Re: Apple II+ - "all" memory bad... surely not?

["N.N. Thayer" <nnthayer@hotmail.com>]

On Mar 12, 11:29 pm, "N.N. Thayer" <nntha...@hotmail.com> wrote:
> A Rev 04 II+ that I recently acquired is displaying behavior that I'd
> normally attribute to bad RAM - known good disks failing to load,
> spontaneous vomiting at the command prompt, etc.  So I loaded the
> official II+ diagnostics program (which, oddly, always loads without a
> hitch) and ran several tests.
>
> The RAM test shows a textual representation of the motherboard memory
> grid, and marks bad chips.  The test claimed that every single RAM
> chip - even those on the Language Card - was bad.  Removing the
> Language Card made no difference.  I find it hard to believe that
> *all* of it is bad... assuming that's not the case, what other sorts
> of conditions would cause such a test result?
>
> (Fortunately I have a spare Rev C motherboard from which I can
> cannibalize parts if necessary.)

CULPRITS:

74LS04
74LS138

The service notes posted by Mike Willegal were invaluable!