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Thread: Focus Adjustment on Apple IIe Monochrome Monitor?

  1. #1

    Default Focus Adjustment on Apple IIe Monochrome Monitor?

    I have an Apple IIe that I've owned for about 12 years now, with a Monochrome Monitor IIe.
    Sometime earlier this year, I replaced the potentiometers that control the brightness, screen height, and vertical hold. The dials were beginning to come loose.

    The monitor works just fine and can display, but something seems off.

    The display isn't as sharp as I think it should be, because I'm noticing a slight trailing/ghosting/blurring effect on the right side of every screen element. It's enough to be noticeable and affect the graphical quality.

    Is there a focus or alignment control somewhere in the monitor's electronics to adjust the sharpness or phase or whatever can get rid of the trailing?

  2. #2

    Default

    There is internal focus and sub-brightness controls. Video smear can be a number of things from bad grounding of a cable to a bad coupling capacitor. Post a good closeup photo of what your seeing with an 80 column text document of some sort.
    Defocused or brightness flaring look different than video smear from a cap or ground

    Larry G

  3. #3

    Default

    As I was taking the pictures, I did notice that the scanlines are not uniform in brightness, even though everything on the screen is white-colored when output to a color television or composite color monitor. I had to decrease the brightness of the monitor to get good detail with my smartphone's camera.
    Attached Images Attached Images

  4. #4
    Join Date
    Sep 2016
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    Melbourne, Australia
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    306

    Default

    Look like a brightness issue rather than focus, turn your sub bright control down a little.

  5. #5

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    It looks like it might possibly be a 'blooming' issue.
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  6. #6

    Default

    Sure does. A picture of the whole screen would help confirm that.

  7. #7

    Default

    A video while slowly increasing the brightness would be proof positive.
    If you're looking for DS/DD or DS/HD 3" or 5" floppy disks, PM me. I've got some new, used, and factory over-labeled disks for sale.

    There is a crack in everything. That's how the light gets in. -- Leonard Cohen
    ☞ Time flies like an arrow; fruit flies like a banana.

  8. #8

    Default

    Also as Larry noted it looks like there's a bad cable or video chain problem.

  9. #9

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    Ok, after looking elsewhere, I seem to have found the problem.

    The video-out jack on the montherboard seems to be loose, as the quality varies when jiggling the connector. I'll check to see if there's a dry joint there.

    EDIT: Ok, I figured it out. The barrel of the video jack was connected to its grounding frame only by friction and had oxidized (as retrogear says below). I soldered the barrel in place, and now it shows a nice picture.
    Last edited by T-Squared; November 8th, 2017 at 11:08 AM.

  10. #10

    Default

    FYI - Notice how the horizontal lines are brighter than the vertical lines? That indicates loss of high frequency video from a weak coupling cap or oxidized video connector (also dry joint) as you say.
    Sub-brightness misadjusted causes bright flaring trailing to the right of where it should be. Defocus causes dimmer flaring either above AND below or left AND right of where it should be (stigmatism).

    Larry G

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