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Thread: IBM 5153 (CGA monitor) line voltage range

  1. #51

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    Managed to find a 5.1k resistor so changed R307 for that, pleased with the result, locks great at 50hz and still a bit of turn left on the vert hold pot so seems a good mod to me! Now I can use my pattern generator on it and it locks!

  2. #52
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    732

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    Quote Originally Posted by andrew96 View Post
    Managed to find a 5.1k resistor so changed R307 for that, pleased with the result, locks great at 50hz and still a bit of turn left on the vert hold pot so seems a good mod to me! Now I can use my pattern generator on it and it locks!
    You could add a resistor in series with the pot so you don't have to crank it as much.

  3. #53

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    Quote Originally Posted by GiGaBiTe View Post
    You could add a resistor in series with the pot so you don't have to crank it as much.

    no that would not have worked as the voltage on pin 8 of the HA11235 needed to be slightly lower when the pot was at minimum resistance, so the only way to do this was to lower the value of R307 to achieve this, this will not affect the locking at 60hz but at lease the monitor will now work on both vertical frequency's

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