Subj : Re: Advice on the best drive emulator?
To   : [email protected]
From : Robert Roland
Date : Fri May 13 2022 10:20 pm

On Fri, 13 May 2022 11:52:25 -0000 (UTC), phigan
<[email protected]> wrote:

>a C64 that powers on with just a
>black screen

The most useful tool for troubleshooting a black screen C64, is the
Dead Test Cartridge. Note that a black screen and a blank screen are
fundamentally different.

Throwing parts at it is a lottery. If you want to continue the
lottery, the RAM chips are a very common fault. The bad news is,
there's eight of them (or two if you have a later revision). Leave the
computer on for a minute or two and check for hot RAM chips. If they
get hot, they are definitely bad, but they can also be bad if they are
not getting hot. The Dead Test can sometimes tell you which specific
RAM chip is bad.

Another common problem is the power switch. It switches both the 5 V
DC and the 9 V AC. If the 5 V DC is not working, you will get a black
screen on the earlier revision (the longboards).

Have you checked voltages? That should come before even the Dead Test.
--
RoRo

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