Re: Trying to fix an Apple II+ : blue & orange colors "sparkle" & cap with only one connection

[eccofonic <eccofonic@charter.net>]

On Mon, 21 Jan 2013 19:01:40 +0100, Linards Ticmanis <ticmanis@gmx.de>
wrote:

>On 01/20/2013 08:23 PM, eccofonic wrote:
>
>Can you read circuit diagrams and twist your brain into a few knots? If
>so, try to find a copy of "Understanding the Apple II" by Jim Sather.
>It's long out of print, but there are scanned PDFs of it floating around
>on the net (just google for it). This superb book describes the whole
>Apple II/II+ circuitry in excruciating detail, but makes it as easy to
>understand as possible. You will find the blue/orange circuit as part of
>the video circuitry near the end of the book. I would think that with
>that knowledge and your description of the fault, you should be able to
>narrow down the culprit to one or a few of the 74LSxx logic chips, most
>of which are luckily still fairly easy to get. My rough guess would be
>that one of the chips at board positions A8 to A11 is faulty, but with a
>bit more thinking (which I'm currently too lazy to do) you should be
>able to narrow it down to one or two of them.
>

Yes, I see now that there's a part in the Apple II reference manual
(top of page 97) that describes A8 and A11 and part of the alternate
color circuit.

I think I've downloaded that book you describe, I'll check it out too.

Thanks for the ideas...