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Thread: Weird problem with my C64

  1. #1

    Default Weird problem with my C64

    Hi,

    Iím experiencing this problem with my C64.
    Sometimes it wonít start (totally blurred screen), sometimes it works peacefully, and sometimes I get this kind of behaviour:

    https://youtu.be/YYupUPGtfxY

    It could be the Vic chip... anyone has hints on this issue ?

    Thanks !

  2. #2

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    It could be an ic. Or oxidation, video cable, etc.

    You're using it w/an lcd, which adds many more possibilities.

  3. #3

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    I have an LCD TV that does that. Works most of the time though. I suggest you try it with another monitor to rule it out as the problem.

  4. #4
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    I have one that does it too. It's a cheapy Chinese one that just can't deal with the timing from the VIC. This is not surprising. Conventional televisions are very forgiving, newer ones are not.

  5. #5
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    I don't have the info on the various VIC chips, but I have noticed that the black vic chips have worked better for me with LCD than the gray ones (with the gold tips and gold line). For whatever reason, the gray ones have a line on the left side of the LCD that you don't see with a CRT (likely because it falls outside of the overscan area on CRT's) and sometimes have other quirks. But, as others have noted, there is a difference between LCD and CRT, however a different VIC chip could likely show improvements in your case while your current VIC chip could be perfectly fine on another system with a CRT. Unless you have multiple vic chips on hand, it could be a costly expense where it would be cheaper to try a CRT or even a different LCD that is more age appropriate.
    Retro PC's: Apple IIe, Atari 800, Atari ST, Commodore 64, Commodore Amiga 3000, TRS-80 Model 4 GA, TI-99/4A

  6. #6
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    A time base corrector should do the job, too, I would think.

  7. #7

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    Wow, I didn't expect so much answer in such a short time, and I didn't expect that serveral so interresting possible causes could erect.

    The cable is a new one from Retro Computer Shack.

    I need to get a TV that could be a good test bed. Anyway, it's curious that the problem occurs sometimes (and continues after rebooting) and not during long periods (several hours of test yesterday evening). I tend to think that a TV problem would be more systematic or would appear/disappear after a hard reboot (dur to synchro random effects for example).

    About a potentially faulty IC... I would bet on the VIC, as I don't imagine others IC creating blurred images like that. Credible ?

  8. #8
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    Quote Originally Posted by PePe-fr View Post
    About a potentially faulty IC... I would bet on the VIC, as I don't imagine others IC creating blurred images like that. Credible ?
    That would be my first assumption. With Commodore's, you really need a second (socketed) machine to have on hand... they are pretty flaky machines that have a lot of parts that are slowly dying, so swapping chips around makes things a lot easier. That said, different parts do react differently in different boards. I think that's why so many people have so many of them in their stock.
    Retro PC's: Apple IIe, Atari 800, Atari ST, Commodore 64, Commodore Amiga 3000, TRS-80 Model 4 GA, TI-99/4A

  9. #9

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    Yup.

    Hopefully, I have a second (working) C64 at home. The drawback is that the only socketed chip is the SID.
    The faulty C64 has much more socketed ICs.

  10. #10
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    Quote Originally Posted by PePe-fr View Post
    Yup.

    Hopefully, I have a second (working) C64 at home. The drawback is that the only socketed chip is the SID.
    The faulty C64 has much more socketed ICs.
    I've never seen a vic chip that wasn't socketed also.
    Retro PC's: Apple IIe, Atari 800, Atari ST, Commodore 64, Commodore Amiga 3000, TRS-80 Model 4 GA, TI-99/4A

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