BD 801s raster centering magnets?

Discussion in 'Projectors, Screens & Video Processors' started by Andre Sveen, Jun 16, 2002.

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  1. Andre Sveen

    Andre Sveen
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    Do I have raster centering magnets?

    I have replaced my old burnt green tube with a new.

    The green picture is much lower than red and blue. I can not get there by adjusting the pots on the vertical def. board or using anything in the menus.

    I have done astig this evening. The blobs are all round and nice.

    So my next thoughts goes to the raster centering magnet, if I have any.

    Could anyone give me a complete checklist?
     
  2. Roland @ B4

    Roland @ B4
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    Andre the short answer is no.
    The magnetsfor an 801 on the back of the CRT neck are for controlling the shape of the spot rather than shifting it.
    The ones nearest the end stage control the width and height of the spot. (two pole). the other two nearer to the lenses contol the stigmatism ie the shape (four pole).

    You have two stages of raster shift one in the install menu the other in the geometry settings. The Installation one is global the geometry one per source.

    You need to go through the installation menu and centre the rasters.

    but as it is the green you have replaced it's probably worth resetting everything in the service menue to their mid possition. then delete all the blocks rather than trying to make the new tube fit the old tubes settings. Get the Red and Blue pots on the H & V boards midpositioned too or you will get conflicts. ( do this by counting the number of turns.

    Make sure the issue is not casued by the tube not being quite home in its clips relative to the lens. ( is the top/bottom focus different to before?)
     
  3. Andre Sveen

    Andre Sveen
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    Before you replied I tried to slightly move the CPC magnets assembly 0.5 cm forwards.

    I don't know, if this did the trick. Now I can center the green properly and I have seen my first movie after the retubing.

    I think this is weird, but I don't care. It works great.

    The reason why I tried is this.

    quote:
    --------------------------------------------------------------------------------
    [...]If the centering isn't corrected by that then an experienced technician will need to align the flare magnet rings near the rear of each tube neck, those will affect centering somewhat; if flare alignment doesn't do it then the technician will need to loosen and align the focus yokes, which affect centering considerably. If the horizons remain tilted then the glue holding the scan yokes will have to be chipped away to permit those alignments. All of these yoke alignments involve reaching amid lethal voltages inside the tube covers and are wisely left to experienced technicians.[...]
    --------------------------------------------------------------------------------

    Taken from a tread at www.avsforum.com I don't know who wrote this the only name I saw was Tim, so I might think it would be Tim at E-tech.

    I also had a tread in avsforum, but noone answered for days. Seems like they are having holidays.

    Thanks anyway Roland. I hope some others will have use for this information.

    Right now I am so excited I could jump through the ceiling.
     
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