AVS Forum banner

Status
Not open for further replies.
1 - 10 of 10 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter · #1 ·
My Barco 500 has a very dark picture all of a sudden. I did a little research and troubleshooting and I have some information I would like to present hoping that someone can help with a solution. Looking right into each of the 3 barrels with a dark DVD playing [The Matrix]


Red is bright as ever and crisp!

Blue is bright but a bit blurry. This tube is going out (not the problem)

Green, only the very bright parts of the image show, the rest is just green. This seems to be the problem.


This is what I think:


Something is up with the Green. Is it likely the tube or could these symptoms point in another direction?


What do you all think?


Thanks for the help!


Armando
 

·
Registered
Joined
·
968 Posts
Armando,


This sounds a little different than your other post on this. If you really only think the green is going dim while your brightness and contrast are at the same level, the first thing I'd do is swap the output amplifiers between green and red and see if the problem moves to the red tube.


Is there still a time period for this to happen? Have the G2 adjustments on the focus module been tweaked at all during this time?


Mark
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #3 ·
Great thanks for the advice. The reason for the difference in posts is because it turns out that after the projector has been on for a couple of hours this is when the green gets really bad, so i looked in the barrels after it had been on for awhile and the results were different than my previous hasty post.


When I get home, I will try swapping the output amplifiers and see if it is the problem.


What are the G2 adjustments, focus module?


Thanks again.
 

·
Registered
Joined
·
3,729 Posts
Basically the G2 control is the output of the tubes. 1 G2 for every tube.


You tweek G2's to get good grayscale etc.


- Rick
 

·
Registered
Joined
·
968 Posts
Armando,


On the focus module there are two rows of red, green, and blue knobs. The top row (if your projector is on a table) are the electronic focus adjustments and the bottom row are what are commonly called your G2 adjustments that Rick was describing.


It sounds like you're getting a picture change over time and without regard to these controls so I'd still swap the output amplifiers. If you haven't done that before, there is a small 4-5 wire connector on the back card side you pull off and a larger 8-9 wire connector on the front tube side you pull off, and then you just loosen the two screws above the amplifiers on the rail and they slide off.


I would recommend resisting any temptation to adjust the two potentiometers on the amplifiers unless you have an oscilloscope and service instructions.


Mark
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #7 ·
Mark, I just got home from work and switched out the Green and Red output amplifiers and I see no change in image. Since now we know the amplifiers arrant the problem, i suppose I can leave them they way they now are. (correct me if I'm assuming wrong).


Typing as i work... WHOOOOHOOOOO!


With your help Mark, I think i just got it fixed. I started playing with the G2 control for the Green, turn it up a few notches and I'm back in business! Time will tell and ill see if it go dark again this evening after a few hours of onnage.


It still strikes me as strange that the first time it began getting dark I am absolutely positive that i did not alter the G2 controls. It may be moot now but I am curious what might have caused my dilemma in the first place.


I will let you know if its darkens up this evening.


Thank you Mark and Rick for the assistance!
 

·
Registered
Joined
·
2,124 Posts
armando

There is another possibilty.

I had a similar problem with a Marquee 8500. The green would lose intensity and the image would appear red. In this case it was tarnished connections on the coax that runs from the Video Input module to the tube Neck Board.

Thanks Tim for the tip on that problem. I cleaned the connections and all is well.

I am not sure if the Barco has the same kind of connections but it is worth a look. I am sure that by turning up the G2 it would mask the problem if there was indeed a problem with connections in the video signal chain.

Just a thought.

Steve
 

·
Registered
Joined
·
15 Posts
Discussion Starter · #9 ·
Steve, nothing hurts a good cleaning. Thats a great idea, i will clear up those contacts to make sure i don't overwork the G2


Good looking out, Steve thanks!
 

·
Registered
Joined
·
968 Posts
Armando,


I'd keep a close eye on the projector since you thought it has a time-induced abnormality. You are okay leaving the two output amps swapped since you've played with the G2 controls since swapping them.


What type of input video sources are you using? Any video processor like a doubler? What I usually do when I'm setting up a 500/800 initially is to input a color bar pattern on the composite input and put color, tint, brightnes, and contrast all to 50 and tweak the picture with the G2 controls. If you happen to have anything else in the video feed path that can adjust the picture I set them to their mid-position settings as appropriate as well.


Mark
 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top