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Thread: PCjr Monitor Question

  1. #1

    Default PCjr Monitor Question

    I've been having some issues with my IBM PCjr monitor. I had to reposition the yoke to fix some color and convergence issues, and I think I've almost got it, but I'm not sure. The text is now legible and when at look at the simple test pattern the internal diagnostics provide the lines are a solid color again. However the text is a little fuzzy to my eyes. I don't know if this is because the PCjr monitor isn't the greatest (it's really an IBM CGA monitor) or if my convergences are still off. I want to say that it's the latter, but maybe someone here can help me determine that for sure. Here's a close up picture I took up the text for Zyll, as you can see the text isn't 100% white, but as I said I don't know if this is normal or not for a PCjr monitor.




    Here's the same picture zoomed out a bit:




    And zoomed out a bit more:


  2. #2
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    Looks like the convergence needs tweaking on your monitor. Has the image size changed at all (would point to a power supply issue). Has the monitor been handled roughly lately?

    Adjusting convergence with the proper test pattern is fairly straightforward, albeit tedious. Looks to be mostly confined to the red gun.

  3. #3

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    Quote Originally Posted by Chuck(G) View Post
    Has the monitor been handled roughly lately?

    Adjusting convergence with the proper test pattern is fairly straightforward, albeit tedious. Looks to be mostly confined to the red gun.
    No to the power supply issue, but yes I've messing with it trying to straighten out the picture. How would I go about adjusting the red gun? Is that with the second set of convergence magnets or does the yoke need more adjusting?

    Is there a good test pattern generator program I can use?

  4. #4

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    I found Trixter's CGA Compatibility program which helps a bit. One thing I noticed is that when the background for the main page is displayed it seems to 'bow' a bit in the center. Could that be the cause of my issues? You can't see it so much in these pictures, but it's noticeable in person. I tried moving the yoke a bit to see if I could fix the bowing, but it didn't seem to change. I'm not sure I want to keep messing with it and completely break things.






  5. #5
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    That's called "pincushion distortion" and can be corrected. There is usually a whole array of magnets on the yoke along with other controls. Your best bet is to find the service manual for the monitor and follow their alignment procedure.

  6. #6

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    Those last two screenshots make the clarity problem even more apparent, since some vertical lines are fuzzier than others (for instance the "C"s in "CGA" vs. "Compatibility").

    What machine/graphics board are you running this on? The font has single-dot strokes, unlike the CGA/PCjr's double-dot font. Someone correct me if I'm wrong, but IIRC the Jr. monitor had a larger dot pitch than the 5153, and perhaps that's at least part of the issue here... since a double-dot font would make it much less of an issue.
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    Blue on top, red on bottom points to convergence. Maybe this will help. Some patience and a beer or two will help; also a mirror.

  8. #8
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    Quote Originally Posted by VileR View Post
    What machine/graphics board are you running this on? The font has single-dot strokes, unlike the CGA/PCjr's double-dot font. Someone correct me if I'm wrong, but IIRC the Jr. monitor had a larger dot pitch than the 5153, and perhaps that's at least part of the issue here... since a double-dot font would make it much less of an issue.
    There was a thin-font modification for the PCjr, and if this is the PCjr I'm thinking of, I saw Tempest buy it at VCFMW about 6 years ago. It also has a 9.54MHz mod :-O

    The PCjr monitor has the second worst dot pitch of all my TTL color monitors; it's something like 0.43. Some numbers for comparison: http://www.vcfed.org/forum/showthrea...283#post104283
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  9. #9

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    Quote Originally Posted by Trixter View Post
    There was a thin-font modification for the PCjr, and if this is the PCjr I'm thinking of, I saw Tempest buy it at VCFMW about 6 years ago. It also has a 9.54MHz mod :-O

    The PCjr monitor has the second worst dot pitch of all my TTL color monitors; it's something like 0.43. Some numbers for comparison: http://www.vcfed.org/forum/showthrea...283#post104283
    Yes I have the Thin-Font chip in my PCjr. I can set it to the wider one and see if that helps.

    No it's not the one you're thinking of, I got my PCjr 15+ years ago and it doesn't have any speed mod.

  10. #10

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    Turning the ThinFont to 'Normal' actually makes things worse. The convergence blurriness is even more apparent.

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