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Focus problems with PC -> BD 600

Discussion in 'Projectors, Screens & Video Processors' started by ralphot, Mar 14, 2005.

  1. ralphot

    ralphot
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    Hi!

    Have succeeded to combine the sync signals from PC graphics card and got a picture on my Barco Data 600 fully readable. The sync is doing a good job.

    But...

    The focus and convergence does not seem to be any good.

    I have very nice picture from the BD600 from my DVD player connected through the Composite video input. But from PC - really bad.

    What am I doing wrong?

    Any idea someone?

    Ralph
     
  2. ledoctt

    ledoctt
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    Hi if you can put vidéo composite on your TT BD600 , Your TT have been modificated and the PCB board it's a RGB 15MHz+decoder . The Pc board will probably come to a Vision 600....

    The original PC board on TT Bd 600 it's RGB 30 MHZ and it's not working on Vidéo composite!!!

    What is your résolution ?? 800X600 56Hz ..
     
  3. ralphot

    ralphot
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    Hi ledoctt!

    Thanks for your response.

    What is TT?

    Yes, maybe my BD600 has been modified. Among the possibilities to connect composite video I have found a large circuit board placed under the lenses with a lot of TTL chips. What is that doing there?

    (see picture http://www.bohuswines.se/images/BD600.jpg)

    If it is modificated what was the purpose for that if one takes the original RGB away?

    I think that when there is the RGB and SYNC inputs with BNC connectors then the original 30 Mhz bandwidth RGB should still be there ?

    I have purchased a chip LM1881 to acheive composite sync from the composite video. Then I will connect my digital TV receiver and my dvd player through scart switcher with RGB.
     
  4. DowNtimE

    DowNtimE
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    The module at the front is most likely the autolock module.
    The lm1881 chip also gives out the vertical sync. Easiest way is to use the composite sync from the scart to the lm1881 and then use the comp. and vert. sync out from the lm1881 and connect them to barco's Sync connector using a bnc T-adapter. R, G and B comes straight from the scart.

    I think ledoctt means the TTL connector on the back of your barco the D-connector. He's correct that it's probably only 15 Mhz and only accepts CGA level video signal. So you will get a better picture if you use the bnc connectors to connect the incoming rgb signal.

    Also regarding your first post about bad focus and convergence when connecting to pc is most likely because your machine has been converged using standard 15khz video signal, if you connect it to pc using say 640 x 480 resolution, you have to do the whole convergence and focus again.
    The bd600 is an analog machine so it doesn't have any memory slots for different signals, you have to decide what is best for you and do the convergence and focus using that signal. Do not use the internal test patterns when doing convergence. Get a test dvd which includes test patterns and use that. The convergence is much easier to do and it will be just right.
     
  5. ralphot

    ralphot
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    Thanks :thumbsup:

    Well, I have not used the TTL RGB connector whatsoever. I built a sync combiner exactly like this: http://www.hut.fi/Misc/Electronics/circuits/vga2rgbs.html
    and fed the R, G and B signals directly to the BNC at the back from my computer. I was using 640 X 480 but the picture was really out of focus. (and/or convergence)

    I am in the beginning of designing my home movie theater and just want to clear out things before I screw things to the floor. I will floor mount my BD600 as my room height is a bit short, 2.2 meters.

    About the LM1881 chip, it's simple, I put in composite video, there is no composite sync in the scart! If there were I would not need the LM1881 chip. Out from the chip I get, among others, composite sync, hor sync and vert sync. I will use composite sync directly in to my sync BNC as they are negative syncs that BD600 wants.

    Yes, I was using the internal test pattern for convergence and it works good for the composite video input, so from DVD-player and digital TV-converter it looks fine. I then used the Nokia ntest in my computer: http://www.construnet.hu/nokia/Monitors/TEST/monitor_test.html
    and it were absolutley out of convergence so that is for sure the problem.

    I will report when I tried with RGB from my DVD and TV.

    I have also ordered a test DVD with all the test patterns needed.

    As I see it I must do different convergence adjustments for the composite video use and for the RGB direct use. I will for sure use the RGB inputs from now on!
     
  6. DowNtimE

    DowNtimE
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    Yes there is. Composite video from the scart = composite sync. Normal tv needs a sync signal just as anything else. Composite sync on scart is pin 19 (+) and 20 (-) if I remember correctly.

    I didn't like the lm1881 chip very much, mainly because it triggered macrovision on my dvd player. Instead I used el1883. It's a smd chip but gives out true horiz. and vert. sync. Very nice quality chip.
    Use only RGB and do the convergence and focus adjustments. You should be allright after that.

    Also I read on the other thread that you had some problems with your smps module and that you had to change a capacitor. I really suggest that you measure the +17v line on your smps. It should be somewhere near +17,4 volts. It causes all kinds of problems if that voltage is too low or too high.
     
  7. ralphot

    ralphot
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    OK, I can accept that but the sync signal has video between the pulses which I suspect could disturb the syncronization, but if not, then it would be OK to use the composite video as sync.

    I have tested that and looked at into the tubes with no RGB signal and a nice raster is present but with some disturbance in the lines, not clear so to speak.

    Do you think that I need an EL1883 or can I just connect the composite video as sync?

    So if you think that is all right I will just try to connect the lines right trough from the scart to the Barco. Should be interesting.

    Will report later how it went.

    Thanks, :smashin:
    Ralph
     
  8. DowNtimE

    DowNtimE
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    But you said you used composite video as sync???? The composite video from the scart is EXACTLY the same as normal composite video, it includes the sync signal. Normal RGBS connection uses composite sync AKA composite video to sync to the incoming signal. No matter if there's video or not. If you're taking the composite sync from the lm1881 it's exactly the same as composite signal taken into the lm1881, it doesn't enhance, strip or do anything to it.

    If your barco syncs to the lm1881 c.sync it should sync to scart c.sync also.
     
  9. ralphot

    ralphot
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    I am full aware of what the composite video consits of. It consist of sync pulses with video information between the line (hor) sync pulses. But not only that, also Luminance Output is pin 19 containing for s-video use. The LM1881 or the EL1883 takes the composite video as incoming data and ignores the video component. It gives clean composite sync and separate hor and vert sync pulses.

    I just wonder if the video information could disturb my Barco in the sync process. If not I need no LM1881 or EL1883.
     
  10. DowNtimE

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    I don't doubt that.
    You probably need the chip, my barco didn't sync to composite video signal. Also LM1881 doesn't give horizontal sync only vertical and composite, the EL1883 does give both hor and vert.

    I really suggest that you use RGB connection to barco, as it's definetly the best way in terms of picture quality on interlaced video. If you want to use PC then try 720x576@60hz, it gives a very nice progressive pal picture.
     
  11. ralphot

    ralphot
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    OK, you ar right, LM1881 does not give hor sync, looked at data sheet but it gives comp sync and that is what needed. However, I just finished the connection with scart to rgb and comp video as sync and it works fine! I did not see any degradation on the picture coming from sync instability but think that a pure comp sync is better. When I get the dvd with test pics I will do a convergence adjustment test. The final one is made when all are installed of course.

    Thanks for all your help, often is a discussion very helpful :)

    Ralph
     
  12. DowNtimE

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    Glad it works ok. I think the bd600 syncs better to different sources thanks to that autolock module. My bd650 doesn't have that so it's a little more picky about the incoming signal.

    Hope my posts have been helpful to you.
     
  13. ralphot

    ralphot
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    Yes, now I know what the autolock module stands for :)

    And yes, you have been most helpful, to discuss with someone helps the thinking process a great deal!

    Regards,

    Ralph
     

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