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Thread: 8032 CRT issue

  1. #21
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    Quote Originally Posted by iz8dwf View Post
    Have you checked the rectifier diodes in the monitor's PCB? The big smoothing capacitor? The 18V linear regulator?
    These are absolutely the first steps in any kind of repair job.

    Frank
    I will check it too. Currently I have a very little free time, so I can spend some time fixing vintage computers just at weekend... maybe.

  2. #22
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    No problem.

    I have the same issue.

    A working job that pays for the hobby ...

    Dave

  3. #23
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    Quote Originally Posted by daver2 View Post
    No problem.

    I have the same issue.

    A working job that pays for the hobby ...

    Dave
    LOL

    I read in another thread about your pettester V.4, that works in the edit rom. Intrigued, I burned a 2716 eprom and tried it.

    surprisingly, the image was shifted on the left of the monitor, almost outside from the visible margin. However, it was a quite stable image, without flickering or shaking.
    Instead, with the edit (901474-04) eprom, the image is centered on the screen but it shakes a little...

    do you remember those big CRT who had the demagnetizing funcion? You pressed the button and the image started to shake a little before to get stable again... a similar flickering.

    So there is a difference between your pettester and the original edit rom code.

  4. #24
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    Quote Originally Posted by giobbi View Post

    surprisingly, the image was shifted on the left of the monitor, almost outside from the visible margin. However, it was a quite stable image, without flickering or shaking.
    Instead, with the edit (901474-04) eprom, the image is centered on the screen but it shakes a little...
    Hi giobbi,
    I thought Brazil has 60 Hz power? The 901474-04 is for 80 columns, 50 Hz systems. It might cause a little flicker, etc. Try the 901474-03 if you have 60 Hz power.

    I don't know what timing constants daver2 is using, but it does not matter as long as it is legible as it is only for temporary use in testing.
    -dave_m
    Last edited by dave_m; July 1st, 2019 at 11:29 AM.

  5. #25
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    Quote Originally Posted by dave_m View Post
    Hi giobbi,
    I thought Brazil has 60 Hz power? The 901474-04 is for 80 columns, 50 Hz systems. It might cause a little flicker, etc. Try the 901474-03 if you have 60 Hz power.

    I don't know what timing constants daver2 is using, but it does not matter as long as it is legible as it is only for temporary use in testing.
    -dave_m
    Thank you Dave, I didn't think at that! I will do a try, of course, and I will tell you the result!

  6. #26
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    Dec 2012
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    ...eventually I've discovered the floating image on the screen only appears when the 8032 is closed and the CRT assy get closer to the transformer... so I believe it's some kind of noise from the transformer. I will try to ground better the CRT section... unless you have a better idea or theory for that...

  7. #27

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    Grounding is electrical. What you're seeing is magnetic. You need some kind of magnetic shielding between the transformer and the CRT. Something is missing.

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