AVS Forum banner

Status
Not open for further replies.
1 - 20 of 22 Posts

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #1 ·
I recently got a Barco BG800, from a forum member who moved up to an NEC. Similar to what other newbies have done, I thought I'd share some of my comments, questions, and experiences here in the forum. My goal is as much to have fun and a learning experience, as to (eventually) enjoy watching movies on it. Since I don't have boatloads of free time, this odyssey will probably take a while, and proceed in bursts and lulls.


I played with it a bit while in a floor-mount configuration, shooting to a 16x9 Plas-Tex screen (84.8 x 47.7) taped to a wall, though I haven't committed to using Plas-Tex for my final screen (due to the 1.0 gain). I'll probably be going with a Behr ultra-white (1.4 gain) or Goo (1.6+ gain) screen for the real deal, possibly a bit larger since I won't have the Plas-Tex size constraint.


I finally got my ceiling mount completed, and the PJ hung, doing an unassisted one-man lift (using a hook and ring attachment method, and removing the lenses and boards first to make it light enough for me to pick up, ~100 lbs).


Then I started checking things out on it, preparatory to fine-tuning the throw distance. One of the first discoveries I made, having removed the lenses to optimize raster use, is that unless CRT burn is significant, you can't see it with the lenses on! I had checked very thoroughly when I first got it, and none was visible thru the lenses. With them off, however, it's pretty easy to see. It also depends on what kind of light source you're using to examine them, with sunlight being the best (and fluorescent not quite as good).


Fortunately, with 4000 hours on the clock, it is fairly minimal. Blue is the worst, just at the point where there's a definite brown tinging to a rectangular region. I'd still categorize it as very mild, which is lucky, since it's obvious that the majority of hard use it has seen was improperly installed too far from the screen. I.e., the wear pattern doesn't come close to filling the phosphor, with 1/2" and 3/4" gaps on the sides, and 3/4" and 1" gaps on the bottom and top. Green and red are much better, wear wise, with only the slightest tinge on the green tube, and a real strain to see any hint of color shift on the red.


None of this came from the previous owner, who put 1400 hours on the clock running full raster-width 1.85 and 2.35 material. That was undetectable. All was put on it by owner n-2, or earlier.


I was interested to see that the '8"' Barco tubes (Sony 07MP) had a phosphor area of ~5" wide and 4.5" tall. Also that there is some black foam-type material around the front periphery. In the case of the green tube, it actually sticks out far enough to occlude ~1/4" of the phosphor, which hopefully won't be an issue, since I don't think that material can be stuffed back :) in without crumbling.


I did get stymied pretty early on, while looking for the rasters. I dropped the contrast and raised the brightness... and no raster. Dropped and raised them further... still no raster. Dropped contrast to 0 and brightness to 80+ and, you guessed it... no raster. I gave up on that temporarily, because the battery in the remote decided it was a good day to die, but eventually it dawned on me that it must be no rasters could be seen because the G2 levels were too low. I was hoping not to have to mess with those, because the PJ has already had gray-scale calibration with a colorimeter, and that was one task I would prefer not having to re-do. But if I bump the G2 high enough so I can see the rasters, I guess redoing the color temp will be mandatory?


So I didn't get to do any geometry adjustments yet, but know enough (from reading here in the forum) not to use the internal patterns, instead either an external source, or patterns genlocked to the external. The primary disadvantage to the genlocked patterns being that the default lines are not very fine? When I was playing with it on the floor, I was using AVIA on a DVD player, running through a DVDO iScan. Since there was a problem with my motherboard, and I'm waiting on a replacement, I won't be able to do an HTPC setup initially, and was wondering if I set everything up using the iScan at 31.5 kHz, will I have to re-do my raster and distance settings when I hook up the HTPC at ~55 kHz (720p @72 Hz)?


The other question I had was why are the internal patterns so useless to use? It seems to me that if I set up a custom cross-hatch in PR1-4 at 55 kHz and 72 Hz that the only thing that would differ from running those frequencies on my HTPC would be the front and back porch settings? Is that possibly also the reason why when you call up any of the internal patterns that they go way off the phosphor at the midpoint settings? (minimal porch timings) And since you're never supposed to run the beam off the phosphor, why does Barco configure the internal patterns so you always do, when you first call one up? Or does this indicate that the V/H deflection trim pots are set too wide to start?


Interestingly, even though the user-adjustable settings range from 00-99, internally they go from 0-127. Which explains why there are 2 clicks at '0', and many other settings. I.e., there are unlabeled half-steps at 27% of the settings.


There were a few more findings, and a couple questions, but that should be enough to start. Comments are always welcome.


- Tim
 

·
Registered
Joined
·
7,136 Posts
I finally got my ceiling mount completed, and the PJ hung, doing an unassisted one-man lift (using a hook and ring attachment method, and removing the lenses and boards first to make it light enough for me to pick up, ~100 lbs).


Taking out all the cards and removing the lenses helped me enormously as well for lfiting the unit up - though I had two other people do it while I directed it into my unistrut mount.

I was interested to see that the '8"' Barco tubes (Sony 07MP) had a phosphor area of ~5" wide and 4.5" tall. Also that there is some black foam-type material around the front periphery. In the case of the green tube, it actually sticks out far enough to occlude ~1/4" of the phosphor, which hopefully won't be an issue, since I don't think that material can be stuffed back :) in without crumbling.


I'd give that black foam a shove back in if it's in the lightpath - the foam in my BG800 is completely recessed... (this foam stuff's a great idea on Barco's part - it keeps dust build-up out of the viewable area).

But if I bump the G2 high enough so I can see the rasters, I guess redoing the color temp will be mandatory?


Yep - Your G2 should be properly set first to begin with, then do your colour temp.

So I didn't get to do any geometry adjustments yet, but know enough (from reading here in the forum) not to use the internal patterns, instead either an external source, or patterns genlocked to the external. The primary disadvantage to the genlocked patterns being that the default lines are not very fine?


Noticed that as well... the genlocked patterns are not as fine as, say, the Nokia monitor tester patterns I run on my HTPC.


Tim - your other questions are good ones (I've noticed the same things), but I'm afraid I don't have answers!


Kal
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #3 ·
Kal, thanks for the comments.

> I'd give that black foam a shove back in if it's in the lightpath - the foam in my BG800 is completely recessed... Noticed that as well... the genlocked patterns are not as fine as, say, the Nokia monitor tester patterns I run on my HTPC.
 

·
Registered
Joined
·
7,136 Posts
Quote:
Originally posted by VideoGrabber
Actually, even the internal crosshatch pattern in the Barco can be improved upon, but not from menu settings. Using PC control in the Barco, I noticed you can configure as fine a line width as you like, as well as the line density. It's all fully programmable. You can even configure the position of vertical and horizontal lines, to use as markers, for example.
Really?? I simply assumed that using a PC to control the thing via RS-232 simply let you navigate and use the existing menus.... I didn't know that you had increased functionality if you went the RS-232 control route.... interesting!


Is there anything else of interest that you can do via PC control that you can't do through the regular menus on the BG800?


Kal
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #5 ·
Kal wrote:

> Is there anything else of interest that you can do via PC control that you can't do through the regular menus on the BG800?
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #6 ·
I've got a question about horizontal linearity. More than one person has had at least minor problems with the H-linearity being different for the 3 guns at the left-hand side of the sweep, making horizontal convergence difficult in that region. It's been stated several times that the BG800 has no user-level H-linearity adjustments. However, I'm wondering about service-mode adjustments?


In the Service manual, the H-Deflection module description relates that the h-linearity coils that are on the side are frequency dependent, and nominally adjusted at 15 kHz. However, there are two other adjustments at other frequencies (P2 at 22 kHz, and P1 at 50 kHz) that cause secondary coils to be magnetically coupled to the main linearity coil.


What I'm wondering is if these pots could be used to tweak h-linearity, or if they just set the trigger points for the 3 zener diodes, controlling the bias voltage on Q1? If that's the case, can T1 be adjusted to trim the h-linearity at higher scan frequencies?


Barco documentation indicates that deviations in h-linearity on this PJ should be less than 3%, all the way out to 90 kHz sweeps, so there's got to be some reason why numerous people are experiencing these linearity difficulties in the 45-55 kHz h-freq range.


- Tim
 

·
Registered
Joined
·
7,136 Posts
Good question Tim! I'm one the (many?) that has horiz. linearity problems ... mostly on blue for me, but if I could tweak this out a bit on red too I wouldn't be pushing convergence as hard in the middle left of the screen. (I'm running at 54Khz: [email protected]).


Kal
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #8 ·
Thanks for the reply, Kal. It looks like we could have kept this in PM. :) Without your responses, I'd be talking to myself in an empty room. Actually, I tend to do that sometimes. :D [If you look at the various Barco threads I've posted in, you can see that I'm going for the longest list of unanswered Barco questions of all time.]


Before I bought my Barco, I noticed this problem in h-linearity just in the last few inches on the left-hand side. The red was skewed one way, and the blue the other (wrt the green).


When I first got it home and temporarily set it up in a floor mount, on the same sized screen, the problem was gone. But I don't know if that was due to the inversion, or that I was only running it at 31.5 kHz with an iScan. I guess I'll find out when I get back and complete my alignment and calibration process, and start running it at higher frequencies again.


Whether it's a problem for me personally, or not, I'd still like to understand all the technical ins & outs of the Barco. If I spent less time at work (where I'm posting this now), and more time at home, I'd probably be able to figure out some of these for myself. It's just that I know there are some folks here in the Forum with many years of Barco expertise, and I was hoping to be able to tap into some of that knowledge. Maybe I need a catchier title for my thread? ;)


- Tim
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #9 ·
I've been thinking about the vertical size issues, as Kal described them in a forum posting back in March...


> I couldn't reduce my vertical height enough electronically to squish the image down to 16x9 ratio without playing with the vertical hold pots quite a bit. Doing this also caused some odd geometry problems that I wasn't able to correct by staying in the 30-70 range for all convergence grids no matter how perfectly I did the mechnical setup.
 

·
Registered
Joined
·
7,136 Posts
Quote:
Originally posted by VideoGrabber
Even when using an external source (DVD with AVIA through an iScan), though the settings did not have to be reduced as much, the values were still very low. As I recall, just fitting 4:3 at 31 kHz dropped the vertical down to 38..... After all, if 4:3 is the maximum possible, why wouldn't it be possible to have that fit on the phosphor at a base electronic vertical setting of, say, 80 (instead of 50)?
Interesting Tim - I've never done a 4x3 setup so I just assumed that in 4x3 mode the vert. size was likely around 70-80 (or at least around 50 if they never expected anything other then 4x3 screens to be used).


We need a the Barco engineer here who designed the 800 here to pick his brains .... :) I don't understand some of their design choices, but then, I'm no expert!


Kal
 

·
Registered
Joined
·
1,191 Posts
Hi ---


I didn't want you guys to take this thread to PM, so here is a question ...


Tim said--->>>

Quote:
The only other things that occur to me at the moment are ForceBlockMode, which lets you have more than 2 configurations for one frequency set; and direct parameter access, which lets you tweak any of the 208 settings without having to navigate the menu tree. That could be a real time-saver, especially when tweaking settings that interact.
Tim, what is the purpose for this? This sounds useful to me... maybe.


Thanks.
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #12 ·
Pocatello,


the purpose of ForceBlock mode is to get around the limitation of only having two configuration memories (e.g. 5 and 95) for one frequency setup. Using ForceBlock lets you have as many as you'd like.


The purpose of DirectParameterAccess is to avoid having to traverse the menu tree in either RandomAccess or Guided modes, to move between settings. So no more Enter, Step, Step, Enter, Step, Enter, then Adjust, then Exit, Exit, Step, Enter, Step, Step, Enter, Adjust... and back and forth.


All of the adjustable parameters could be available on screen at the same time. Just click one to activate and make it the current parameter for up/down tweaking, or grab a slider and drag it directly, then grab another... The time-savings for making a series of adjustments could be substantial, not to mention less aggravating.


- Tim
 

·
Registered
Joined
·
1,191 Posts
thanks.... clear as mud!


When I set up my HTPC, this should all become clearer. Thanks!
 

·
Registered
Joined
·
3,901 Posts
Just a tiny note on seeing your raster. You stopped too soon. Turn contrast off, turn brightness ALL the way up. It won't hurt anything, and you will not needlessly muck up your G2 settings. Most pj's I've played with cannot light up the raster at less than 98% brightness with the contrast off. Its quite common. PS: this is a very informative thread, a real benefit to the forum.
 

·
Registered
Joined
·
274 Posts
Hi Guys,


I've been away from the forum for a while and am late stepping in to this thread, but the question about horizontal linearity is definitely an on going issue for many owners. A question I want to ask is about your horizontal linearity on the green tube (this is something I had overlooked on my BD801s). This is where to start, I think; otherwise, you are working hard to align to a bad reference.


There are two pots that can be adjusted on the Horizontal Deflection board. One contains an egg-shaped core, the other is a digital pot (as Tim has mentioned in an earlier post). They interact, so some back-and-forth is required to set things up right. This is a real bear to play with, as the only real way to do the adjustments on the core magnet is with an extender card. It is worth the effort though!


As far as keeping convergence closer to nominal settings, I have found that if the raster coils on blue and red are set slightly smaller than the green, it makes for less stress on the convergence circuitry.


Darrin
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #16 ·
gn2 wrote:

> Just a tiny note on seeing your raster. You stopped too soon. As far as keeping convergence closer to nominal settings, I have found that if the raster coils on blue and red are set slightly smaller than the green, it makes for less stress on the convergence circuitry.
 

·
Registered
Joined
·
274 Posts
Hey Tim,


I'm not sure I can give you a firm number on the number of turns required. I did my best to get an exact match on the raster widths using the image as a guide (since that is what you are really trying to converge, anyway), then backed the image width of the blue and red off enough to make a difference in the amount of convergence adjustment required. To say it another way, use the converge blue on green adjustment, and after the images are perfectly aligned in the center, use the raster coil on the blue to split the difference in the width on the left and right edges on the blue, as compared to the green. Repeat this with the red. The main point is the green becomes the reference. If your green happens to be the largest width (prior to adjustment), and you can't match the widths of blue and red (for the initial step), decrease the green raster until you can get a match with either the blue or red, then proceed to use the green as your reference.


Cheers!


Darrin
 

·
Registered
Joined
·
3,053 Posts
Discussion Starter · #18 ·
Darrin wrote:

> This is a real bear to play with, as the only real way to do the adjustments on the core magnet is with an extender card. It is worth the effort though!
 

·
Registered
Joined
·
274 Posts
Hi Tim,


Yes, I guess that could work, as long as the material used was non-ferrous, AND non-conductive. The core has a square shaped hole in the top that you can get a tool into.


Darrin
 

·
Registered
Joined
·
460 Posts
The tool you use also has to fit really well as those cores break very easily...


Dave
 
1 - 20 of 22 Posts
Status
Not open for further replies.
Top