Re: My Apple ][+ is now very, very sad...

[John <john8520@gmail.com>]

Thanks for the info, that is very good to know! I do have a schematic
(its for the ][, but isn't the ][+ the same?), but no circuit
description, so I'll look for the PDF of that book. I have tried GR
and HGR modes, but not HGR2, and they show the same results. My book
'APPLE ][ Refrence Manual' has quite a bit of usefull info in it that
should be able to point me to what chips do what, where they are,
etc.

I wish I had a digital copy (or ANY copy for that matter) of the board
layout. That way I could check off what chips are what, and if
replacing/swapping did any good, as well as I could know what chip
occurs where, which makes finding them loads faster.

On Jul 14, 5:14 pm, Linards Ticmanis <ticma...@gmx.de> wrote:
> John wrote:
> > Quick thought- maybe the PSU is causing some weird interference? (The
> > fact that I can get a clear screen if I keep resetting makes me think
> > not) I can take the PSU out of my //e to test this. Also, is there any
> > chance the CPU from my //e will work in it? Its a 65C02, so I doubt
> > it. And the whats keeping the //e from working may as well be the
> > processor, so who knows.
>
> Get a schematic and a circuit description (for example from the book
> "Understanding the Apple II" which is on the net as a PDF).
>
> Identify which chips are in the video generating circuits. Luckily most
> of them are not ASICs as in the IIe and later models, but super common
> 74LSxx chips that are still readily available. Then buy a bunch of the
> right chips and swap away.
>
> With enough time and enough mental effort, a circuit description and a
> schematic might even tell you where the error is most likely to be
> located. For example, your sync generation seems to be unaffected since
> the picture is centered and stable. Have you tried the graphics modes
> (blindly type GR, HGR and HGR2)? Do they give the same appearance? If
> those work, for example, then the culprit is likely to be in the
> character generation part of the video circuit.
>
> Also, there are several 74LSxx chips that occur multiple times on the
> board. You can try swapping those around and see if you get an effect.
>
> --
> Linards Ticmanis