CurtPalme.com Home Theater Forum

[perisoft]

So, I'm finally starting to set my bg808s up for 1080 - i72 as it happens, which is odd, but hey, you know me. Anyway, the green looks fantastic - vertical on/off lines are pretty much |||||. The astig on green (I've replaced all the tubes at one point or another) isn't perfect but I can still nail the focus pretty well.

The blue isn't half bad - vertical on/off lines are just barely discernable at 1920, though not fully-resolved like the green. But I haven't gotten the blue astig perfect either, so I expect that.

The red, on the other hand, is just AWFUL. I have the astig reasonable - focused one side it's a blob with a bright center; the other side it's a donut. The donut is round. I've set the focus yoke the best I can at 50 electronic, and the optimum focus stays around there. But I can barely see scanlines at **480p**!!! What the...?!

At higher resolution, the red can barely resolve 900p, 810p it resolves fully. But 1080p is just a gray (err... red) blob. What gives? Optical focus doesn't explain the horridness even at 480p. I can't think what to adjust next... I've gone through the whole sequence - resetting astig, electronic focus, focus yoke, etc etc... what am I missing? The green is **SHARP**... if I can get the red/blue looking like this I'm gonna be a happy freakin' boy - it already looks vastly better, INSANELY better, than it did before this round of tweaks - but I wouldn't be a CRTer if I didn't want the last bit. Help! Help!

[secstate]

I wonder if something is wrong with the electronics in your set. Every Barco I have had, and they have been many, the red has always been the sharpest. I have had a fair amount of trouble with the h-shift focus board in my time and that could, as it name implies impact electronic focus (though I have to say the failures I have had, have been on the h-shift part of the board). That board runs real warm too. The digital astig is controlled by one of the boards in the convergence tray. One other possibility do you still have Sony tubes in this set? They have that extra focus voltage coming of the G2 board maybe it is something there? I don't know on that as I have never had a Sony tubed Barco. This is one of those problems that can be hard to diagnose over the internet as there are lots of possibilities.

[perisoft]

Dunno, I'm still thinking it's gotta be user error on the setup somehow. That's the simplest explanation. But what things can you screw up in a tube swap that would cause lousy focus despite the focus coil moving through the whole range?

Does the electronic focus act to fine tune the coil, so you just need to get it close, or is it some kind of multiplier, and even if electronic focus goes from dots-to-donuts it's still not fully focused in the 'center' if the yoke isn't quite right?

[ecrabb]

I had a 1252 that I did a tube swap on that I just couldn't get the red to focus on no matter what I did. I just wrote it off as something wrong with the red tube, the magnetics, or the focus drive.

If you have the green looking great, you probably don't want to mess with it, but you could try swapping the focus the magnetics between the green and red tubes. If the focus problem moves to the green, you know it's not the tube itself.

SC

[perisoft]

Oh, man... yeah, I'm not about to swap magnetics. I barely have time to do tweaks as-is, and that'd be way too much downtime for watching Stargate SG1 with my wife.

I guess I'll try 'resetting' the astig and focus coil on red and redoing that. And I still don't have a clear relationship between the electronically adjusted focus and the focus coil - are they adjusting the same thing, or do they interact kind of like optical / electronic focus?

[Tom.W]

I wonder if it could be a lens issue... I would highly recommend color filtered HD 144 lenses for your projector. Do you have a spare lens you can try ? Could be one of the elements is out of alignment but not very likely.

[perisoft]

Thought about that, but the scanlines are crappy even at 480p, where they should be half an inch thick! So it's definitely not optics.

[Tom.W]

So if you look through the lenses at the Red CRT tube face is it blurry compared to Green ?

[secstate]

Tom makes a good point. Look at the tube face, to confirm it is an electronic versus optical focus issue.

[Elaine Benes]

With all the effort you've already expended, and being able to get good focus from the other two tubes, I'd bet on it being the tube. There are some tubes which simply don't focus very well, be it age or whatever. I've come across a couple of 180DMB's which were like this, but they are the only EM focus tubes that I've experienced this with.
One thing you can do that might improve the focus somewhat is to do your tuning of astig and focus at high contrast levels so that when you back the contrast down to the normal use level you have the focus and astig dialed in as good as possible.

[perisoft]