Questions about Barcodata 708 adjustments

Discussion in 'Projectors, Screens & Video Processors' started by the jayman, Oct 30, 2002.

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  1. the jayman

    the jayman
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    I have noticed that there are strong competence about 708 in this forum:)

    I bought Barcodata 708 projector a week ago and tried to get it adjustet as exact as possible. I have encountered couple strange things and haven't find any explanations for those.

    When I have done optical alignment for tubes, installation program succest that rasters should be centered. This is not possible because they are bigger than phosphor area in every tube. How can I adjust these smaller? Changing picture size won't affect on this because picture adjustments are not affecting in installation section of setup program. I also undestand that this is not a problem if picture size will be adjusted correctly later when tweaking picture (smaller than phosphor area). I just want to know if there are anything to do for rasters size.

    Another thing is that when making optical alignment, red and blue squares around the cross are bigger than green tubes square. This causes problems later when adjusting convergence. Blue has biggest square and biggest problems with convergence, so I have thought that these have to be related to each other.

    I have only owners manual for this Barco, not installation manual. So if these are in mentioned in the installation manual, I would like to buy it.
     
  2. Roland @ B4

    Roland @ B4
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    Hi welcome to the Forum.
    The 708 is a great little PJ I have had about 20 of these and still think it offers one of the best pictures from a CRT. But they do do some strange things like the over scanning raster that I have yet to get to the bottom of. Sometimes this will work. Go to a source you are not using or has the input disconected and delete all the blocks. Then set every thing to midpossition using the option in the service manual.
    Go to the random access menu and chose an internal pattern, select 15kz video (pal or NTSC it doesn't matter) adjust the size of the green so that it doesn't quite fill the width of the tube you can do a bit with the geometry as well whilst you are there. this memory block should then become the one the projector uses for its refference. and allow you to do the rest of the alignments.

    Your second issue sounds like some one has replaced some tubes at some point and not reset the width coils properly. Was this a private sale or from a company?
     
  3. the jayman

    the jayman
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    I'll try that tweak in next weekend, when I'm going to hang it in to ceiling.

    But that second issue:

    Projector is bought from private person, who bought it from company about a month ago with a one month warranty. It has 1260 hours on a counter and there aren't any wear on tubes. Chassis is like a new and seems untouched from inside. So I don't think that it has been retubed. Manufacturing year is 1997.

    One more point to the second problem: Those square width's are same in all three tubes, but the height is the problem. Also those squares aren't in the same horizontal height and it feels like blue should be pulled little upper. I have undestand that when making tube alignment, tubes can only be moved in horizontally, is this correct?

    Couple other questions:
    - Do you have installation manual for this model (is it possible to buy a copy)?
    - Can you also tell me how am I going to reverse the picture, when installing it in to ceiling?
    - In which installation phase electronic focus adjustment should be done and which kind of source?
    - And what's the function of three black regulators which are located in the middle of the projector when case is open and looked straight from above? There aren't any explanations in circuit board next to them.

    Thanks!
     
  4. Roland @ B4

    Roland @ B4
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    Jayman
    Send me an Email I have something to send you.
    [email protected]

    Vertical shift for R&G&B is in the raster shift section of the geometry menu.
    There are two pots which control the vertical height of the Red and Green.These should only need ajusting when a tube or coil is replaced.
    Yes the tubes only toe in horizonatally.

    I think the Black regulators you refer to are the linearity coils which should be white but with a black core. again I can see no need to adjust. You must use a plastic screwdriver or you could cook the projector

    Hopefully you are only looking at these things for identification and not tweeking. The only internal electonic adjustments that you shuld need to touch are the horizontal raster shift which are blue pots with brass tops one for red the other for blue.
     
  5. the jayman

    the jayman
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    You got mail!

    Still one question:

    You said:

    "There are two pots which control the vertical height of the Red and Green.These should only need ajusting when a tube or coil is replaced."

    If I want to adjust these, from where I can do this and how?

    I was just curious about those other regulators. I have found an explanation for any other switch unlike for those :)
     
  6. Roland @ B4

    Roland @ B4
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    Be carefull if you don't know what you are doing. There are some very high voltages on this and other boards that could kill

    Middle board two big black capacitors.
    Go down the board and find the two big black chips, next to those are two blue pots Vert red amp and Vert blue amp.
    I have only ever had to adjust these when the tubes have been replaced. I suspect some one has been playing.

    Before you adjust these, get your geometry sorted which means you will be adjusting just the green.
    Now Go to the service menu and set the CONVERGENCE to off or midposition which ever your software says.
    In the convergence menu adjust just the centre raster shift up or down of the relevant colour so that the centre line is converged. IF your red and blue heights are wrong very gentley adjust using a plastic screwdriver the two pots above.
     
  7. the jayman

    the jayman
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    I'm going to post pictures from circuits later on today. It helps us to understand each other better. I don't wanna get killed by misunderstanding :)

    I could also post pictures from installation phase, so you can see my problem better...
     
  8. the jayman

    the jayman
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    There are couple pictures from inside of the projector. Those black regulators can be seen from barco1.jpg picture. In picture barco2.jpg there are G2 and electronic focus pots. Third picture is overall view. Can you explain are other adjusments under the main board seen in picture three? How can I remove it?
     

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  9. the jayman

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    Second picture
     

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  10. the jayman

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    Third picture
     

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  11. the jayman

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    I have now managed to get main board open and take some pictures from inside. In first picture there are hor/ver scan connectors where the picture can be reversed. There are also in lower left those two blue pots which are for red/blue amplitude, am I right?

    Is it safe to adjust the whole picture when the main board is open? Can you tell me what parts in those pictures are most dangerous?

    Second picture will follow with more questions...
     

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  12. the jayman

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    Second picture from convergence connectors. Is it necessary to turn also these connectors when making ceiling mount?
     

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  13. Roland @ B4

    Roland @ B4
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    Jayman I've been away from the forum a bit
    Hopefully by now you have worked out you need to flip all 9 connectors to reverse the scans and convergence settings.

    That is a very new projector or it has had some work done recently judging buy the photos.

    I can't see from the pictures but can you confirm that there is a very thin single brown wire coming from the corner of the heat sink of the tubes. The 708 had particular problems overheating the tubes and could cause them to shatter they issued a FOC kit to shut the PJ down if they got too hot.
     
  14. the jayman

    the jayman
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    Roland,

    I have to thank you already. You have been so big help for me :blush:

    I've just done those amplitude adjustments and switched the picture around for ceiling mounting. Squares are now perfect :)

    I've also tried your method for adjusting raster sizes and it helps also in my case. Raster sizes are now also perfect. There are only one flaw in this method. When you delete all memory blocks, rasters are once again too big :( But now I know how to adjust them back.

    Answer for your question about brown wire is that i can't find it :( Does that mean that i have potential tube crack in front of me? Can you tell me more specific where to look it? Is the looked heat sink connected in to upper board and the wire is connected in to it?

    I also received new Skyworth 1050D DVD player with VGA output in last week and I'm stunned about picture quality with progressive PAL. DCDi rocks :D

    I'm using RGBHV cabel with T -connector to RGBS input. It works, but are there any risks for projector with this kind of sync combination? I've noticed that when i switch DVD player off, projector fills screen with green color for RGBS input. When turning player again on, everything is fine...

    And still some adjustment questions: Is there any way to move picture inside the raster vertically? I don't have need for it but I'm just curious. What about picture size inside the raster (both horizontal and vertical)? Only adjustment what i have found for moving picture inside the rasters without moving the raster is H-phase (moves picture in horizontal directions)...
     
  15. Roland @ B4

    Roland @ B4
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    Attached to the top of the tube near the very corner should be a silver temperature sensor it will be about 5x3x2mm bolted in place with a thin brown wire coming down to a small sub board attached to the input board.

    Vertical Raster shift for RG&B is in the Raster shift menu. under geometry settings.
    But the actual raster is determined by the video picture so the true answer is no.

    Green out put is down to your DVD player try unplugging it. Ibet the green goes away.
     
  16. the jayman

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    Thanks again,

    I'll check that sensor later on today.

    Couple other questions:

    Is it possible to change size of the projected image inside the raster, without changing the raster size?

    Is 708 really with EM focus? I've read so, put when I've looked beam focus and astigment adjustments those are like in electro static projectors if i understood those correctly.

    Are those pots (red green and blue) shown in upper picture with G2 adjustments same which are used for adjusting beam focus? Is electronic focus adjustments same as beam focus in Barco's?

    Where can I adjust the beam form (astigment) if i need to?
     
  17. the jayman

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    Still one more question:

    Is it possible to adjust horizontal linearity with this model? It seems that it isn't perfect at the moment.
     
  18. Roland @ B4

    Roland @ B4
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    there is a horizontal linearity coil at the top/back of the lift up chasiss. It will give limited adjustment
    The only way to get the horizontal spot on is to fit convergence on green. about 800 pounds
     
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