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Thread: Commodore 64 Black Screen Fix?

  1. #11
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    Good deal- hopefully that will revive it. PLA is by far the most common failure.

  2. #12
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    Quote Originally Posted by rittwage View Post
    Good deal- hopefully that will revive it. PLA is by far the most common failure.
    Agreed... but he'll be lucky if it's the only thing bad

    Oh, the one other thing that's had a high failure rate for me besides the PLA is the 8701 (if its a board that has that chip), you can almost just look at them the wrong way and they go bad... I keep a second working mostly socketed c64 just for testing chips now. I have one board I haven't got working yet (it's likely a logic chip since the dead test cartridge gives random results), so i have a future project to just go through and socket that entire board as well.
    -- Brian

    Retro PC's: Apple IIe/II+, Atari 800, Atari 520STFM, Commodore 64, Commodore Amiga 3000, Commodore SX-64, IBM PS/1 2121-B82, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA, Kaypro 2/84 (Not working )

  3. #13
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    That's really strange. I've repaired hundreds of them in the early 90's and probably another 50 since then and I can't recall ever having to replace that chip. Maybe I gave up on a couple and that was it... heh.

  4. #14
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    I've had a few of those go south. One ran away and fried most everything with a clock pin.

    If you had one that went bad, you probably wouldn't have missed it.

  5. #15
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    Quote Originally Posted by rittwage View Post
    That's really strange. I've repaired hundreds of them in the early 90's and probably another 50 since then and I can't recall ever having to replace that chip. Maybe I gave up on a couple and that was it... heh.
    Haha, I'm sure you're correct since you've had more experience, I might have just had bad luck. But yeah, I can see how it wouldn't be that common to replace since it's only on the later motherboards, I think the earlier motherboards had the 4 chips instead... Most of my C64's had this chip, and the two motherboards I had that didn't, one of them was utterly destroyed (they removed the ram and lifted all the traces) so it's in my parts bin and the other I couldn't get working so i just ebay'd it with a bad case and broken keyboard to keep me from spending any more time on it.
    -- Brian

    Retro PC's: Apple IIe/II+, Atari 800, Atari 520STFM, Commodore 64, Commodore Amiga 3000, Commodore SX-64, IBM PS/1 2121-B82, Tandy 1000 SX, TI-99/4A, TRS-80 Model 4 GA, Kaypro 2/84 (Not working )

  6. #16
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    Quote Originally Posted by KC9UDX View Post
    I've had a few of those go south. One ran away and fried most everything with a clock pin.

    If you had one that went bad, you probably wouldn't have missed it.
    On second thought, I'm not sure if I ever had one with that chip. The one I'm thinking of is a Motorola part.
    Be polite and I may let you live.

  7. #17

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    This board does have clock too the CPU, and it looks correct when examined with a scope. Don't think that's an issue thankfully!

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