfromLI · Joined: 29 Jun 2009 Posts: 114 Location: West Islip, NY

Never metal screwdriver for those tasks. Absolute worst case (cannot get a proper plastic one) scenario, cut down a plastic putty/spackle knife to become a screwdriver and use that. I know it's too late to save the damage already done, but hopefully it will help in preventing a recurrence.

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

gholt · Joined: 10 Jan 2007 Posts: 47

Robert, thanks for the tip, but I don't have an excuse, I had a plastic screwdriver. I just wasn't thinking.

Tom, thanks. I'm purchasing a couple of boards from Curt to try. Hopefully that will get me back on track.

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

PaulB · Posted: Wed Sep 09, 2009 7:14 pm Post subject:

Ha, I've seen the old Northern Lights a few times but believe it or not, what you see on the tube is exactly the way I saw them one night up in Shetland (group of Islands way north of UK mainland) - it was spectacular to say the least.

Maybe its God's way of saying that the Earth's G2 settings are out of whack Shocked

gholt · Joined: 10 Jan 2007 Posts: 47

Yes, I did think the "Aurora Barcoalis" was pretty clever.

And I have also seen the last part of an auroral display look very similar. Believe it or not, it's all about electric charges and magnets!

Thanks again to all who are offering their wit and advice. I'll let you know what I figure out when the boards arrive.

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

roland@b4 · Joined: 07 Jul 2009 Posts: 82 Location: Reading UK

It did stop the tubes glowing which was the original problem Wink