Re: Apple II video problem?

["Michael J. Mahon" <mjmahon@aol.com>]

MdntTrain wrote:
> On Aug 1, 6:34 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
>
> > Not laughing, but wondering whether the horizontal hold control
> > (inside the case) could have made the two cases much more similar...
>
>
> I can still try that.  Right now, I have HHold adjusted perfectly
> centered between the two points of going crazy (losing sync?).  Moving
> it one way does cause, at one point, the left shift video to suddenly
> shift more towards the center.. but it was near enough to the "going
> crazy" spot that I didn't feel secure leaving it there and opted for
> the middle.   I did not try plugging in the Rev 7 board at that spot
> to see what happened either.
>
> What are you thinking?

I'm thinking you have it correctly adjusted at the midpoint.  ;-)

Some monitors have horizontal phase lock loops that respond to
the average (middle) timing of the horizontal sync pulse, while
others (digital?) will respond more to the leading edge.  This
could make the difference in horizontal phase, since the leading-
edge-to-start-of-window timing is apparently nearly constant across
models.

-michael

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