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  • Re: Two Commodore 64's th

    From Dennis Katsonis@1:124/5016 to Clocky on Monday, October 19, 2020 21:36:00
    Clocky wrote to Dennis Katsonis <=-

    On 4/10/2020 2:32 am, Dennis Katsonis wrote:
    Subject: Two Commodore 64's that wont power on

    I have just received FOUR breadbin Commodore 64s. One is missing the mainboard, one turns on, but with a black screen, and two don't turn on
    at all (power LED does not light up).

    Black screen is often a failed PLA. These can be replaced with modern equivalents.


    When our lockdown ends, I'm going to get a multimeter, but I'm wondering
    if there is a common and obvious cause for this that I could look at
    before I get a multimeter (which may not be for weeks because our state premier likes to imprison us).

    I've looked at the fuses, one was broken, but putting the good fuse in
    both machines didn't work.



    What supply are you using? If it's an original Commodore brick you
    should test the voltages first as they commonly fail and when they do
    they destroy the computer attached to it.

    Better still get at least a power saver or better still a modern replacement power supply.

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    I'm using an original power supply, but it works fine on one other machine. That doesn't rule it out, but it makes it less likely.

    I did switch the PLA with another machine to no effect. I suspect it could be RAM. Bad RAM I think can cause this. I do recall that one machine would start, but only have 27 bytes free. So perhaps the last remining working ram chip failed. With three boards, I should be able to get one working from parts, but it won't be easy.


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  • From Dennis Katsonis@1:124/5016 to Gary McCulloch on Tuesday, October 27, 2020 20:09:00
    Gary McCulloch wrote to Dennis Katsonis <=-

    .-: On Mon 19-Oct-2020 9:36p, Dennis Katsonis@1:124/5016.0 said to Clocky DK: chip failed. With three boards, I should be able to get one working from DK: parts, but it won't be easy.

    But it will be well worth it!

    Absolutely. I have a multimeter now, so I can perform more troubleshooting. One I think the problem is the switch, the other isn't supplying enough voltage to the chips, though the voltage regulators are outputting the correct voltage.

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