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Thread: CRT-monitor problem

  1. #1

    Default CRT-monitor problem

    My friend gave me an old crt monitor that was disassembled to atoms. Well i finally got everything put back together, but the monitor only shows this.


    I don't need any answers that tell me not to go digging inside a crt. I just wanna know what's the problem.
    Thanks

  2. #2
    Join Date
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    It could be any number of things since the monitor was completely taken apart.

    I would start with verifying the VGA cable is good, I've had plenty of old monitors where the VGA cable was pinned against a wall at a hard angle or moved around a lot, which eventually caused wires inside to break or short together and cause garbage on the screen. Use a multimeter in diode mode and probe each pin to each wire inside the monitor and make sure none are going to more than one. There are several ground lines so you'll want a VGA pinout for reference.

    The other thing it could be is bad solder connections on the logic board. Check for solder connections which look bad and reflow them with new solder.

  3. #3

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    It looks to me like the horizontal sync is getting triggered too early - probably at the point where the horizontal PLL starts to become sensitive to the hsync input pulse (if it was getting triggered too late then lines that should be vertical would be going right as they descend the screen rather than left). Probably not too difficult to fix, especially if you have a schematic and an oscilloscope.

  4. #4
    Join Date
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    Seconded. You want to check the horizontal frequency. On some setups, this is adjusted with a slug-tuned coil--if your friend dropped the ferrite slug out the coil, you'd get this kind of thing.

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